Mobile Ad hoc Networking (MANET) T. Clausen
Internet-Draft LIX, Ecole Polytechnique
Intended status: Standards Track C. Dearlove
Expires: March 29, 2010 BAE Systems ATC
P. Jacquet
Project Hipercom, INRIA
The OLSRv2 Design Team
MANET Working Group
September 25, 2009
The Optimized Link State Routing Protocol version 2
draft-ietf-manet-olsrv2-10
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Abstract
This document describes version 2 of the Optimized Link State Routing
(OLSRv2) protocol for Mobile Ad hoc NETworks (MANETs).
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Applicability Statement . . . . . . . . . . . . . . . . . . . 8
4. Protocol Overview and Functioning . . . . . . . . . . . . . . 9
4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2. Routers and Interfaces . . . . . . . . . . . . . . . . . . 11
4.3. Information Base Overview . . . . . . . . . . . . . . . . 12
4.3.1. Local Information Base . . . . . . . . . . . . . . . . 12
4.3.2. Interface Information Bases . . . . . . . . . . . . . 12
4.3.3. Neighbor Information Base . . . . . . . . . . . . . . 13
4.3.4. Topology Information Base . . . . . . . . . . . . . . 13
4.3.5. Received Message Information Base . . . . . . . . . . 14
4.4. Signaling Overview . . . . . . . . . . . . . . . . . . . . 15
4.5. Routing Set . . . . . . . . . . . . . . . . . . . . . . . 16
5. Protocol Parameters and Constants . . . . . . . . . . . . . . 16
5.1. Protocol and Port Numbers . . . . . . . . . . . . . . . . 17
5.2. Multicast Address . . . . . . . . . . . . . . . . . . . . 17
5.3. Local History Times . . . . . . . . . . . . . . . . . . . 17
5.4. Message Intervals . . . . . . . . . . . . . . . . . . . . 18
5.5. Advertised Information Validity Times . . . . . . . . . . 18
5.6. Received Message Validity Times . . . . . . . . . . . . . 19
5.7. Jitter . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.8. Hop Limit Parameter . . . . . . . . . . . . . . . . . . . 20
5.9. Willingness . . . . . . . . . . . . . . . . . . . . . . . 21
5.10. Parameter Change Constraints . . . . . . . . . . . . . . . 21
6. Information Bases . . . . . . . . . . . . . . . . . . . . . . 22
6.1. Local Information Base . . . . . . . . . . . . . . . . . . 23
6.1.1. Originator Set . . . . . . . . . . . . . . . . . . . . 23
6.1.2. Local Attached Network Set . . . . . . . . . . . . . . 24
6.2. Neighbor Information Base . . . . . . . . . . . . . . . . 24
6.3. Topology Information Base . . . . . . . . . . . . . . . . 25
6.3.1. Advertising Remote Router Set . . . . . . . . . . . . 26
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6.3.2. Router Topology Set . . . . . . . . . . . . . . . . . 26
6.3.3. Routable Address Topology Set . . . . . . . . . . . . 27
6.3.4. Attached Network Set . . . . . . . . . . . . . . . . . 27
6.3.5. Routing Set . . . . . . . . . . . . . . . . . . . . . 28
6.4. Received Message Information Base . . . . . . . . . . . . 28
6.4.1. Received Set . . . . . . . . . . . . . . . . . . . . . 29
6.4.2. Processed Set . . . . . . . . . . . . . . . . . . . . 29
6.4.3. Forwarded Set . . . . . . . . . . . . . . . . . . . . 30
6.5. Corresponding Protocol Tuples . . . . . . . . . . . . . . 30
7. Message Processing and Forwarding . . . . . . . . . . . . . . 31
7.1. Actions when Receiving a Message . . . . . . . . . . . . . 32
7.2. Message Considered for Processing . . . . . . . . . . . . 32
7.3. Message Considered for Forwarding . . . . . . . . . . . . 33
8. Packets and Messages . . . . . . . . . . . . . . . . . . . . . 35
8.1. HELLO Messages . . . . . . . . . . . . . . . . . . . . . . 36
8.1.1. HELLO Message TLVs . . . . . . . . . . . . . . . . . . 37
8.1.2. HELLO Message Address Block TLVs . . . . . . . . . . . 37
8.2. TC Messages . . . . . . . . . . . . . . . . . . . . . . . 37
8.2.1. TC Message TLVs . . . . . . . . . . . . . . . . . . . 39
8.2.2. TC Message Address Block TLVs . . . . . . . . . . . . 39
9. HELLO Message Generation . . . . . . . . . . . . . . . . . . . 40
9.1. HELLO Message: Transmission . . . . . . . . . . . . . . . 41
10. HELLO Message Processing . . . . . . . . . . . . . . . . . . . 41
10.1. Updating Willingness . . . . . . . . . . . . . . . . . . . 42
10.2. Updating MPR Selectors . . . . . . . . . . . . . . . . . . 42
11. TC Message Generation . . . . . . . . . . . . . . . . . . . . 43
11.1. TC Message Transmission . . . . . . . . . . . . . . . . . 44
12. TC Message Processing . . . . . . . . . . . . . . . . . . . . 45
12.1. Invalid Message . . . . . . . . . . . . . . . . . . . . . 45
12.2. TC Message Processing Definitions . . . . . . . . . . . . 47
12.3. Initial TC Message Processing . . . . . . . . . . . . . . 47
12.3.1. Populating the Advertising Remote Router Set . . . . . 48
12.3.2. Populating the Router Topology Set . . . . . . . . . . 48
12.3.3. Populating the Routable Address Topology Set . . . . . 49
12.3.4. Populating the Attached Network Set . . . . . . . . . 49
12.4. Completing TC Message Processing . . . . . . . . . . . . . 50
12.4.1. Purging the Router Topology Set . . . . . . . . . . . 50
12.4.2. Purging the Routable Address Topology Set . . . . . . 50
12.4.3. Purging the Attached Network Set . . . . . . . . . . . 51
13. Information Base Changes . . . . . . . . . . . . . . . . . . . 51
13.1. Originator Address Changes . . . . . . . . . . . . . . . . 51
13.2. Neighbor State Changes . . . . . . . . . . . . . . . . . . 51
13.3. Advertised Neighbor Changes . . . . . . . . . . . . . . . 52
13.4. Advertising Remote Router Tuple Expires . . . . . . . . . 52
13.5. Neighborhood Changes and MPR Updates . . . . . . . . . . . 53
13.6. Routing Set Updates . . . . . . . . . . . . . . . . . . . 54
14. Selecting MPRs . . . . . . . . . . . . . . . . . . . . . . . . 54
15. Routing Set Calculation . . . . . . . . . . . . . . . . . . . 56
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15.1. Network Topology Graph . . . . . . . . . . . . . . . . . . 56
15.2. Populating the Routing Set . . . . . . . . . . . . . . . . 58
16. Proposed Values for Parameters and Constants . . . . . . . . . 59
16.1. Local History Time Parameters . . . . . . . . . . . . . . 59
16.2. Message Interval Parameters . . . . . . . . . . . . . . . 59
16.3. Advertised Information Validity Time Parameters . . . . . 59
16.4. Received Message Validity Time Parameters . . . . . . . . 60
16.5. Jitter Time Parameters . . . . . . . . . . . . . . . . . . 60
16.6. Hop Limit Parameter . . . . . . . . . . . . . . . . . . . 60
16.7. Willingness Parameter and Constants . . . . . . . . . . . 60
17. Sequence Numbers . . . . . . . . . . . . . . . . . . . . . . . 60
18. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . 61
19. Security Considerations . . . . . . . . . . . . . . . . . . . 62
19.1. Confidentiality . . . . . . . . . . . . . . . . . . . . . 62
19.2. Integrity . . . . . . . . . . . . . . . . . . . . . . . . 62
19.3. Interaction with External Routing Domains . . . . . . . . 63
20. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 64
20.1. Expert Review: Evaluation Guidelines . . . . . . . . . . . 64
20.2. Message Types . . . . . . . . . . . . . . . . . . . . . . 64
20.3. Message-Type-specific TLV Type Registries . . . . . . . . 64
20.4. Message TLV Types . . . . . . . . . . . . . . . . . . . . 65
20.5. Address Block TLV Types . . . . . . . . . . . . . . . . . 66
21. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 67
22. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 68
23. References . . . . . . . . . . . . . . . . . . . . . . . . . . 68
23.1. Normative References . . . . . . . . . . . . . . . . . . . 68
23.2. Informative References . . . . . . . . . . . . . . . . . . 69
Appendix A. Example Algorithm for Calculating MPRs . . . . . . . 69
A.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 70
A.2. MPR Selection Algorithm for each OLSRv2 Interface . . . . 71
Appendix B. Example Algorithm for Calculating the Routing Set . . 71
B.1. Local Interfaces and Neighbors . . . . . . . . . . . . . . 72
B.2. Add Neighbor Routers . . . . . . . . . . . . . . . . . . . 72
B.3. Add Remote Routers . . . . . . . . . . . . . . . . . . . . 73
B.4. Add Neighbor Addresses . . . . . . . . . . . . . . . . . . 73
B.5. Add Remote Routable Addresses . . . . . . . . . . . . . . 74
B.6. Add Attached Networks . . . . . . . . . . . . . . . . . . 74
B.7. Add 2-Hop Neighbors . . . . . . . . . . . . . . . . . . . 75
Appendix C. Example Message Layout . . . . . . . . . . . . . . . 76
Appendix D. Constraints . . . . . . . . . . . . . . . . . . . . . 77
Appendix E. Flow and Congestion Control . . . . . . . . . . . . . 81
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1. Introduction
The Optimized Link State Routing protocol version 2 (OLSRv2) is an
update to OLSRv1 as published in [RFC3626]. Compared to [RFC3626],
OLSRv2 retains the same basic mechanisms and algorithms, while using
a more flexible and efficient signaling framework, and includes some
simplification of the messages being exchanged.
OLSRv2 is developed for mobile ad hoc networks. It operates as a
table driven, proactive protocol, i.e. it exchanges topology
information with other routers in the network regularly. OLSRv2 is
an optimization of the classical link state routing protocol. Its
key concept is that of MultiPoint Relays (MPRs). Each router selects
a set of its neighbor routers (which "cover" all of its symmetrically
connected 2-hop neighbor routers) as MPRs. MPRs are then used to
achieve both flooding reduction and topology reduction.
Flooding reduction is achieved by control traffic being flooded
through the network using hop by hop forwarding, but with a router
only needing to forward control traffic which is first received
directly from one of the routers which have selected it as an MPR
(its "MPR selectors"). This mechanism, denoted "MPR flooding",
provides an efficient mechanism for information distribution within
the MANET by reducing the number of transmissions required.
Topology redction is achieved by a mechanism where the routers
selected as MPRs have a special responsibility when declaring link
state information in the network. A sufficient requirement for
OLSRv2 to provide shortest (lowest hop count) routes to all
destinations is that routers declare link state information for their
MPR selectors, if any. Routers which are not selected as MPRs need
not send any link state information. Additional available link state
information may be transmitted, e.g. for redundancy. Thus the use of
MPRs allows reduction of the number and the size of link state
messages, and in the amount of link state information maintained in
each router. Based on this reduced link state information, MPRs are
used as intermediate routers in multi-hop routes.
A router selects MPRs from among its one hop neighbors connected by
"symmetric", i.e. bidirectional, links. Therefore, selecting routes
through MPRs avoids the problems associated with data packet transfer
over unidirectional links (such as the problem of not getting link
layer acknowledgments at each hop, for link layers employing this
technique).
OLSRv2 uses and extends [NHDP] and uses [RFC5444], [RFC5497] and,
optionally, [RFC5148]. These other protocols and specifications were
all originally created as part of OLSRv2, but have been specified
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separately for wider use.
OLSRv2 makes no assumptions about the underlying link layer. OLSRv2,
through its use of [NHDP], may use link layer information and
notifications when available and applicable.
OLSRv2, as OLSRv1, inherits its concept of forwarding and relaying
from HIPERLAN (a MAC layer protocol) which is standardized by ETSI
[HIPERLAN], [HIPERLAN2].
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
All terms introduced in [RFC5444], including "packet", "message",
"Address Block", "TLV Block", and "TLV", are to be interpreted as
described there.
All terms introduced in [NHDP], including "interface", "MANET
interface", "address", "symmetric link", "symmetric 1-hop neighbor",
"symmetric 2-hop neighbor", "constant", "interface parameter", and
"router parameter", are to be interpreted as described there.
Additionally, this document uses the following terminology:
Router - A MANET router which implements the protocol specified in
this document.
OLSRv2 interface - A MANET interface running this protocol.
Routable address - An address which may be used as the destination
of a packet. A router MUST be able to distinguish a routable
address from a non-routable address by direct inpsection of the
address, based on global scope address allocations by IANA and/or
administrative configuration. Broadcast, multicast and anycast
addresses, and addresses which are limited in scope to less than
the entire MANET, MUST NOT be considered as routable addresses.
Originator address - An address which is unique (within the MANET)
to a router. A router MUST select an originator address; it MAY
choose one of its interface addresses as its originator address.
If it selects a routable address then this MUST be one which this
router will accept as destination. An originator address MUST NOT
have a prefix length.
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Message originator address - The originator address of the router
which created a message, as deduced from that message by its
recipient. The message originator address will usually be
included in the message as its <msg-orig-addr> element as defined
in [RFC5444]. However an exceptional case in a HELLO message is
also allowed by this specification when a router only uses a
single address. All messages used in this specification,
including HELLO messages defined in [NHDP], MUST have a message
originator address.
Willingness - A numerical value between WILL_NEVER and WILL_ALWAYS
(both inclusive), which represents the router's willingness to be
selected as an MPR.
Willing symmetric 1-hop neighbor - A symmetric 1-hop neighbor of
this router which has willingness not equal to WILL_NEVER.
Symmetric 1-hop neighbor through OLSRv2 interface I - A symmetric
1-hop neighbor of the router via a symmetric link using OLSRv2
interface I of the router.
Symmetric strict 2-hop neighbor - A router, X, is a symmetric strict
2-hop neighbor of a router Y, if router X is a symmetric 2-hop
neighbor of router Y and if router X is not also a willing
symmetric 1-hop neighbor of router Y.
Symmetric strict 2-hop neighbor through OLSRv2 interface I - A
symmetric strict 2-hop neighbor of the router which is a symmetric
1-hop neighbor of a willing symmetric 1-hop neighbor through
OLSRv2 interface I. The router MAY elect to consider only
information received over OLSRv2 interface I in making this
determination.
Symmetric strict 2-hop neighborhood - The symmetric strict 2-hop
neighborhood of a router X is the set of symmetric strict 2-hop
neighbors of router X.
Multipoint relay (MPR) - A router, X, is an MPR for a router, Y, if
router Y has selected router X to "re-transmit" all the broadcast
messages that it receives from router X, provided that the message
is not a duplicate, and that the hop limit field of the message is
greater than one.
MPR selector - A router, Y, is an MPR selector of router X if router
Y has selected router X as MPR.
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MPR flooding - The optimized MANET-wide information distribution
mechanism, employed by this protocol, in which a message is
relayed by only a reduced subset of the routers in the network.
MPR flooding is the mechanism by which flooding reduction is
achieved.
This document employs the same notational conventions as in [RFC5444]
and [NHDP].
3. Applicability Statement
This protocol:
o Is a proactive routing protocol for mobile ad hoc networks
(MANETs) [RFC2501].
o Is designed to work in networks with a dynamic topology, and in
which messages may be lost, such as due to collisions in wireless
networks.
o Supports routers that each have one or more participating OLSRv2
interfaces. The set of a router's interfaces may change over
time. Each OLSRv2 interface may have one or more addresses (which
may have prefix lengths), and these may also be dynamically
changing.
o Enables hop-by-hop routing, i.e., each router can use its local
information provided by this protocol to route packets.
o Continuously maintains routes to all destinations in the network,
i.e., routes are instantly available and data traffic is subject
to no delays due to route discovery. Consequently, no data
traffic buffering is required.
o Supports routers which have non-OLSRv2 interfaces which may be
local to a router or which can serve as gateways towards other
networks.
o Is optimized for large and dense networks: the larger and more
dense a network, the more optimization can be achieved by using
MPRs, compared to the classic link state algorithm.
o Uses the message format specified in [RFC5444]. This includes the
definition of a TC Message Type, used for MANET wide signaling of
network topology information.
o Allows "external" and "internal" extensibility as enabled by
[RFC5444].
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o Uses [NHDP] for discovering each router's 1-hop and symmetric
2-hop neighbors, and extends [NHDP] by addition of MPR and
willingness information.
o Is designed to work in a completely distributed manner, and does
not depend on any central entity.
4. Protocol Overview and Functioning
The objective of this protocol is for each router to, independently:
o Identify all destinations in the network.
o Identify a sufficient subset of links in the network, in order
that shortest paths can be calculated to all available
destinations.
o Provide a Routing Set, containing these shortest paths from this
router to all destinations (routable addresses and local links).
4.1. Overview
These objectives are achieved, for each router, by:
o Using [NHDP] to identify symmetric 1-hop neighbors and symmetric
2-hop neighbors.
o Independently selecting MPRs from among its symmetric 1-hop
neighbors such that all symmetric 2-hop neighbors are reachable
via at least one symmetric 1-hop neighbor. An analysis and
examples of MPR selection algorithms is given in [MPR], a
suggested algorithm is included in this specification. Note that
it is not necessary for routers to use the same algorithm in order
to interoperate in the same MANET.
o Signaling its MPR selection by extending [NHDP] to include this
information in outgoing HELLO messages, by the addition of MPR
Address Block TLV(s) associated with appropriate addresses.
o Extracting its MPR selectors from received HELLO messages, using
the included MPR Address Block TLV(s).
o Reporting its willingness to be an MPR in HELLO messages, by the
addition on an MPR_WILLING Message TLV. The router's willingness
to be an MPR indicates how willing it is to participate in MPR
flooding and to be an intermediate node for routing. A node can
absolutely decline to perform either role.
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o Periodically signaling links between MPR selectors and itself
throughout the MANET, by using TC (Topology Control) messages,
defined in this specification.
o Diffusing TC messages by using flooding reduction mechanism,
denoted "MPR flooding": only the MPRs of a router will retransmit
messages received from (i.e., originated or last relayed by) that
router.
Note that the indicated extensions to [NHDP] are of forms permitted
by that specification.
This specification defines, in turn:
o Parameters and constants used by this protocol, in addition to
those specified in [NHDP]. Parameters used by this protocol may,
where appropriate, be specific to a given OLSRv2 interface, or to
a router. This protocol allows all parameters to be changed
dynamically, and to be set independently for each router or each
OLSRv2 interface, as appropriate.
o Extensions to the Information Bases specified in [NHDP].
o Two new Information Bases: the Topology Information Base and the
Received Message Information Base.
o A requirement for each router to have an originator address to be
included in the HELLO messages of [NHDP].
o A Message TLV, to be included in the HELLO messages of [NHDP],
allowing a router to indicate its willingness to be an MPR.
o An Address Block TLV, to be included in the HELLO messages of
[NHDP], allowing a router to signal its MPR selection.
o The MPR flooding mechanism, including the inclusion of message
originator address and sequence number to manage duplicate
messages.
o TC messages, which are used for MANET wide signaling (using MPR
flooding) of selected topology (link state) information.
o The specification of new Message TLVs and Address Block TLVs which
are used in TC messages.
o The generation of TC messages from the appropriate information in
the Information Bases.
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o The updating of the Topology Information Base according to
received TC messages.
o The response to other events, such as the expiration of
information in the Information Bases.
This protocol inherits the stability of a link state algorithm and
has the advantage of having routes immediately available when needed,
due to its proactive nature.
This protocol only interacts with IP through routing table
management, and the use of the sending IP address for IP datagrams
containing OLSRv2 packets.
4.2. Routers and Interfaces
In order for a router to participate in a MANET, it MUST have at
least one, and possibly more, OLSRv2 interfaces. Each OLSRv2
interface:
o Is configured with one or more addresses, as specified in [NHDP].
These addresses MUST each be unique within the MANET and MUST
include any address that will be used as the sending address of
any IP packet sent on this OLSRv2 interface.
o Has a number of interface parameters, adding to those specified in
[NHDP].
o Has an Interface Information Base, extending that specified in
[NHDP].
o Generates and processes HELLO messages according to [NHDP],
extended as specified in Section 9 and Section 10.
In addition to a set of OLSRv2 interfaces as described above, each
router:
o May have one or more non-OLSRv2 interfaces and/or local attached
networks which this router can accept packets destined for. All
routable addresses of the router for which it is to accept packets
as destination MUST be used as an (OLSRv2 or non-OLSRv2) interface
address or of a local attached network.
o Has a number of router parameters, adding to those specified in
[NHDP].
o Has a Local Information Base, extending that specified in [NHDP],
including selection of an originator address and recording any
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locally attached networks.
o Has a Neighbor Information Base, extending that specified in
[NHDP] to record MPR selection and advertisement information.
o Has a Topology Information Base, recording information received in
TC messages and derived therefrom.
o Has a Received Message Information Base, recording information
about received messages to ensure that each TC message is only
processed once, and forwarded at most once on each OLSRv2
interface, by a router.
o Generates and processes TC messages.
4.3. Information Base Overview
Each router maintains the Information Bases described in the
following sections. These are used for describing the protocol in
this document. An implementation of this protocol MAY maintain this
information in the indicated form, or in any other organization which
offers access to this information. In particular, note that it is
not necessary to remove Tuples from Sets at the exact time indicated,
only to behave as if the Tuples were removed at that time.
4.3.1. Local Information Base
The Local Information Base is specified in [NHDP] and contains a
router's local configuration. It is extended in this specification
to also record an originator address and to include a router's:
o Originator Set, containing addresses that were recently used as
this router's originator address, and is used to enable a router
to recognize and discard control traffic which was originated by
the router itself.
o Local Attached Network Set, containing addresses of networks to
which this router can act as a gateway, and advertises in its TC
messages.
4.3.2. Interface Information Bases
The Interface Information Bases, one for each OLSRv2 interface, are
specified in [NHDP]. In addition to the uses in [NHDP], information
recorded in the Interface Information Bases is used for completing
the Routing Set.
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4.3.3. Neighbor Information Base
The Neighbor Information Base is specified in [NHDP], and is extended
to also record each neighbor's originator address, the willingness of
each neighbor to be an MPR, as well as this router's MPR
relationships with each neighbor (whether an MPR and/or an MPR
selector of that neighbor) and whether that neighbor is to be
advertised in TC messages.
A router selects some of its symmetric 1-hop neighbors as MPRs (see
Section 14). That selection is recorded in the Neighbor Set. This
selection is then reported in the router's HELLO messages, extending
the specification in [NHDP], by using an MPR Address Block TLV. In
making that selection a router MUST consider its 1-hop neighbors'
willingness to be an MPR, which (unless having default value) is
reported using an Address Block TLV in HELLO messages and recorded in
the receiving router's Neighbor Set.
A router also records in the Neighbor Set which symmetric 1-hop
neighbors have selected it as an MPR (i.e. its MPR selectors). This
is determined from the MPR TLVs in received HELLO messages. It also
records which symmetric 1-hop neighbors that it is to advertise
connectivity to in its TC messages; this MUST include all of its MPR
selectors.
The Neighbor Set finally records each 1-hop neighbor's originator
address, as included in its HELLO messages in an extension to [NHDP].
This, and other information in the Neighbor Set, including each 1-hop
neighbor's routable addresses, is used in advertising the selected
symmetric 1-hop neighbors in TC messages.
4.3.4. Topology Information Base
The purpose of the Topology Information Base is to record information
used, in addition to that in the Local Information Base, the
Interface Information Bases and the Neighbor Information Base, to
construct the Routing Set (which is also included in the Topology
Information Base).
This specification describes the calculation of the Routing Set based
on a Topology Graph constructed in two phases. First, a "backbone"
graph representing the routers in the MANET, and the connectivity
between them, is constructed from the Local Information Base, the
Neighbor Information Base and the Router Topology Set in the Topology
Information Base. Second, this graph is "decorated" with additional
destination addresses using the Local Information Base, and the
Routable Address Topology Set and the Attached Network Set in the
Topology Information Base.
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The Topology Graph does not need to be recorded in the Topology
Information Base, it can either be constructed as required when the
Routing Set is to be changed, or need not be explicitly constructed
(as illustrated in Appendix B. An implementation MAY construct and
retain the Topology Graph if preferred.
The Topology Information Base in each router contains:
o An Advertising Remote Router Set, recording each other router from
which TC messages have been received. This is used in order to
determine if a received TC messages contains fresh or outdated
information; the TC message is ignored in the latter case.
o A Router Topology Set, recording links between routers in the
MANET, as described by received TC messages.
o A Routable Address Topology Set, recording routable addresses in
the MANET (available as packet destinations) and from which other
router these addresses can be directly reached (i.e. in a single
IP hop) as reported by received TC messages.
o An Attached Network Set, recording networks to which a remote
router has advertised that it may act as a gateway. These
networks may be reached in one or more IP hops.
o A Routing Set, recording routes from this router to all available
destinations. The IP routing table is to be updated using this
Routing Set. (A router MAY choose to use any or all destination
addresses in the Routing Set to update the IP routing table, this
selection is outside the scope of this protocol.)
4.3.5. Received Message Information Base
The Received Message Information Base in each router contains:
o A Received Set for each OLSRv2 interface, describing TC messages
received by this router on that OLSRv2 interface.
o A Processed Set, describing TC messages processed by this router.
o A Forwarded Set, describing TC messages forwarded by this router.
The Received Message Information Base serves the MPR flooding
mechanism by ensuring that received messages are forwarded at most
once by a router, and also ensures that received messages are
processed exactly once by a router.
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4.4. Signaling Overview
This protocol generates and processes HELLO messages according to
[NHDP], extended according to Section 9 and Section 10 of this
specification to include an originator address and MPR selection
information.
This protocol specifies a single message type, the TC message.
This protocol is tolerant of unreliable transmissions of TC messages;
each router sends TC messages periodically, and can therefore sustain
a reasonable loss of some such messages. Such losses may occur more
frequently in wireless networks due to collisions or other
transmission problems. This protocol MAY use "jitter", randomized
adjustments to message transmission times, to reduce the incidence of
collisions as specified in [RFC5148].
This protocol is tolerant of out of sequence delivery of TC messages
due to in transit message reordering (possibly due to message
alternative routing by flooding and message loss). Each router
maintains an Advertised Neighbor Sequence Number (ANSN) which is
incremented when its recorded neighbor information that is to be
included in its TC messages changes. This ANSN is included in the
router's TC messages. The recipient of a TC message can used this
included ANSN to identify which of the information it has received is
most recent, even if messages have been re-ordered while in transit.
Only the most recent information received is used, older information
received later is discarded.
TC messages may be "complete" or "incomplete". A complete TC message
advertises all of the originating router's MPR selectors, it may also
advertise other symmetric 1-hop neighbors. Complete TC messages are
generated periodically (and also, optionally, in response to
neighborhood changes). Incomplete TC messages may be used to report
additions to advertised information without repeating unchanged
information.
TC messages, and HELLO messages as extended by this specification,
include an originator address for the router that created the
message. A TC message reports both the originator addresses and
routable addresses of its advertised neighbors, distinguishing the
two using a TLV for this purpose (an address may be both).
TC messages also report the originator's locally attached networks.
TC messages are MPR flooded throughout the MANET. A router
retransmits a TC message only if it is received from (i.e.,
originated from or was last relayed by) one of that router's MPR
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selectors.
Some TC messages may be MPR flooded over only part of the network,
e.g., allowing a router to ensure that nearer routers are kept more
up to date than distant routers, such as is used in Fisheye State
Routing [FSR] and Fuzzy Sighted Link State routing [FSLS]. This is
enabled using [RFC5497].
4.5. Routing Set
The purpose of the Routing Set is to determine and record routes
(local interface address and next hop interface address) to all
possible routable addresses and of all destinations that are local,
i.e. within one hop, to the router (whether using routable addresses
or not). Only symmetric links are used in such routes.
It is intended that the Routing Set can be used for packet routing,
by using its contents to update IP's routing tables. That update,
and whether any Routing Tuples are not used in IP's routing table, is
outside the scope of this specification.
The signaling in this specification has been designed so that a
"backbone" Topology Graph of routers, each identified by its
originator address, with at most one direct connection between any
pair of routers, can be constructed (from the Neighbor Set and the
Router Topology Set) using a suitable minimum path length algorithm,
and then this Topology Graph can have other addresses (routable, or
of symmetric 1-hop neighbors) added to it (using the Interface
Information Base, the Routable Address Topology Set and the Attached
Network Set).
5. Protocol Parameters and Constants
The parameters and constants used in this specification are those
defined in [NHDP] plus those defined in this section. The separation
in [NHDP] into interface parameters, router parameters and constants
is also used in this specification, however all but one
(RX_HOLD_TIME) of the parameters added by this protocol are router
parameters. Parameters may be categorized as follows:
o Local history times
o Message intervals
o Advertised information validity times
o Received message validity times
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o Jitter times
o Hop limits
o Willingness
In addition, constants for particular cases of a router's willingness
to be an MPR are defined. These parameters and constants are
detailed in the following sections. As for the parameters in [NHDP],
parameters defined in this document may be changed dynamically by a
router, and need not be the same on different routers, even in the
same MANET, or, for interface parameters, on different interfaces of
the same router.
5.1. Protocol and Port Numbers
This protocol specifies TC messages, which are included in packets as
defined by [RFC5444]. These packets may be sent either using the
"manet" protocol number or the "manet" well-known UDP port number, as
specified in [RFC5498].
TC messages and HELLO messages [NHDP] SHOULD, in a given deployment
of this protocol, both be using the same of either of IP or UDP, in
order that it is possible to combine messages of both protocols into
the same [RFC5444] packet for transmission.
5.2. Multicast Address
This protocol specifies TC messages, which are included in packets as
defined by [RFC5444]. These packets may be locally transmitted using
the link local multicast address "LL-MANET-Routers", as specified in
[RFC5498].
5.3. Local History Times
The following router parameter manages the time for which local
information is retained:
O_HOLD_TIME - is used to define the time for which a recently used
and replaced originator address is used to recognize the router's
own messages.
The following constraint applies to this parameter:
o O_HOLD_TIME >= 0
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5.4. Message Intervals
The following router parameters regulate TC message transmissions by
a router. TC messages are usually sent periodically, but MAY also be
sent in response to changes in the router's Neighbor Set and/or Local
Attached Network Set. With a larger value of the parameter
TC_INTERVAL, and a smaller value of the parameter TC_MIN_INTERVAL, TC
messages may more often be transmitted in response to changes in a
highly dynamic network. However because a router has no knowledge
of, for example, routers remote to it (i.e. beyond 2 hops away)
joining the network, TC messages MUST NOT be sent purely
responsively.
TC_INTERVAL - is the maximum time between the transmission of two
successive TC messages by this router. When no TC messages are
sent in response to local network changes (by design, or because
the local network is not changing) then TC messages SHOULD be sent
at a regular interval TC_INTERVAL, possibly modified by jitter as
specified in [RFC5148].
TC_MIN_INTERVAL - is the minimum interval between transmission of
two successive TC messages by this router. (This minimum interval
MAY be modified by jitter, as specified in [RFC5148].)
The following constraints apply to these parameters:
o TC_INTERVAL > 0
o TC_MIN_INTERVAL >= 0
o TC_INTERVAL >= TC_MIN_INTERVAL
o If INTERVAL_TIME TLVs as defined in [RFC5497] are included in TC
messages, then TC_INTERVAL MUST be representable as described in
[RFC5497].
5.5. Advertised Information Validity Times
The following router parameters manage the validity time of
information advertised in TC messages:
T_HOLD_TIME - is used to define the minimum Value in the
VALIDITY_TIME TLV included in all TC messages sent by this router.
If a single value of parameter TC_HOP_LIMIT (see Section 5.8) is
used then this will be the only Value in that TLV.
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A_HOLD_TIME - is the period during which TC messages are sent after
they no longer have any advertised information to report, but are
sent in order to accelerate outdated information removal by other
routers.
The following constraints apply to these parameters:
o T_HOLD_TIME > 0
o A_HOLD_TIME >= 0
o T_HOLD_TIME >= TC_INTERVAL
o If TC messages can be lost, then both T_HOLD_TIME and A_HOLD_TIME
SHOULD be significantly greater than TC_INTERVAL; a value >= 3 x
TC_INTERVAL is RECOMMENDED.
o T_HOLD_TIME MUST be representable as described in [RFC5497].
5.6. Received Message Validity Times
The following parameters manage the validity time of recorded
received message information:
RX_HOLD_TIME - is an interface parameter, and is the period after
receipt of a message by the appropriate OLSRv2 interface of this
router for which that information is recorded, in order that the
message is recognized as having been previously received on this
OLSRv2 interface.
P_HOLD_TIME - is a router parameter, and is the period after receipt
of a message which is processed by this router for which that
information is recorded, in order that the message is not
processed again if received again.
F_HOLD_TIME - is a router parameter, and is the period after receipt
of a message which is forwarded by this router for which that
information is recorded, in order that the message is not
forwarded again if received again.
The following constraints apply to these parameters:
o RX_HOLD_TIME > 0
o P_HOLD_TIME > 0
o F_HOLD_TIME > 0
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o All of these parameters SHOULD be greater than the maximum
difference in time that a message may take to traverse the MANET,
taking into account any message forwarding jitter as well as
propagation, queuing, and processing delays.
5.7. Jitter
If jitter, as defined in [RFC5148], is used then the governing jitter
parameters are as follows:
TP_MAXJITTER - represents the value of MAXJITTER used in [RFC5148]
for periodically generated TC messages sent by this router.
TT_MAXJITTER - represents the value of MAXJITTER used in [RFC5148]
for externally triggered TC messages sent by this router.
F_MAXJITTER - represents the default value of MAXJITTER used in
[RFC5148] for messages forwarded by this router. However before
using F_MAXJITTER a router MAY attempt to deduce a more
appropriate value of MAXJITTER, for example based on any
INTERVAL_TIME or VALIDITY_TIME TLVs contained in the message to be
forwarded.
For constraints on these parameters see [RFC5148].
5.8. Hop Limit Parameter
The parameter TC_HOP_LIMIT is the hop limit set in each TC message.
TC_HOP_LIMIT MAY be a single fixed value, or MAY be different in TC
messages sent by the same router. However each other router, at any
hop count distance, SHOULD see a regular pattern of TC messages, in
order that meaningful Values of INTERVAL_TIME and VALIDITY_TIME TLVs
at each hop count distance can be included as defined in [RFC5497].
Thus the pattern of TC_HOP_LIMIT SHOULD be defined to have this
property. For example the repeating pattern (255 4 4) satisfies this
property (having period TC_INTERVAL at hop counts up to 4, inclusive,
and 3 x TC_INTERVAL at hop counts greater than 4), but the repeating
pattern (255 255 4 4) does not satisfy this property because at hop
counts greater than 4, message intervals are alternately TC_INTERVAL
and 3 x TC_INTERVAL.
The following constraints apply to this parameter:
o The maximum value of TC_HOP_LIMIT >= the network diameter in hops,
a value of 255 is RECOMMENDED. Note that if using a pattern of
different values of TC_HOP_LIMIT as described above, then only the
maximum value in the patttern is so constrained.
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o All values of TC_HOP_LIMIT >= 2.
5.9. Willingness
Each router has a WILLINGNESS parameter, which MUST be in the range
WILL_NEVER to WILL_ALWAYS, inclusive, and represents the router's
willingness to be an MPR, and hence its willingness to forward
messages and be an intermediate router on routes. If a router has
WILLINGNESS = WILL_NEVER it does not perform these tasks. A MANET
using this protocol with too many routers having WILLINGNESS =
WILL_NEVER will not function; it MUST be ensured, by administrative
or other means, that this does not happen.
Routers MAY have different WILLINGNESS values; however the three
constants WILL_NEVER, WILL_DEFAULT and WILL_ALWAYS MUST have the
values defined in Section 16. (Use of WILLINGNESS = WILL_DEFAULT
allows a router to avoid including an MPR_WILLING TLV in its TC
messages, use of WILLINGNESS = WILL_ALWAYS means that a router will
always be selected as an MPR by all symmetric 1-hop neighbors.)
The following constraints apply to this parameter:
o WILLINGNESS >= WILL_NEVER
o WILLINGNESS <= WILL_ALWAYS
5.10. Parameter Change Constraints
This section presents guidelines, applicable if protocol parameters
are changed dynamically.
O_HOLD_TIME
* If O_HOLD_TIME for a router changes, then O_time for all
Originator Tuples MAY be changed.
TC_INTERVAL
* If the TC_INTERVAL for a router increases, then the next TC
message generated by this router MUST be generated according to
the previous, shorter, TC_INTERVAL. Additional subsequent TC
messages MAY be generated according to the previous, shorter,
TC_INTERVAL.
* If the TC_INTERVAL for a router decreases, then the following
TC messages from this router MUST be generated according to the
current, shorter, TC_INTERVAL.
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RX_HOLD_TIME
* If RX_HOLD_TIME for an OLSRv2 interface changes, then RX_time
for all Received Tuples for that OLSRv2 interface MAY be
changed.
P_HOLD_TIME
* If P_HOLD_TIME changes, then P_time for all Processed Tuples
MAY be changed.
F_HOLD_TIME
* If F_HOLD_TIME changes, then F_time for all Forwarded Tuples
MAY be changed.
TP_MAXJITTER
* If TP_MAXJITTER changes, then the periodic TC message schedule
on this router MAY be changed immediately.
TT_MAXJITTER
* If TT_MAXJITTER changes, then externally triggered TC messages
on this router MAY be rescheduled.
F_MAXJITTER
* If F_MAXJITTER changes, then TC messages waiting to be
forwarded with a delay based on this parameter MAY be
rescheduled.
TC_HOP_LIMIT
* If TC_HOP_LIMIT changes, and the router uses multiple values
after the change, then message intervals and validity times
included in TC messages MUST be respected. The simplest way to
do this is to start any new repeating pattern of TC_HOP_LIMIT
values with its largest value.
6. Information Bases
The purpose of this protocol is to determine the Routing Set, which
may be used to update IP's Routing Table, providing "next hop"
routing information for IP packets. This specification includes the
following Information Bases:
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Local Information Base - as defined in [NHDP], extended by the
inclusion of the router's originator address and the addition of
an Originator Set, defined in Section 6.1.1, and a Local Attached
Network Set, defined in Section 6.1.2.
Interface Information Bases - as defined in [NHDP], an Interface
Information Base for each OLSRv2 interface.
Neighbor Information Base - as defined in [NHDP], extended by the
addition of five elements to each Neighbor Tuple, and the
inclusion of an Advertised Neighbor Sequence Number (ANSN), both
as defined in Section 6.2.
Topology Information Base - this Information Base is specific to
this protocol, and is defined in Section 6.3.
Received Message Information Base - this Information Base is
specific to this protocol, and is defined in Section 6.4.
The ordering of sequence numbers, when considering which is the
greater, is as defined in Section 17.
6.1. Local Information Base
The Local Information Base as defined in [NHDP] is extended by:
o Recording the router's originator address. Note that this MAY be
equal to any address in any I_local_iface_addr_list in a Local
Interface Tuple, but MUST NOT be equal to the AL_net_addr in a
Local Attached Network Tuple.
o The addition of an Originator Set, defined in Section 6.1.1, and a
Local Attached Network Set, defined in Section 6.1.2.
All routable addresses of the router for which it is to accept
packets as destination MUST be included in the Local Interface Set or
the Local Attached Network Set.
6.1.1. Originator Set
A router's Originator Set records addresses that were recently used
as originator addresses by this router. If a router's originator
address is immutable then this set is always empty and MAY be
omitted. It consists of Originator Tuples:
(O_orig_addr, O_time)
where:
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O_orig_addr is a recently used originator address, note that this
does not include a prefix length;
O_time specifies the time at which this Tuple expires and MUST be
removed.
6.1.2. Local Attached Network Set
A router's Local Attached Network Set records its local non-OLSRv2
interfaces via which it can act as gateways to other networks. The
Local Attached Network Set is not modified by this protocol. This
protocol MAY respond to changes to the Local Attached Network Set,
which MUST reflect corresponding changes in the router's status. It
consists of Local Attached Network Tuples:
(AL_net_addr, AL_dist)
where:
AL_net_addr is the network address of an attached network which can
be reached via this router. This SHOULD be a routable address,
and MUST NOT be an interface address, or the originator address,
of this router.
AL_dist is the number of hops to the network with address
AL_net_addr from this router.
Attached networks local to this router only (i.e. not reachable
except via this router) SHOULD be treated as local non-MANET
interfaces, and added to the Local Interface Set, as specified in
[NHDP], rather than be added to the Local Attached Network Set.
Because an attached network is not specific to the router, and may be
outside the MANET, an attached network MAY also be attached to other
routers.
It is not the responsibility of this protocol to maintain routes from
this router to networks recorded in the Local Attached Network Set.
Local Attached Neighbor Tuples are removed from the Local Attached
Network Set only when the routers' local attached network
configuration changes, i.e., they are not subject to timer-based
expiration or changes due to received messages.
6.2. Neighbor Information Base
Each Neighbor Tuple in the Neighbor Set, defined in [NHDP], has these
additional elements:
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N_orig_addr is the neighbor's originator address, which may be
unknown. Note that this originator address does not include a
prefix length;
N_willingness is the neighbor's willingness to be selected as an
MPR, in the range from WILL_NEVER to WILL_ALWAYS, both inclusive;
N_mpr is a boolean flag, describing if this neighbor is selected as
an MPR by this router;
N_mpr_selector is a boolean flag, describing if this neighbor has
selected this router as an MPR, i.e., is an MPR selector of this
router.
N_advertised is a boolean flag, describing if this router has
elected to advertise a link to this neighbor in its TC messages.
A Neighbor Tuple created (but not updated) by [NHDP] MUST set:
N_orig_addr := unknown;
N_willingness := WILL_NEVER;
N_mpr := false;
N_mpr_selector := false;
N_advertised := false.
The Neighbor Information Base also includes a variable, the
Advertised Neighbor Sequence Number (ANSN), whose value is included
in TC messages to indicate the freshness of the information
transmitted. The ANSN is incremented whenever advertised information
(the originator and routable addresses included in Neighbor Tuples
with N_advertised = true, and local attached networks recorded in the
Local Attached Network Set in the Local Information Base) changes.
6.3. Topology Information Base
The Topology Information Base stores information received in TC
messages, in the Advertising Remote Router Set, the Router Topology
Set, the Routable Address Topology Set and the Attached Network Set.
Additionally, a Routing Set is maintained, derived from the
information recorded in the Local Information Base, the Interface
Information Bases, the Neighbor Information Base and the rest of the
Topology Information Base.
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6.3.1. Advertising Remote Router Set
A router's Advertising Remote Router Set records information
describing each remote router in the network that transmits TC
messages, allowing outdated TC messages to be recognized and
discarded. It consists of Advertising Remote Router Tuples:
(AR_orig_addr, AR_seq_number, AR_time)
where:
AR_orig_addr is the originator address of a received TC message,
note that this does not include a prefix length;
AR_seq_number is the greatest ANSN in any TC message received which
originated from the router with originator address AR_orig_addr
(i.e., which contributed to the information contained in this
Tuple);
AR_time is the time at which this Tuple expires and MUST be removed.
6.3.2. Router Topology Set
A router's Topology Set records topology information about the links
between routers in the MANET, allowing a "backbone" graph of all
routers to be constructed using a minimum distance algorithm. It
consists of Router Topology Tuples:
(TR_from_orig_addr, TR_to_orig_addr, TR_seq_number, TR_time)
where:
TR_from_orig_addr is the originator address of a router which can
reach the router with originator address TR_to_orig_addr in one
hop, note that this does not include a prefix length;
TR_to_orig_addr is the originator address of a router which can be
reached by the router with originator address TR_to_orig_addr in
one hop, note that this does not include a prefix length;
TR_seq_number is the greatest ANSN in any TC message received which
originated from the router with originator address
TR_from_orig_addr (i.e., which contributed to the information
contained in this Tuple);
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TR_time specifies the time at which this Tuple expires and MUST be
removed.
6.3.3. Routable Address Topology Set
A router's Routable Address Topology Set records topology information
about the routable addresses within the MANET, and via which routers
they may be reached. It consists of Routable Address Topology
Tuples:
(TA_from_orig_addr, TA_dest_addr, TA_seq_number, TA_time)
where:
TA_from_orig_addr is the originator address of a router which can
reach the router with routable address TA_dest_addr in one hop,
note that this does not include a prefix length;
TA_dest_addr is a routable address of a router which can be reached
by the router with originator address TA_from_orig_addr in one
hop;
TA_seq_number is the greatest ANSN in any TC message received which
originated from the router with originator address
TA_from_orig_addr (i.e., which contributed to the information
contained in this Tuple);
TA_time specifies the time at which this Tuple expires and MUST be
removed.
6.3.4. Attached Network Set
A router's Attached Network Set records information about networks
(which may be outside the MANET) attached to other routers and their
routable addresses. It consists of Attached Network Tuples:
(AN_orig_addr, AN_net_addr, AN_dist, AN_seq_number, AN_time)
where:
AN_orig_addr is the originator address of a router which can act as
gateway to the network with address AN_net_addr, note that this
does not include a prefix length;
AN_net_addr is the network address of an attached network, which may
be reached via the router with originator address AN_orig_addr;
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AN_dist is the number of hops to the network with address
AN_net_addr from the router with originator address AN_orig_addr;
AN_seq_number is the greatest ANSN in any TC message received which
originated from the router with originator address AN_orig_addr
(i.e., which contributed to the information contained in this
Tuple);
AN_time specifies the time at which this Tuple expires and MUST be
removed.
6.3.5. Routing Set
A router's Routing Set records the first hop along a selected path to
each destination for which any such path is known. It consists of
Routing Tuples:
(R_dest_addr, R_next_iface_addr, R_local_iface_addr, R_dist)
where:
R_dest_addr is the address of the destination, either the address of
an interface of a destination router, or the network address of an
attached network;
R_next_iface_addr is the address of the "next hop" on the selected
path to the destination;
R_local_iface_addr is the address of the local OLSRv2 interface over
which a packet MUST be sent to reach the destination by the
selected path.
R_dist is the number of hops on the selected path to the
destination;
The Routing Set for a router is derived from the contents of other
protocol Sets of the router (the Link Sets, the Neighbor Set, the
Router Topology Set, the Routable Address Topology Set, the Attached
Network Set, and OPTIONALLY the Two Hop Sets). The Routing Set is
updated (Routing Tuples added or removed, or the complete Routing Set
recalculated) when routing paths are calculated, based on changes to
these other protocol Sets. Routing Tuples are not subject to timer-
based expiration.
6.4. Received Message Information Base
The Received Message Information Base records information required to
ensure that a message is processed at most once and is forwarded at
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most once per OLSRv2 interface of a router, using MPR flooding.
6.4.1. Received Set
A router has a Received Set per OLSRv2 interface. Each Received Set
records the signatures of messages which have been received over that
OLSRv2 interface. Each consists of Received Tuples:
(RX_type, RX_orig_addr, RX_seq_number, RX_time)
where:
RX_type is the received Message Type;
RX_orig_addr is the originator address of the received message, note
that this does not include a prefix length;
RX_seq_number is the message sequence number of the received
message;
RX_time specifies the time at which this Tuple expires and MUST be
removed.
6.4.2. Processed Set
A router has a single Processed Set which records signatures of
messages which have been processed by the router. It consists of
Processed Tuples:
(P_type, P_orig_addr, P_seq_number, P_time)
where:
P_type is the processed Message Type;
P_orig_addr is the originator address of the processed message, note
that this does not include a prefix length;
P_seq_number is the message sequence number of the processed
message;
P_time specifies the time at which this Tuple expires and MUST be
removed.
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6.4.3. Forwarded Set
A router has a single Forwarded Set which records signatures of
messages which have been forwarded by the router. It consists of
Forwarded Tuples:
(F_type, F_orig_addr, F_seq_number, F_time)
where:
F_type is the forwarded Message Type;
F_orig_addr is the originator address of the forwarded message, note
that this does not include a prefix length;
F_seq_number is the message sequence number of the forwarded
message;
F_time specifies the time at which this Tuple expires and MUST be
removed.
6.5. Corresponding Protocol Tuples
In a number of cases there is a natural correspondence from a
Protocol Tuple in a Protocol Set to a single Protocol Tuple in
another Protocol Set. The latter Protocol Tuple is referred to as
"corresponding" to the former.
Specific examples include:
o There is a Local Interface Tuple corresponding to each Link Tuple,
where the Link Tuple is in the Link Set for an OLSRv2 interface,
and the Local Interface Tuple represents that OLSRv2 interface.
o There is a Neighbor Tuple corresponding to each Link Tuple which
has L_HEARD_time not expired, such that N_neighbor_addr_list
contains L_neighbor_iface_addr_list.
o There is a Link Tuple (in the Link Set in the same Interface
Information Base) corresponding to each 2-Hop Tuple such that
L_neighbor_iface_addr_list = N2_neighbor_iface_addr_list.
o There is a Neighbor Tuple corresponding to each 2-Hop Tuple, such
that N_neighbor_addr_list contains N2_neighbor_iface_addr_list.
o There is an Advertising Remote Router Tuple corresponding to each
Router Topology Tuple such that AR_orig_addr = TR_from_orig_addr.
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o There is an Advertising Remote Router Tuple corresponding to each
Routable Address Topology Tuple such that AR_orig_addr =
TA_from_orig_addr.
o There is an Advertising Remote Router Tuple corresponding to each
Attached Network Tuple such that AR_orig_addr = AN_orig_addr.
o There is an Neighbor Tuple corresponding to each Routing Tuple
such that N_neighbor_addr_list contains R_next_iface_addr.
7. Message Processing and Forwarding
This protocol defines, and hence owns, the TC message type (see
Section 20). Thus, as specified in [RFC5444], this protocol receives
all TC messages and is responsible for determining whether and how
each TC message is to be processed (updating Information Bases)
and/or forwarded, according to this specification. OLSRv2 does not
require any part of the Packet Header.
This protocol also receives HELLO messages, which are defined, and
hence owned, by [NHDP]. Such messages, when received on an OLSRv2
interface, are made available to this protocol in two ways, both as
permitted by [NHDP]. First, such received HELLO messages MUST be
made available to this protocol on reception, which allows them to be
discarded before being processed by [NHDP], for example if the
information added to the HELLO message by this protocol is
inconsistent. Second, such received HELLO messages MUST be made
available to OLSRv2 after [NHDP] has completed its processing
thereof, unless discarded as malformed by [NHDP], for processing by
this protocol. HELLO messages are not forwarded by this protocol.
Extensions to this protocol which define, and hence own, other
Messages Types, MAY manage the processing and/or forwarding of these
messages using the same mechanism as for TC messages. These
mechanisms contain elements (P_type, RX_type, F_type) required only
for such usage.
The processing selection and forwarding mechanisms are designed to
only need to parse the Message Header in order to determine whether a
message is to be processed and/or forwarded, and not to have to parse
the Message Body even if the message is forwarded (but not
processed). An implementation MAY either only parse the Message Body
if necessary, or MAY always parse the Message Body.
An implementation MUST discard the message silently if it is unable
to parse the Message Header or (if attempted) the Message Body.
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7.1. Actions when Receiving a Message
If the router receives a HELLO message from [NHDP], then the message
may be rejected before processing by [NHDP] or processed after
processing by [NHDP], both according to Section 10.
A router MUST perform the following tasks for each received TC
message (or other Message Type defined by an extension to this
protocol and specified to use this process):
1. If the router recognizes from the originator address of the
message that the message is one which the receiving router itself
originated (i.e. is the originator address of this router, or is
an O_orig_addr in an Originator Tuple) then the message MUST be
silently discarded.
2. Otherwise:
1. If the message is of a type which may be processed, including
being a TC message, then the message is considered for
processing according to Section 7.2, AND;
2. If the message is of a type which may be forwarded, including
being a TC message, AND:
+ <msg-hop-limit> is present and <msg-hop-limit> > 1, AND;
+ <msg-hop-count> is not present or <msg-hop-count> < 255
then the message is considered for forwarding according to
Section 7.3.
7.2. Message Considered for Processing
If a message (the "current message") is considered for processing,
then the following tasks MUST be performed:
1. If a Processed Tuple exists with:
* P_type = the Message Type of the current message, AND;
* P_orig_addr = the originator address of the current message,
AND;
* P_seq_number = the message sequence number of the current
message;
then the current message MUST NOT be processed.
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2. Otherwise:
1. Create a Processed Tuple with:
+ P_type := the Message Type of the current message;
+ P_orig_addr := the originator address of the current
message;
+ P_seq_number := the sequence number of the current
message;
+ P_time := current time + P_HOLD_TIME.
2. Process the current message according to its type. For a TC
message this is as defined in Section 12.
7.3. Message Considered for Forwarding
If a message (the "current message") is considered for forwarding,
then the following tasks MUST be performed:
1. If the sending address (i.e., the source address of the IP
datagram containing the current message) does not match (taking
into account any address prefix) an address in an
L_neighbor_iface_addr_list of a Link Tuple, with L_status =
SYMMETRIC, in the Link Set for the OLSRv2 interface on which the
current message was received (the "receiving interface") then the
current message MUST be silently discarded.
2. Otherwise:
1. If a Received Tuple exists in the Received Set for the
receiving interface, with:
+ RX_type = the Message Type of the current message, AND;
+ RX_orig_addr = the originator address of the current
message, AND;
+ RX_seq_number = the sequence number of the current
message;
then the current message MUST be silently discarded.
2. Otherwise:
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1. Create a Received Tuple in the Received Set for the
receiving interface with:
- RX_type := the Message Type of the current message;
- RX_orig_addr := originator address of the current
message;
- RX_seq_number := sequence number of the current
message;
- RX_time := current time + RX_HOLD_TIME.
2. If a Forwarded Tuple exists with:
- F_type = the Message Type of the current message, AND;
- F_orig_addr = the originator address of the current
message, AND;
- F_seq_number = the sequence number of the current
message.
then the current message MUST be silently discarded.
3. Otherwise if the sending address matches (taking account
of any address prefix) any address in an
L_neighbor_iface_addr_list of a Link Tuple in the Link
Set for the receiving OLSRv2 interface which has L_status
= SYMMETRIC and whose corresponding Neighbor Tuple has
N_mpr_selector = true, then:
1. Create a Forwarded Tuple with:
o F_type := the Message Type of the current message;
o F_orig_addr := originator address of the current
message;
o F_seq_number := sequence number of the current
message;
o F_time := current time + F_HOLD_TIME.
2. The Message Header of the current message is modified
by:
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o if present, decrement <msg-hop-limit> in the
Message Header by 1, AND;
o if present, increment <msg-hop-count> in the
Message Header by 1.
3. For each OLSRv2 interface of the router, include the
message in a packet to be transmitted on that OLSRv2
interface, as described in Section 8. This packet
MAY contain other forwarded messages and/or messages
generated by this router, including by other
protocols using [RFC5444]. Forwarded messages MAY be
jittered as described in [RFC5148]. The value of
MAXJITTER used in jittering a forwarded message MAY
be based on information in that message (in
particular any INTERVAL_TIME or VALIDITY_TIME TLVs in
that message) or otherwise SHOULD be with a maximum
delay of F_MAXJITTER. A router MAY modify the jitter
applied to a message in order to more efficiently
combine messages in packets, as long as the maximum
jitter is not exceeded.
8. Packets and Messages
The packet and message format used by this protocol is defined in
[RFC5444]. Except as otherwise noted, options defined in [RFC5444]
may be freely used, in particular alternative formats defined by
packet, message, Address Block and TLV flags.
This protocol may extend HELLO messages (owned by [NHDP]) by adding a
message originator address and/or TLVs to these messages when sent
over OLSRv2 interfaces, and processes these HELLO messages after
their processing by NHDP, as permitted by [NHDP].
This protocol defines and owns the TC Message Type. Extensions to
this protocol MAY define additions to TC messages. These MAY include
new Message TLVs and/or Address Block TLVs. Extensions MAY also
include new Messsage Types to be handled similarly to TC messages.
See Section 18.
Routers using this protocol exchange information through messages.
One or more messages sent by a router at the same time SHOULD be
combined into a single packet (size permitting). These messages may
have originated at the sending router, or have originated at another
router and are forwarded by the sending router. Messages with
different originating routers MAY be combined for transmission within
the same packet. Messages from other protocols defined using
[RFC5444] MAY be combined for transmission within the same packet.
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The remainder of this section defines, within the framework of
[RFC5444], Message Types and TLVs specific to this protocol. All
references in this specification to TLVs that do not indicate a type
extension, assume Type Extension = 0. TLVs in processed messages
with a type extension which is neither zero as so assumed, nor a
specifically indicated non-zero type extension, are ignored.
8.1. HELLO Messages
A HELLO message is generated as specified in [NHDP]. In addition, a
router using this protocol MUST be able to add information to such
messages, prior to these being sent on an OLSRv2 interface, as
permitted by [NHDP], so that all HELLO messages sent on an OLSRv2
interface:
o MUST allow a message originator address to be determined. This
will usually use the message's <msg-orig-addr> element as defined
in [RFC5444]. There are two permitted exceptions when the router
MAY omit a <msg-orig-addr> element, but an originator address of
the message is still correctly defined:
* If the message contains only a single local interface address,
and that address is equal to this router's originator address,
then that local interface address is the message originator
address.
* If the message contains no local interface addresses, then, as
specified in [NHDP], the source address of the IP datagram
containing the message is recognised as the only interface
address of the router. In this case, that address is also the
message originator address.
o MUST, if it is including any addresses from an
N_neighbor_addr_list that has N_mpr = true and are associated with
a TLV with Type = LINK_STATUS and Value = SYMMETRIC, include
TLV(s) with Type := MPR associated with at least one such address
from each such N_neighbor_addr_list.
o MUST NOT include any TLVs with Type = MPR associated with any
other addresses.
o MAY include a message TLV with Type := MPR_WILLING, indicating the
router's willingness to be selected as an MPR.
An router using this protocol MUST also be able to access any
incoming HELLO message received on an OLSRv2 interface, subsequent to
the processing specified in [NHDP], as permitted by [NHDP].
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8.1.1. HELLO Message TLVs
In a HELLO message, a router MUST include an MPR_WILLING Message TLV
as specified in Table 1, unless WILLINGNESS = WILL_DEFAULT (in which
case it MAY be included). A router MUST NOT include more than one
MPR_WILLING Message TLV.
+-------------+--------------+--------------------------------------+
| Type | Value Length | Value |
+-------------+--------------+--------------------------------------+
| MPR_WILLING | 1 octet | Router parameter WILLINGNESS; unused |
| | | bits (based on the maximum |
| | | willingness value WILL_ALWAYS) are |
| | | RESERVED and SHOULD be set to zero. |
+-------------+--------------+--------------------------------------+
Table 1: MPR_WILLING TLV definition
If a router does not advertise an MPR_WILLING TLV in a HELLO message,
then the router MUST be assumed to have WILLINGNESS equal to
WILL_DEFAULT.
8.1.2. HELLO Message Address Block TLVs
In a HELLO message, a router MAY include MPR Address Block TLV(s) as
specified in Table 2.
+------+--------------+-------+
| Type | Value Length | Value |
+------+--------------+-------+
| MPR | 0 octets | None. |
+------+--------------+-------+
Table 2: MPR TLV definition
8.2. TC Messages
A TC message MUST contain:
o A message originator address, using the message's <msg-orig-addr>
element as defined in [RFC5444].
o <msg-seq-num> and <msg-hop-limit> elements, as specified in
[RFC5444].
o A <msg-hop-count> element in its Message Header if the message
contains a TLV with either Type = VALIDITY_TIME or Type =
INTERVAL_TIME indicating more than one time value according to
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distance. (A TC message MAY contain <msg-hop-count> even if it
does not need to.)
o A single Message TLV with Type := CONT_SEQ_NUM, and Type Extension
:= COMPLETE or Type Extension := INCOMPLETE, as specified in
Section 8.2.1 (for complete and incomplete TC messages,
respectively) except that the latter MAY be omitted if the message
does not contain any addresses associated with a TLV with Type =
NBR_ADDR_TYPE or Type = GATEWAY.
o A Message TLV with Type := VALIDITY_TIME, as specified in
[RFC5497]. The options included in [RFC5497] for representing
zero and infinite times MUST NOT be used.
o If the TC message is complete, all addresses which are the
N_orig_addr of a Neighbor Tuple with N_advertised = true, each
associated with a TLV with Type = NBR_ADDR_TYPE, and Value =
ORIGINATOR, or with Value = ROUTABLE_ORIG if also to be associated
with Value = ROUTABLE, see Section 8.2.2. If the TC message is
incomplete then any such addresses MAY be included; if any such
addresses are included then this MUST be with the appropriate
associated TLV(s).
o If the TC message is complete, all routable addresses which are in
the N_neighbor_addr_list of a Neighbor Tuple with N_advertised =
true. Each such address MUST be associated with a TLV with Type =
NBR_ADDR_TYPE, and Value = ROUTABLE, or with Value = ROUTABLE_ORIG
if also to be associated with Value = ORIGINATOR, see
Section 8.2.2. If the TC message is incomplete then any such
addresses MAY be included; if any such addresses are included then
this MUST be with the appropriate associated TLV(s).
o If the TC message is complete, all addresses which are the
AL_net_addr of a Local Attached Network Tuple. Each such address
MUST be associated with a TLV with Type = GATEWAY, and Value =
AN_dist as specified in Section 8.2.2. If the TC message is
incomplete then any such addresses MAY be included; if included
then this MUST be with the appropriate associated TLV.
A TC message MAY contain:
o A Message TLV with Type := INTERVAL_TIME, as specified in
[RFC5497]. The options included in [RFC5497] for representing
zero and infinite times MUST NOT be used.
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8.2.1. TC Message TLVs
In each TC message which contains any addresses associated with a TLV
with Type = NBR_ADDR_TYPE or Type = GATEWAY, a router MUST include a
single CONT_SEQ_NUM Message TLV, as specified in Table 3, and with
Type Extension = COMPLETE or Type Extension = INCOMPLETE, according
to whether the TC message is complete or incomplete.
+--------------+--------------+-------------------------------------+
| Type | Value Length | Value |
+--------------+--------------+-------------------------------------+
| CONT_SEQ_NUM | 2 octets | The ANSN contained in the Neighbor |
| | | Information Base. |
+--------------+--------------+-------------------------------------+
Table 3: CONT_SEQ_NUM TLV definition
8.2.2. TC Message Address Block TLVs
In a TC message, a router MAY include NBR_ADDR_TYPE Address Block
TLV(s) as specified in Table 4.
+---------------+--------------+------------------------------------+
| Type | Value Length | Value |
+---------------+--------------+------------------------------------+
| NBR_ADDR_TYPE | 1 octet | ORIGINATOR indicates that the |
| | | address is an originator address, |
| | | ROUTABLE indicates that the |
| | | address is a routable address of |
| | | an interface, ROUTABLE_ORIG |
| | | indicates that the address is both |
+---------------+--------------+------------------------------------+
Table 4: NBR_ADDR_TYPE TLV definition
If an address is both a originator address and a routable interface
address, then it may be associated, using a TLV with Type =
NBR_ADDR_TYPE, with either a Value = ROUTABLE_ORIG, or (using two
separate TLVs) both with Value = ORIGINATOR and with Value =
ROUTABLE.
In a TC message, a router MAY include GATEWAY Address Block TLV(s) as
specified in Table 5.
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+---------+--------------+-------------------------------------+
| Type | Value Length | Value |
+---------+--------------+-------------------------------------+
| GATEWAY | 1 octet | Number of hops to attached network. |
+---------+--------------+-------------------------------------+
Table 5
All addresses included in a TC message according to this
specification MUST be associated with either at least one TLV with
Type = NBR_ADDR_TYPE or a TLV with Type = GATEWAY, but not both.
Other addresses MAY be included in the TC message, but (other than
the message originator address) are ignored by this specification.
9. HELLO Message Generation
An HELLO message is composed and generated as defined in [NHDP],
extended by the following being added to the HELLO message by this
protocol before being sent over an OLSRv2 interface, as permitted by
[NHDP]:
o A message originator address, using a <msg-orig-addr> element,
unless:
* The message contains only a single local interface address,
which is then interpreted as the message originator address,
OR;
* The message does not include any local interface addresses, as
permitted by the specification in [NHDP] when the router that
generated the HELLO message has only one interface address, and
will use that as the sending address of the IP datagram in
which the HELLO message is contained. In this case that
address MAY also be used as the message originator address.
o A Message TLV with Type := MPR_WILLING and Value := WILLINGNESS
MUST be included, unless WILLINGNESS = WILL_DEFAULT (in which case
it MAY be included).
o For each Neighbor Tuple with N_mpr = true, and for which one or
more addresses in its N_neighbor_addr_list are included with an
associated TLV with Type = LINK_STATUS and Value = SYMMETRIC, at
least one of these addresses (including a different copy of that
address, in the same or a different Address Block) MUST be
associated with an Address Block TLV with Type := MPR. Note that
other addresses (which do not meet this specification) MUST NOT be
associated with an Address Block TLV with Type = MPR, but that
more than one address from the same qualifying
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N_neighbor_addr_list MAY be associated with an Address Block TLV
with Type := MPR.
o An additional HELLO message MAY be sent when the router's set of
MPRs changes, in addition to the cases specified in [NHDP], and
subject to the same constraints.
9.1. HELLO Message: Transmission
HELLO messages are included in packets as specified in [RFC5444].
These packets may contain other messages, including TC messages.
10. HELLO Message Processing
All HELLO message processing, including determination of whether a
message is invalid, considers only TLVs with Type Extension = 0.
TLVs with any other type extension are ignored. All references to,
for example, a TLV with Type = MPR_WILLING refer to a TLV with Type =
MPR_WILLING and Type Extension = 0.
In addition to the reasons specified in [NHDP] for discarding a HELLO
message on reception, a HELLO message MUST be discarded before
processing by [NHDP] or this specification if it:
o Has more than one TLV with Type = MPR_WILLING in its Message TLV
Block.
o Has a message originator address, or any address associated with a
TLV with Type = LOCAL_IF, that the receiving router has recorded
as:
* its originator address, OR;
* as the O_orig_addr in an Originator Tuple, OR;
* in an I_local_iface_addr_list in a Local Interface Tuple, OR;
* as the IR_local_iface_addr in a Removed Interface Address
Tuple, OR;
* as the AL_net_addr in a Local Attached Network Tuple.
Note that some of these cases are already excluded by [NHDP].
o Includes any address associated with a TLV with Type = LINK_STATUS
or Type = OTHER_NEIGHB that is also the message's originator
address.
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o Contains any address associated with a TLV with Type = MPR, where
that address (including a different copy of that address, in the
same or a different Address Block) is not also associated with a
TLV with Type = LINK_STATUS and Value = SYMMETRIC.
HELLO messages are first processed as specified in [NHDP]. That
processing includes identifying (or creating) a Neighbor Tuple
corresponding to the originator of the HELLO message (the "current
Neighbor Tuple"). After this, the following MUST be performed:
1. If the HELLO message has a well-defined message originator
address, i.e., has an <msg-orig-addr> element or has zero or one
addresses associated with a TLV with Type = LOCAL_IF:
1. Remove any other Neighbor Tuples with N_orig_addr = message
originator address, taking any consequent action (including
removing one or more Link Tuples) as specified in [NHDP].
2. The current Neighbor Tuple is then updated according to:
1. N_orig_addr := message originator address;
2. Update N_willingness as described in Section 10.1;
3. Update N_mpr_selector as described in Section 10.2.
2. If there are any changes to the router's Information Bases, then
perform the processing defined in Section 13.
10.1. Updating Willingness
N_willingness in the current Neighbor Tuple is updated as follows:
1. If the HELLO message contains a Message TLV with Type =
MPR_WILLING then N_willingness := the Value of that TLV;
2. Otherwise, N_willingness := WILL_DEFAULT.
10.2. Updating MPR Selectors
N_mpr_selector is updated as follows:
1. If a router finds any of its local interface addresses (i.e.,
those contained in the I_local_iface_addr_list of an OLSRv2
interface) with an associated TLV with Type = MPR in the HELLO
message (indicating that the originating router has selected the
receiving router as an MPR) then, for the current Neighbor Tuple:
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* N_mpr_selector := true
2. Otherwise (i.e., if no such address and TLV were found) if a
router finds any of its local interface addresses with an
associated TLV with Type = LINK_STATUS and Value = SYMMETRIC in
the HELLO message, then for the current Neighbor Tuple:
* N_mpr_selector := false
* N_advertised := false
11. TC Message Generation
A router with one or more OLSRv2 interfaces, and with any Neighbor
Tuples with N_advertised = true, or with a non-empty Local Attached
Network Set MUST generate TC messages. A router which does not have
such information to advertise SHOULD also generate "empty" TC
messages for a period A_HOLD_TIME after it last generated a non-empty
TC message. TC messages (non-empty and empty) are generated
according to the following:
1. The message originator address MUST be the router's originator
address.
2. The message hop count, if included, MUST be set to zero.
3. The message hop limit MUST be set to a value greater than 1. A
router MAY use the same hop limit TC_HOP_LIMIT in all TC
messages, or use different values of the hop limit TC_HOP_LIMIT
in TC messages, see Section 5.8.
4. The message MUST contain a Message TLV with Type := CONT_SEQ_NUM
and Value := ANSN from the Neighbor Information Base. If the TC
message is complete then this Message TLV MUST have Type
Extension := COMPLETE, otherwise it MUST have Type Extension :=
INCOMPLETE. (Exception: a TC message MAY omit such a Message TLV
if the TC message is not reporting any addresses with associated
TLV with Type = NBR_ADDR_TYPE or Type = GATEWAY.)
5. The message MUST contain a Message TLV with Type :=
VALIDITY_TIME, as specified in [RFC5497]. If all TC messages are
sent with the same hop limit then this TLV MUST have Value :=
T_HOLD_TIME. If TC messages are sent with different hop limits
(more than one value of TC_HOP_LIMIT) then this TLV MUST specify
times which vary with the number of hops distance appropriate to
the chosen pattern of TC message hop limits, as specified in
[RFC5497], these times SHOULD be appropriate multiples of
T_HOLD_TIME.
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6. The message MAY contain a Message TLV with Type := INTERVAL_TIME,
as specified in [RFC5497]. If all TC messages are sent with the
same hop limit then this TLV MUST have Value := TC_INTERVAL. If
TC messages are sent with different hop limits, then this TLV
MUST specify times which vary with the number of hops distance
appropriate to the chosen pattern of TC message hop limits, as
specified in [RFC5497], these times SHOULD be appropriate
multiples of TC_INTERVAL.
7. A complete message MUST include, and an incomplete message MAY
include, in its Address Blocks:
1. N_orig_addr in each Neighbor Tuple with N_advertised = true,
associated with a TLV with Type := NBR_ADDR_TYPE and Value :=
ORIGINATOR (or Value := ROUTABLE_ORIG if also to be
associated with Value = ROUTABLE).
2. Each routable address in an N_neighbor_addr_list in each
Neighbor Tuple with N_advertised = true, associated with a
TLV with Type := NBR_ADDR_TYPE and Value := ROUTABLE (or
Value := ROUTABLE_ORIG if also to be associated with Value =
ORIGINATOR).
3. AL_net_addr in each Local Attached Neighbor Tuple, each
associated with a TLV with Type := GATEWAY and Value :=
AL_dist.
11.1. TC Message Transmission
Complete TC messages are generated and transmitted periodically on
all OLSRv2 interfaces, with a default interval between two
consecutive TC transmissions by the same router of TC_INTERVAL.
TC messages MAY be generated in response to a change in the
information which they are to advertise, indicated by a change in
ANSN. In this case a router MAY send a complete TC message, and if
so MAY re-start its TC message schedule. Alternatively a router MAY
send an incomplete TC message with at least the newly advertised
addresses (i.e. not previously, but now, an N_orig_addr or an
N_neighbor_addr_list in a Neighbor Tuple with N_advertised = true, or
in an AL_net_addr) in its Address Blocks, with associated TLV(s).
Note that a router cannot report removal of advertised content using
an incomplete TC message.
When sending a TC message in response to a change of advertised
addresses, a router must respect a minimum interval of
TC_MIN_INTERVAL between generated TC messages. Sending an incomplete
TC message MUST NOT cause the interval between complete TC messages
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to be increased, and thus a router MUST NOT send an incomplete TC
message if within TC_MIN_INTERVAL of the next scheduled complete TC
message.
The generation of TC messages, whether scheduled or triggered by a
change of contents MAY be jittered as described in [RFC5148]. The
values of MAXJITTER used SHOULD be:
o TP_MAXJITTER for periodic TC message generation;
o TT_MAXJITTER for responsive TC message generation.
TC messages are included in packets as specified in [RFC5444]. These
packets MAY contain other messages, including HELLO messages and TC
messages with different originator addresses. TC messages are
forwarded according to the specification in Section 7.3.
12. TC Message Processing
On receiving a TC message, a router MUST first check if the message
is invalid for processing by this router, as defined in Section 12.1.
Otherwise the receiving router MUST update its appropriate Interface
Information Base and its Router Information Base as specified in
Section 12.2.
All TC message processing, including determination of whether a
message is invalid, unless otherwise noted considers only TLVs with
Type Extension = 0. TLVs with any other type extension (or any
unmentioned type extension when other type extensions are considered)
are ignored. All references to, for example, a TLV with Type =
VALIDITY_TIME refer to a TLV with Type = VALIDITY_TIME and Type
Extension = 0.
Following TC message processing, if there are any changes in the
router's Information Bases, then the processing in Section 13 MUST be
performed.
12.1. Invalid Message
A received TC message is invalid for processing by this router if the
message:
o Does not include a message originator address, a message sequence
number, and a hop limit.
o Does not include a hop count, and contains a multi-value TLV with
Type = VALIDITY_TIME or Type = INTERVAL_TIME, as defined in
[RFC5497].
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o Does not have exactly one TLV with Type = VALIDITY_TIME in its
Message TLV Block.
o Has more than one TLV with Type = INTERVAL_TIME in its Message TLV
Block.
o Does not have a TLV with Type = CONT_SEQ_NUM and Type Extension =
COMPLETE or Type Extension = INCOMPLETE in its Message TLV Block,
and contains at least one address associated with a TLV with Type
= NBR_ADDR_TYPE or Type = GATEWAY.
o Has more than one TLV with Type = CONT_SEQ_NUM and Type Extension
= COMPLETE or Type Extension = INCOMPLETE in its Message TLV
Block.
o Has a message originator address, or any address associated with a
TLV with Type = NBR_ADDR_TYPE or Type = GATEWAY, that the
receiving router has recorded as:
* its originator address, OR;
* as the O_orig_addr in an Originator Tuple, OR;
* in an I_local_iface_addr_list in a Local Interface Tuple, OR;
* the IR_local_iface_addr in a Removed Interface Address Tuple.
o Has a message originator address, or any address associated with a
TLV with Type = NBR_ADDR_TYPE, that the receiving router has
recorded as the AL_net_addr in a Local Attached Network Tuple.
o Includes any address with a prefix length which is not maximal
(equal to the address length, in bits) associated with a TLV with
Type = NBR_ADDR_TYPE and Value = ORIGINATOR or Value =
ROUTABLE_ORIG.
o Includes any non-routable address associated with a TLV with Type
= NBR_ADDR_TYPE and Value = ROUTABLE or Value = ROUTABLE_ORIG.
o Includes any address associated with a TLV with Type =
NBR_ADDR_TYPE or Type = GATEWAY that is also the message's
originator address.
o Associates any address (including different copies of an address,
in the same or different Address Blocks) with more than one single
Value using one or more TLV(s) with Type = GATEWAY.
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o Associates any address (including different copies of an address,
in the same or different Address Blocks) with TLVs with Type =
NBR_ADDR_TYPE and Type = GATEWAY.
A router MAY recognize additional reasons for identifying that a
message is invalid. An invalid message MUST be silently discarded,
without updating the router's Information Bases.
12.2. TC Message Processing Definitions
When, according to Section 7.2, a TC message is to be "processed
according to its type", this means that:
o If the TC message contains a Message TLV with Type = CONT_SEQ_NUM
and Type Extension = COMPLETE, then processing according to
Section 12.3 and then according to Section 12.4 is carried out.
o If the TC message contains a Message TLV with Type = CONT_SEQ_NUM
and Type Extension = INCOMPLETE, then only processing according to
Section 12.3 is carried out.
For the purposes of this section:
o "validity time" is calculated from a VALIDITY_TIME Message TLV in
the TC message according to the specification in [RFC5497]. All
information in the TC message has the same validity time.
o "received ANSN" is defined as being the Value of a Message TLV
with Type = CONT_SEQ_NUM.
o Comparisons of sequence numbers are carried out as specified in
Section 17.
12.3. Initial TC Message Processing
The TC message is processed as follows:
1. The Advertising Remote Router Set is updated according to
Section 12.3.1. If the TC message is indicated as discarded in
that processing then the following steps are not carried out.
2. The Router Topology Set is updated according to Section 12.3.2.
3. The Routable Address Topology Set is updated according to
Section 12.3.3.
4. The Attached Network Set is updated according to Section 12.3.4.
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12.3.1. Populating the Advertising Remote Router Set
The router MUST update its Advertising Remote Router Set as follows:
1. If there is an Advertising Remote Router Tuple with:
* AR_orig_addr = message originator address; AND
* AR_seq_number > received ANSN
then the TC message MUST be discarded.
2. Otherwise:
1. If there is no Advertising Remote Router Tuple such that:
+ AR_orig_addr = message originator address;
then create an Advertising Remote Router Tuple with:
+ AR_orig_addr := message originator address.
2. This Advertising Remote Router Tuple (existing or new) is
then modified as follows:
+ AR_seq_number := received ANSN;
+ AR_time := current time + validity time.
12.3.2. Populating the Router Topology Set
The router MUST update its Router Topology Set as follows:
1. For each address (henceforth advertised address) in an Address
Block that has an associated TLV with Type = NBR_ADDR_TYPE and
Value = ORIGINATOR or Value = ROUTABLE_ORIG, perform the
following processing:
1. If there is no Router Topology Tuple such that:
+ TR_from_orig_addr = message originator address; AND
+ TR_to_orig_addr = advertised address
then create a new Router Topology Tuple with:
+ TR_from_orig_addr := message originator address
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+ TR_to_orig_addr := advertised address.
2. This Router Topology Tuple (existing or new) is then modified
as follows:
+ TR_seq_number := received ANSN;
+ TR_time := current time + validity time.
12.3.3. Populating the Routable Address Topology Set
The router MUST update its Routable Address Topology Set as follows:
1. For each address (henceforth advertised address) in an Address
Block that has an associated TLV with Type = NBR_ADDR_TYPE and
Value = ROUTABLE or Value = ROUTABLE_ORIG, perform the following
processing:
1. If there is no Routable Address Topology Tuple such that:
+ TA_from_orig_addr = message originator address; AND
+ TA_dest_addr = advertised address
then create a new Routable Address Topology Tuple with:
+ TA_from_orig_addr := message originator address;
+ TA_dest_addr := advertised address.
2. This Routable Address Topology Tuple (existing or new) is
then modified as follows:
+ TA_seq_number := received ANSN;
+ TA_time := current time + validity time.
12.3.4. Populating the Attached Network Set
The router MUST update its Attached Network Set as follows:
1. For each address (henceforth advertised address) in an Address
Block that has an associated TLV with Type = GATEWAY, and is not
an AL_net_addr in a Local Attached Network Tuple, perform the
following processing:
1. If there is no Attached Network Tuple such that:
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+ AN_net_addr = network address; AND
+ AN_orig_addr = message originator address
then create a new Attached Network Tuple with:
+ AN_net_addr := network address;
+ AN_orig_addr := message originator address.
2. This Attached Network Tuple (existing or new) is then
modified as follows:
+ AN_dist := the Value of the associated GATEWAY TLV;
+ AN_seq_number := received ANSN;
+ AN_time := current time + validity time.
12.4. Completing TC Message Processing
The TC message is processed as follows:
1. The Router Topology Set is updated according to Section 12.4.1.
2. The Routable Address Topology Set is updated according to
Section 12.4.2.
3. The Attached Network Set is updated according to Section 12.4.3.
12.4.1. Purging the Router Topology Set
The Router Topology Set MUST be updated as follows:
1. Any Router Topology Tuples with:
* TR_from_orig_addr = message originator address; AND
* TR_seq_number < received ANSN
MUST be removed.
12.4.2. Purging the Routable Address Topology Set
The Routable Address Topology Set MUST be updated as follows:
1. Any Routable Address Topology Tuples with:
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* TA_from_orig_addr = message originator address; AND
* TA_seq_number < received ANSN
MUST be removed.
12.4.3. Purging the Attached Network Set
The Attached Network Set MUST be updated as follows:
1. Any Attached Network Tuples with:
* AN_orig_addr = message originator address; AND
* AN_seq_number < received ANSN
MUST be removed.
13. Information Base Changes
The changes described in the following sections MUST be carried out
when any Information Base changes as indicated.
13.1. Originator Address Changes
If the router changes originator address, then:
1. If there is no Originator Tuple with:
* O_orig_addr = old originator address
then create an Originator Tuple with:
* O_orig_addr := old originator address
The Originator Tuple (existing or new) with:
* O_orig_addr = new originator address
is then modified as follows:
* O_time := current time + O_HOLD_TIME
13.2. Neighbor State Changes
The N_mpr_selector and N_advertised flags in Neighbor Tuples MUST be
maintained according to the following rules:
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1. If N_symmetric = false, then N_mpr_selector = false and
N_advertised = false.
2. If N_mpr_selector = true, then N_advertised = true.
3. In other cases (i.e. N_symmetric = true and N_mpr_selector =
false) a router MAY select N_advertised = true or N_advertised =
false. The more neighbors that are advertised, the larger TC
messages become, but the more redundancy is available for
routing. A router SHOULD consider the nature of its network in
making such a decision, and SHOULD avoid unnecessary changes in
advertising status, which may result both in additional TC
messages having to be sent by its neighbors, and in unnecessary
changes to routing, which will have similar effects to other
forms of topology changes in the MANET.
13.3. Advertised Neighbor Changes
The router MUST increment the ANSN in the Neighbor Information Base
whenever:
1. Any Neighbor Tuple changes its N_advertised value.
2. N_orig_addr is changed, or any routable address is added to or
removed from any Neighbor Tuple with N_advertised = true.
3. There is any change to the Local Attached Network Set.
13.4. Advertising Remote Router Tuple Expires
The Router Topology Set, the Routable Address Topology Set and the
Attached Network Set MUST be changed when an Advertising Remote
Router Tuple expires (AR_time is reached). The following changes are
required before the Advertising Remote Router Tuple is removed:
1. All Router Topology Tuples with:
* TR_from_orig_addr = AR_orig_addr of the Advertising Remote
Router Tuple
are removed.
2. All Routable Address Topology Tuples with:
* TA_from_orig_addr = AR_orig_addr of the Advertising Remote
Router Tuple
are removed.
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3. All Attached Network Tuples with:
* AN_orig_addr = AR_orig_addr of the Advertising Remote Router
Tuple
are removed.
13.5. Neighborhood Changes and MPR Updates
The set of symmetric 1-hop neighbors selected as MPRs MUST satisfy
the conditions defined in Section 14. To ensure this:
1. The set of MPRs of a router MUST be recalculated if:
* a Link Tuple is added with L_status = SYMMETRIC, OR;
* a Link Tuple with L_status = SYMMETRIC is removed, OR;
* a Link Tuple with L_status = SYMMETRIC changes to having
L_status = HEARD or L_status = LOST, OR;
* a Link Tuple with L_status = HEARD or L_status = LOST changes
to having L_status = SYMMETRIC, OR;
* a 2-Hop Tuple is added or removed, OR;
* the N_willingness of a Neighbor Tuple with N_symmetric = true
changes from WILL_NEVER to any other value, OR;
* the N_willingness of a Neighbor Tuple with N_symmetric = true
and N_mpr = true changes to WILL_NEVER from any other value,
OR;
* the N_willingness of a Neighbor Tuple with N_symmetric = true
and N_mpr = false changes to WILL_ALWAYS from any other value.
2. Otherwise, the set of MPRs of a router MAY be recalculated if the
N_willingness of a Neighbor Tuple with N_symmetric = true changes
in any other way; it SHOULD be recalculated if N_mpr = false and
this is an increase in N_willingness or if N_mpr = true and this
is a decrease in N_willingness.
If the set of MPRs of a router is recalculated, this MUST be as
described in Section 14. Before that calculation, the N_mpr of all
Neighbor Tuples are set false (although the previous values of N_mpr
MAY be used by an algorithm that minimises changes to the set of
MPRs). After that calculation the N_mpr of all Neighbor Tuples
representing symmetric 1-hop neighbors which are chosen as MPRs, are
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set true.
13.6. Routing Set Updates
The Routing Set MUST be updated, as described in Section 15 when
changes in the Local Information Base, the Neighborhood Information
Base or the Topology Information Base indicate a change of the known
symmetric links and/or attached networks in the MANET, hence changing
the Topology Graph. It is sufficient to consider only changes which
affect at least one of:
o The Local Interface Set, if the change removes any address in an
I_local_iface_addr_list. In this case, unless the OLSRv2
interface is removed, it may not be necessary to do more than
replace such addresses, if used, by an alternative address from
the same I_local_iface_addr_list.
o The Local Attached Set, if the change removes any AL_net_addr
which is also an AN_net_addr. In this case it may not be
necessary to do more than add and remove Routing Tuples with
R_dest_addr equal to that AN_net_addr.
o The Link Set of any OLSRv2 interface, and to consider only Link
Tuples which have, or just had, L_status = SYMMETRIC (including
removal of such Link Tuples).
o The Neighbor Set of the router, and to consider only Neighbor
Tuples that have, or just had, N_symmetric = true, and do not have
N_orig_addr = unknown.
o The 2-Hop Set of any OLSRv2 interface, if used in the creation of
the Routing Set.
o The Router Topology Set of the router.
o The Routable Address Topology Set of the router.
o The Attached Network Set of the router.
14. Selecting MPRs
Each router MUST select, from among its willing symmetric 1-hop
neighbors, a subset of these routers as MPRs. Only MPRs forward
control messages flooded through the MANET, thus effecting a flooding
reduction, an optimization of the classical flooding mechanism, known
as MPR flooding. MPRs MAY also be used to effect a topology
reduction in the MANET. Consequently, while it is not essential that
the set of MPRs is minimal, keeping the number of MPRs small ensures
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that the overhead is kept at a minimum.
A router MUST select MPRs for each of its OLSRv2 interfaces, but then
forms the union of those sets as its single set of MPRs. This union
MUST include all symmetric 1-hop neighbors with willingness
WILL_ALWAYS. Only this overall set of MPRs is relevant, the recorded
and used MPR relationship is one of routers, not interfaces. Routers
MAY select their MPRs by any process which satisfies the conditions
which follow. Routers can freely interoperate whether they use the
same or different MPR selection algorithms.
For each OLSRv2 interface a router MUST select a set of MPRs. This
set MUST have the properties that:
o All of the selected MPRs are willing symmetric 1-hop neighbors,
AND;
o If the selecting router sends a message on that OLSRv2 interface,
and that message is successfully forwarded by all of the selected
MPRs for that interface, then all symmetric strict 2-hop neighbors
of the selecting router through that OLSRv2 interface will receive
that message over a symmetric link.
Note that it is always possible to select a valid set of MPRs. The
set of all willing symmetric 1-hop neighbors of a router is a
(maximal) valid set of MPRs for that router. However a router SHOULD
NOT select a symmetric 1-hop neighbor with Willingness != WILL_ALWAYS
as an MPR if there are no symmetric strict 2-hop neighbors with a
symmetric link to that symmetric 1-hop neighbor. Thus a router with
no symmetric 1-hop neighbors with willingness WILL_ALWAYS and with no
symmetric strict 2-hop neighbors SHOULD NOT select any MPRs.
A router MAY select its MPRs for each OLSRv2 interface independently,
or it MAY coordinate its MPR selections across its OLSRv2 interfaces,
as long as the required condition is satisfied for each OLSRv2
interface. Each router MAY select its MPRs independently from the
MPR selection by other routers, or it MAY, for example, give
preference to routers that either are, or are not, already selected
as MPRs by other routers.
When selecting MPRs for each OLSRv2 interface independently, this MAY
be done using information from the Link Set and 2-Hop Set of that
OLSRv2 interface only, and the Neighbor Set of the router
(specifically the N_willingness elements).
The selection of MPRs (overall, not per OLSRv2 interface) is recorded
in the Neighbor Set of the router (using the N_mpr elements). A
selected MPR MUST be a willing symmetric 1-hop neighbor (i.e. the
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corresponding N_symmetric = true, and the corresponding N_willingness
!= WILL_NEVER).
A router MUST recalculate its MPRs whenever the currently selected
set of MPRs does not still satisfy the required conditions. It MAY
recalculate its MPRs if the current set of MPRs is still valid, but
could be more efficient. Sufficient conditions to recalculate a
router's set of MPRs are given in Section 13.5.
An example algorithm that creates a set of MPRs that satisfies the
required conditions is given in Appendix A.
15. Routing Set Calculation
The Routing Set of a router is populated with Routing Tuples that
represent paths from that router to all destinations in the network.
These paths are calculated based on the Network Topology Graph, which
is constructed from information in the Information Bases, obtained
via HELLO and TC message exchange.
Changes to the Routing Set do not require any messages to be
transmitted. The state of the Routing Set SHOULD, however, be
reflected in IP's routing table by adding and removing entries from
IP's routing table as appropriate. Only appropriate Routing Tuples
(in particular only those that represent local links or paths to
routable addresses) need be reflected in IP's routing table.
15.1. Network Topology Graph
The Network Topology Graph is formed from information from the
router's Local Interface Set, Link Sets, Neighbor Set, Router
Topology Set, Routable Address Topology Set and Attached Network Set.
The Network Topology Graph MAY also use information from the router's
2-Hop Sets. The Network Topology Graph forms the router's
topological view of the network in form of a directed graph. The
Network Topology Graph has a "backbone" (within which minimum
distance routes will be constructed) containing the following edges:
o Edges X -> Y for all possible Y, and one X per Y, such that:
* Y is the N_orig_addr of a Neighbor Tuple, AND;
* N_orig_addr is not unknown;
* X is in the I_local_iface_addr_list of a Local Interface Tuple,
AND;
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* There is a Link Tuple with L_status = SYMMETRIC such that this
Neighbor Tuple and this Local Interface Tuple correspond to it.
An address from L_neighbor_iface_addr_list will be denoted R in
this case.
It SHOULD be preferred, where possible, to select R = S and X from
the Local Interface Tuple corresponding to the Link Tuple from
which R was selected.
o All edges W -> U such that:
* W is the TR_from_orig_addr of a Router Topology Tuple, AND;
* U is the TR_to_orig_addr of the same Router Topology Tuple.
The Network Topology Graph is further "decorated" with the following
edges. If an address S, V, Z or T equals an address Y or W, then the
edge terminating in the address S, V, Z or T MUST NOT be used in any
path.
o Edges X -> S for all possible S, and one X per S, such that:
* S is in the N_neighbor_addr_list of a Neighbor Tuple, AND;
* X is in the I_local_iface_addr_list of a Local Interface Tuple,
AND;
* There is a Link Tuple with L_status = SYMMETRIC such that this
Neighbor Tuple and this Local Interface Tuple correspond to it.
An address from L_neighbor_iface_addr_list will be denoted R in
this case.
It SHOULD be preferred, where possible, to select R = S and X from
the Local Interface Tuple corresponding to the Link Tuple from
which R was selected.
o All edges W -> V such that:
* W is the TA_from_orig_addr of a Routable Address Topology
Tuple, AND;
* V is the TA_dest_addr of the same Routable Address Topology
Tuple.
o All edges W -> T such that:
* W is the AN_orig_addr of an Attached Network Tuple, AND;
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* T is the AN_net_addr of the same Attached Network Tuple.
o OPTIONALLY, all edges Y -> Z such that:
* Z is a routable address and is the N2_2hop_addr of a 2-Hop
Tuple, AND;
* Y is the N_orig_addr of the corresponding Neighbor Tuple, AND;
* This Neighbor Tuple has N_willingness not equal to WILL_NEVER.
A path terminating with such an edge SHOULD NOT be used in
preference to any other path.
Any part of the Topology Graph which is not connected to an address X
is not used. Only one selection X need be made from each
I_local_iface_addr_list, and only one selection R need be made from
any L_neighbor_iface_addr_list. All edges have a cost (hop count) of
one, except edges W -> T which each have a cost (hop count) equal to
the appropriate value of AN_dist.
15.2. Populating the Routing Set
The Routing Set MUST contain the shortest paths for all destinations
from all local OLSRv2 interfaces using the Network Topology Graph.
This calculation MAY use any algorithm, including any means of
choosing between paths of equal length.
Using the notation of Section 15.1, initially "backbone" paths using
only edges X -> Y and W -> U need be constructed (using a minimum
distance algorithm). Then paths using only a final edge of the other
types may be added. These MUST NOT replace backbone paths with the
same destination (and paths terminating in an edge Y -> Z SHOULD NOT
replace paths with any other form of terminating edge).
Each path will correspond to a Routing Tuple. These will be of two
types. The first type will represent single edge paths, of type X ->
S or X -> Y, by:
o R_local_iface_addr := X;
o R_next_iface_addr := R;
o R_dest_addr := S or Y;
o R_dist := 1,
where R is as defined in Section 15.1 for these types of edges.
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The second type will represent a multiple edge path, which will
always have first edge of type X -> Y, and will have final edge of
type W -> U, W -> V, W -> T or Y -> Z. The Routing Tuple will be:
o R_local_iface_addr := X;
o R_next_iface_addr := Y;
o R_dest_addr := U, V, T or Z;
o R_dist := the total hop count of the path.
Finally, Routing Tuples of the second type whose R_dest_addr is not
routable MAY be discarded.
An example algorithm for calculating the Routing Set of a router is
given in Appendix B.
16. Proposed Values for Parameters and Constants
This protocol uses all parameters and constants defined in [NHDP] and
additional parameters and constants defined in this document. All
but one (RX_HOLD_TIME) of these additional parameters are router
parameters as defined in [NHDP]. These proposed values of the
additional parameters are appropriate to the case where all
parameters (including those defined in [NHDP]) have a single value.
Proposed values for parameters defined in [NHDP] are given in that
document.
16.1. Local History Time Parameters
o O_HOLD_TIME := 30 seconds
16.2. Message Interval Parameters
o TC_INTERVAL := 5 seconds
o TC_MIN_INTERVAL := TC_INTERVAL/4
16.3. Advertised Information Validity Time Parameters
o T_HOLD_TIME := 3 x TC_INTERVAL
o A_HOLD_TIME := T_HOLD_TIME
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16.4. Received Message Validity Time Parameters
o RX_HOLD_TIME := 30 seconds
o P_HOLD_TIME := 30 seconds
o F_HOLD_TIME := 30 seconds
16.5. Jitter Time Parameters
o TP_MAXJITTER := HP_MAXJITTER
o TT_MAXJITTER := HT_MAXJITTER
o F_MAXJITTER := TT_MAXJITTER
16.6. Hop Limit Parameter
o TC_HOP_LIMIT := 255
16.7. Willingness Parameter and Constants
o WILLINGNESS := WILL_DEFAULT
o WILL_NEVER := 0
o WILL_DEFAULT := 3
o WILL_ALWAYS := 7
17. Sequence Numbers
Sequence numbers are used in this specification for the purpose of
discarding "old" information, i.e. messages received out of order.
However with a limited number of bits for representing sequence
numbers, wrap-around (that the sequence number is incremented from
the maximum possible value to zero) will occur. To prevent this from
interfering with the operation of this protocol, the following MUST
be observed when determining the ordering of sequence numbers.
The term MAXVALUE designates in the following one more than the
largest possible value for a sequence number. For a 16 bit sequence
number (as are those defined in this specification) MAXVALUE is
65536.
The sequence number S1 is said to be "greater than" the sequence
number S2 if:
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o S1 > S2 AND S1 - S2 < MAXVALUE/2 OR
o S2 > S1 AND S2 - S1 > MAXVALUE/2
When sequence numbers S1 and S2 differ by MAXVALUE/2 their ordering
cannot be determined. In this case, which should not occur, either
ordering may be assumed.
Thus when comparing two messages, it is possible - even in the
presence of wrap-around - to determine which message contains the
most recent information.
18. Extensions
An extension to this protocol will need to interact with this
specification, and possibly also with [NHDP]. This protocol is
designed to permit such interactions, in particular:
o Through accessing, and possibly extending, the information in the
Information Bases. All updates to the elements specified in this
document are subject to the constraints specified in [NHDP] and
Appendix D.
o Through accessing an outgoing message prior to it being
transmitted over any OLSRv2 interface, and to add information to
it as specified in [RFC5444]. This MAY include Message TLVs
and/or addresses with associated Address Block TLVs. (Addresses
without new associated TLVs SHOULD NOT be added to messages.)
This may, for example, be to allow a security protocol, as
suggested in Section 19, to add a TLV containing a cryptographic
signature to the message.
o Through accessing an incoming message, and potentially discarding
it prior to processing by this protocol. This may, for example,
allow a security protocol as suggested in Section 19 to perform
verification of message signatures and prevent processing and/or
forwarding of unverifiable messages by this protocol.
o Through accessing an incoming message after it has been completely
processed by this protocol. This may, in particular, allow a
protocol which has added information, by way of inclusion of
appropriate TLVs, or of addresses associated with new TLVs, access
to such information after appropriate updates have been recorded
in the Information Bases in this protocol.
o Through requesting that a message be generated at a specific time.
In that case, message generation MUST still respect the
constraints in [NHDP] and Section 5.4.
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19. Security Considerations
Currently, this protocol does not specify any special security
measures. As a proactive routing protocol, this protocol is a
potential target for various attacks. Various possible
vulnerabilities are discussed in this section.
19.1. Confidentiality
This protocol periodically MPR floods topological information to all
routers in the network. Hence, if used in an unprotected wireless
network, the network topology is revealed to anyone who listens to
the control messages.
In situations where the confidentiality of the network topology is of
importance, regular cryptographic techniques, such as exchange of
OLSRv2 control traffic messages encrypted by PGP [RFC4880] or
encrypted by some shared secret key, can be applied to ensure that
control traffic can be read and interpreted by only those authorized
to do so.
19.2. Integrity
Each router is injecting topological information into the network
through transmitting HELLO messages and, for some routers, TC
messages. If some routers for some reason, malicious or malfunction,
inject invalid control traffic, network integrity may be compromised.
Therefore, message authentication is recommended.
Different such situations may occur, for instance:
1. a router generates TC messages, advertising links to non-neighbor
routers;
2. a router generates TC messages, pretending to be another router;
3. a router generates HELLO messages, advertising non-neighbor
routers;
4. a router generates HELLO messages, pretending to be another
router;
5. a router forwards altered control messages;
6. a router does not forward control messages;
7. a router does not select multipoint relays correctly;
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8. a router forwards broadcast control messages unaltered, but does
not forward unicast data traffic;
9. a router "replays" previously recorded control traffic from
another router.
Authentication of the originator router for control messages (for
situations 2, 4 and 5) and on the individual links announced in the
control messages (for situations 1 and 3) may be used as a
countermeasure. However to prevent routers from repeating old (and
correctly authenticated) information (situation 9) temporal
information is required, allowing a router to positively identify
such delayed messages.
In general, digital signatures and other required security
information may be transmitted as a separate Message Type, or
signatures and security information may be transmitted within the
HELLO and TC messages, using the TLV mechanism. Either option
permits that "secured" and "unsecured" routers can coexist in the
same network, if desired,
Specifically, the authenticity of entire control packets can be
established through employing IPsec authentication headers, whereas
authenticity of individual links (situations 1 and 3) require
additional security information to be distributed.
An important consideration is that all control messages are
transmitted either to all routers in the neighborhood (HELLO
messages) or broadcast to all routers in the network (TC messages).
For example, a control message in this protocol is always a point-to-
multipoint transmission. It is therefore important that the
authentication mechanism employed permits that any receiving router
can validate the authenticity of a message. As an analogy, given a
block of text, signed by a PGP private key, then anyone with the
corresponding public key can verify the authenticity of the text.
19.3. Interaction with External Routing Domains
This protocol does, through the use of TC messages, provide a basic
mechanism for injecting external routing information to this
protocol's domain. Routing information can be extracted from the
protocol's Information Bases, in particular the Routing Set, of this
protocol and, potentially, injected into an external domain, if the
routing protocol governing that domain permits this.
When operating routers connecting a MANET using this protocol to an
external routing domain, care MUST be taken not to allow potentially
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insecure and untrustworthy information to be injected from this
domain to external routing domains. Care MUST also be taken to
validate the correctness of information prior to it being injected as
to avoid polluting routing tables with invalid information.
A recommended way of extending connectivity from an existing routing
domain to a MANET routed using this protocol is to assign an IP
prefix (under the authority of the routers/gateways connecting the
MANET with the exiting routing domain) exclusively to that MANET
area, and to statically configure the gateways to advertise routes
for that IP sequence to routers in the existing routing domain.
20. IANA Considerations
This specification defines one Message Type, which must be allocated
from the "Message Types" repository of [RFC5444], two Message TLV
Types, which must be allocated from the "Message TLV Types"
repository of [RFC5444], and three Address Block TLV Types, which
must be allocated from the "Address Block TLV Types" repository of
[RFC5444].
20.1. Expert Review: Evaluation Guidelines
For the registries where an Expert Review is required, the designated
expert SHOULD take the same general recommendations into
consideration as are specified by [RFC5444].
20.2. Message Types
This specification defines one Message Type, to be allocated from the
0-223 range of the "Message Types" namespace defined in [RFC5444], as
specified in Table 6.
+------+------+-----------------------------------------+
| Name | Type | Description |
+------+------+-----------------------------------------+
| TC | TBD1 | Topology Control (MANET-wide signaling) |
+------+------+-----------------------------------------+
Table 6: Message Type assignment
20.3. Message-Type-specific TLV Type Registries
IANA is requested to create a registry for Message-Type-specific
Message TLVs for TC messages, in accordance with Section 6.2.1 of
[RFC5444], and with initial assignments and allocation policies as
specified in Table 7.
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+---------+-------------+-------------------+
| Type | Description | Allocation Policy |
+---------+-------------+-------------------+
| 128-223 | Unassigned | Expert Review |
+---------+-------------+-------------------+
Table 7: TC Message-Type-specific Message TLV Types
IANA is requested to create a registry for Message-Type-specific
Address Block TLVs for TC messages, in accordance with Section 6.2.1
of [RFC5444], and with initial assignments and allocation policies as
specified in Table 8.
+---------+-------------+-------------------+
| Type | Description | Allocation Policy |
+---------+-------------+-------------------+
| 128-223 | Unassigned | Expert Review |
+---------+-------------+-------------------+
Table 8: TC Message-Type-specific Address Block TLV Types
20.4. Message TLV Types
This specification defines two Message TLV Types, which must be
allocated from the "Message TLV Types" namespace defined in
[RFC5444]. IANA are requested to make allocations in the 8-127 range
for these types. This will create two new Type Extension registries
with assignments as specified in Table 9 and Table 10.
Specifications of these TLVs are in Section 8.1.1 and Section 8.2.1,
respectively. Each of these TLVs MUST NOT be included more than once
in a Message TLV Block.
+-------------+------+-----------+----------------------------------+
| Name | Type | Type | Description |
| | | Extension | |
+-------------+------+-----------+----------------------------------+
| MPR_WILLING | TBD2 | 0 | Specifies the originating |
| | | | router's willingness to act as a |
| | | | relay and to partake in network |
| | | | formation |
| Unassigned | TBD2 | 1-255 | Expert Review |
+-------------+------+-----------+----------------------------------+
Table 9: Message TLV Type assignment: MPR_WILLING
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+--------------+------+----------------+----------------------------+
| Name | Type | Type Extension | Description |
+--------------+------+----------------+----------------------------+
| CONT_SEQ_NUM | TBD3 | 0 (COMPLETE) | Specifies a content |
| | | | sequence number for this |
| | | | complete message |
| CONT_SEQ_NUM | TBD3 | 1 (INCOMPLETE) | Specifies a content |
| | | | sequence number for this |
| | | | incomplete message |
| Unassigned | TBD3 | 2-255 | Expert Review |
+--------------+------+----------------+----------------------------+
Table 10: Message TLV Type assignment: CONT_SEQ_NUM
Type extensions indicated as Expert Review SHOULD be allocated as
described in [RFC5444], based on Expert Review as defined in
[RFC5226].
20.5. Address Block TLV Types
This specification defines three Address Block TLV Types, which must
be allocated from the "Address Block TLV Types" namespace defined in
[RFC5444]. IANA are requested to make allocations in the 8-127 range
for these types. This will create three new Type Extension
registries with assignments as specified in Table 11, Table 12 and
Table 13, respectively. Specifications of these TLVs are in
Section 8.1.2 and Section 8.2.2.
+------------+------+-----------+-----------------------------------+
| Name | Type | Type | Description |
| | | Extension | |
+------------+------+-----------+-----------------------------------+
| MPR | TBD4 | 0 | Specifies that a given address is |
| | | | of a router selected as an MPR |
| Unassigned | TBD4 | 1-255 | Expert Review |
+------------+------+-----------+-----------------------------------+
Table 11: Address Block TLV Type assignment: MPR
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+---------------+------+-----------+--------------------------------+
| Name | Type | Type | Description |
| | | Extension | |
+---------------+------+-----------+--------------------------------+
| NBR_ADDR_TYPE | TBD5 | 0 | Specifies that a given address |
| | | | is of a neighbor reached via |
| | | | the originating router |
| Unassigned | TBD5 | 1-255 | Expert Review |
+---------------+------+-----------+--------------------------------+
Table 12: Address Block TLV Type assignment: NBR_ADDR_TYPE
The Values which the NBR_ADDR_TYPE Address Block TLV can use are the
following:
o ORIGINATOR := 1;
o ROUTABLE := 2;
o ROUTABLE_ORIG := 3.
+------------+------+-----------+-----------------------------------+
| Name | Type | Type | Description |
| | | extension | |
+------------+------+-----------+-----------------------------------+
| GATEWAY | TBD6 | 0 | Specifies that a given address is |
| | | | reached via a gateway on the |
| | | | originating router |
| Unassigned | TBD6 | 1-255 | Expert Review |
+------------+------+-----------+-----------------------------------+
Table 13: Address Block TLV Type assignment: GATEWAY
Type extensions indicated as Expert Review SHOULD be allocated as
described in [RFC5444], based on Expert Review as defined in
[RFC5226].
21. Contributors
This specification is the result of the joint efforts of the
following contributors -- listed alphabetically.
o Cedric Adjih, INRIA, France, <Cedric.Adjih@inria.fr>
o Emmanuel Baccelli, INRIA , France, <Emmanuel.Baccelli@inria.fr>
o Thomas Heide Clausen, LIX, France, <T.Clausen@computer.org>
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o Justin Dean, NRL, USA, <jdean@itd.nrl.navy.mil>
o Christopher Dearlove, BAE Systems, UK,
<chris.dearlove@baesystems.com>
o Satoh Hiroki, Hitachi SDL, Japan, <hiroki.satoh.yj@hitachi.com>
o Philippe Jacquet, INRIA, France, <Philippe.Jacquet@inria.fr>
o Monden Kazuya, Hitachi SDL, Japan, <kazuya.monden.vw@hitachi.com>
o Kenichi Mase, Niigata University, Japan, <mase@ie.niigata-u.ac.jp>
o Ryuji Wakikawa, Toyota, Japan, <ryuji@sfc.wide.ad.jp>
22. Acknowledgments
The authors would like to acknowledge the team behind OLSRv1,
specified in RFC3626, including Anis Laouiti (INT, Paris), Pascale
Minet (INRIA, France), Laurent Viennot (INRIA, France), and Amir
Qayyum (M.A. Jinnah University, Islamabad) for their contributions.
The authors would like to gratefully acknowledge the following people
for intense technical discussions, early reviews and comments on the
specification and its components (listed alphabetically): Khaldoun Al
Agha (LRI), Teco Boot (Infinity Networks), Song-Yean Cho (LIX), Alan
Cullen (BAE Systems), Louise Lamont (CRC), Li Li (CRC), Joe Macker
(NRL), Richard Ogier (SRI), Charles E. Perkins (WiChorus), Henning
Rogge (FGAN), and the entire IETF MANET working group.
23. References
23.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, BCP 14, March 1997.
[RFC5148] Clausen, T., Dearlove, C., and B. Adamson, "Jitter
considerations in MANETs", RFC 5148, February 2008.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226, BCP 26,
May 2008.
[RFC5444] Clausen, T., Dean, J., Dearlove, C., and C. Adjih,
"Generalized MANET Packet/Message Format", RFC 5444,
February 2009.
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[RFC5497] Clausen, T. and C. Dearlove, "Representing multi-value
time in MANETs", RFC 5497, March 2009.
[RFC5498] Chakeres, I., "IANA Allocations for MANET Protocols",
RFC 5498, March 2009.
[NHDP] Clausen, T., Dean, J., and C. Dearlove, "MANET
Neighborhood Discovery Protocol (NHDP)", work in
progress draft-ietf-manet-nhdp-10.txt, July 2009.
23.2. Informative References
[RFC2501] Macker, J. and S. Corson, "Mobile Ad hoc Networking
(MANET): Routing Protocol Performance Issues and
Evaluation Considerations", RFC 2501, January 1999.
[RFC3626] Clausen, T. and P. Jacquet, "The Optimized Link State
Routing Protocol", RFC 3626, October 2003.
[RFC4880] Callas, J., Donnerhacke, L., Finney, H., and R. Thayer,
"OpenPGP message format", RFC 4880, November 2007.
[HIPERLAN] ETSI, "ETSI STC-RES10 Committee. Radio equipment and
systems: HIPERLAN type 1, functional specifications ETS
300-652", June 1996.
[HIPERLAN2] Jacquet, P., Minet, P., Muhlethaler, P., and N.
Rivierre, "Increasing reliability in cable free radio
LANs: Low level forwarding in HIPERLAN.", 1996.
[MPR] Qayyum, A., Viennot, L., and A. Laouiti, "Multipoint
relaying: An efficient technique for flooding in mobile
wireless networks.", 2001.
[FSR] Pei, G., Gerla, M., and T. Chen, "Fisheye state routing
in mobile ad hoc networks", 2000.
[FSLS] Santivanez, C., Ramanathan, R., and I. Stavrakakis,
"Making link-state routing scale for ad hoc networks",
2000.
Appendix A. Example Algorithm for Calculating MPRs
The following specifies an algorithm which MAY be used to select
MPRs. MPRs are calculated per OLSRv2 interface, but then a single
set of MPRs is formed from the union of the MPRs for all OLSRv2
interfaces. (As noted in Section 14 a router MAY improve on this, by
coordination between OLSRv2 interfaces.) A router's MPRs are
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recorded using the element N_mpr in Neighbor Tuples.
If using this example algorithm then the following steps MUST be
executed in order for a router to select its MPRs:
1. Set N_mpr := false in all Neighbor Tuples;
2. For each Neighbor Tuple with N_symmetric = true and N_willingness
= WILL_ALWAYS, set N_mpr := true;
3. For each OLSRv2 interface of the router, use the algorithm in
Appendix A.2. Note that this sets N_mpr := true for some
Neighbor Tuples, these routers are already selected as MPRs when
using the algorithm for following OLSRv2 interfaces.
4. OPTIONALLY, consider each selected MPR in turn, and if the set of
selected MPRs without that router still satisfies the necessary
conditions, for all OLSRv2 interfaces, then that router MAY be
removed from the set of MPRs. This process MAY be repeated until
no MPRs are removed. Routers MAY be considered in order of
increasing N_willingness.
Note that only symmetric strict 2-hop neighbors are considered, thus:
o Symmetric 1-hop neighbor routers with N_willingness = WILL_NEVER
MUST NOT be selected as MPRs, and MUST be ignored in the following
algorithm (and hence also ignore any 2-Hop Tuples whose
N2_neighbor_iface_addr_list is included in the
N_neighbor_addr_list of any such Neighbor Tuple).
o Symmetric 2-hop neighbor routers which are also symmetric 1-hop
neighbor routers MUST be ignored in the following algorithm (i.e.
ignore any 2-Hop Tuples whose N2_2hop_addr is in the
N_neighbor_addr_list of any Neighbor Tuple).
A.1. Terminology
The following terminology will be used when selecting MPRs for the
OLSRv2 interface I:
N(I) - The set of symmetric 1-hop neighbors which have a symmetric
link to I.
N2(I) - The set of addresses of interfaces of a router with a
symmetric link to a router in N(I); this MAY be restricted to
considering only information received over I (in which case N2(I)
is the set of N2_2hop_addr in 2-Hop Tuples in the 2-Hop Set for
OLSRv2 interface I).
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Connected to I via Y - An address A in N2(I) is connected to I via a
router Y in N(I) if A is an address of an interface of a symmetric
1-hop neighbor of Y (i.e. A is the N2_2hop_addr in a 2-Hop Tuple
in the 2-Hop Set for OLSRv2 interface I, and whose
N2_neighbor_iface_addr_list is contained in the set of interface
addresses of Y).
D(Y, I) - For a router Y in N(I), the number of addresses in N2(I)
which are connected to I via Y.
R(Y, I): - For a router Y in N(I), the number of addresses in N2(I)
which are connected to I via Y, but are not connected to I via any
router which has already been selected as an MPR.
A.2. MPR Selection Algorithm for each OLSRv2 Interface
When selecting MPRs for the OLSRv2 interface I:
1. For each address A in N2(I) for which there is only one router Y
in N(I) such that A is connected to I via Y, select that router Y
as an MPR (i.e. set N_mpr := true in the Neighbor Tuple
corresponding to Y).
2. While there exists any router Y in N(I) with R(Y, I) > 0:
1. Select a router Y in N(I) with R(Y, I) > 0 in the following
order of priority:
+ greatest N_willingness in the Neighbor Tuple corresponding
to Y, THEN;
+ greatest R(Y, I), THEN;
+ greatest D(Y, I), THEN;
+ N_mpr_selector is equal to true, if possible, THEN;
+ any choice.
2. Select Y as an MPR (i.e. set N_mpr := true in the Neighbor
Tuple corresponding to Y).
Appendix B. Example Algorithm for Calculating the Routing Set
The following procedure is given as an example for calculating the
Routing Set using a variation of Dijkstra's algorithm. First all
Routing Tuples are removed, and then, using the selections and
definitions in Appendix B.1, the procedures in the following sections
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(each considered a "stage" of the processing) are applied in turn.
B.1. Local Interfaces and Neighbors
The following selections and definitions are made:
1. For each Local Interface Tuple, select an address from its
I_local_iface_addr_list, this is defined as the selected address
for this Local Interface Tuple.
2. For each Link Tuple, the selected address of its corresponding
Local Interface Tuple is defined as the selected local address
for this Local Interface Tuple.
3. For each Neighbor Tuple with N_symmetric = true, the selected
local address is defined as the selected local address of the
selected Link Tuple for that Neighbor Tuple.
4. For each address (N_orig_addr or in N_neighbor_addr_list, the
"neighbor address") from a Neighbor Tuple with N_symmetric =
true, select a Link Tuple with L_status = SYMMETRIC whose
corresponding Neighbor Tuple is this Neighbor Tuple and where, if
possible, L_neighbor_iface_addr_list contains the neighbor
address. This is defined as the selected Link Tuple for that
neighbor address.
5. For each address (N_orig_addr or in N_neighbor_addr_list, the
"neighbor address") from a Neighbor Tuple with N_symmetric =
true, a selected address from the L_neighbor_iface_addr_list of
the selected Link Tuple for the neighbor address, if possible
equal to the neighbor address, is defined as the selected link
address for that neighbor address.
6. Routing Tuple preference is decided by preference for
corresponding Neighbor Tuples in this order:
* For greater N_willingness.
* For N_mpr_selector = true over N_mpr_selector = false.
B.2. Add Neighbor Routers
The following procedure is executed once.
1. For each Neighbor Tuple with N_symmetric = true, add a Routing
Tuple with:
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* R_dest_addr := N_orig_addr;
* R_next_iface_addr := selected link address;
* R_local_iface_addr := selected local address;
* R_dist := 1.
B.3. Add Remote Routers
The following procedure is executed for each value of h, starting
with h := 1 and incrementing by 1 for each iteration. The execution
MUST stop if no new Routing Tuples are added in an iteration.
1. For each Router Topology Tuple, if:
* TR_to_orig_addr is not equal to the R_dest_addr of any Routing
Tuple added in an earlier stage, AND;
* TR_from_orig_addr is equal to the R_dest_addr of a Routing
Tuple with R_dist = h (the "previous Routing Tuple"),
then add a new Routing Tuple, with:
* R_dest_addr := TR_to_orig_addr;
* R_next_iface_addr := R_next_iface_addr of the previous Routing
Tuple;
* R_local_iface_addr := R_local_iface_addr of the previous
Routing Tuple;
* R_dist := h+1.
There may be more than one possible Routing Tuple that may be
added for an R_dest_addr in this stage. If so, then, for each
such R_dest_addr, a Routing Tuple which is preferred SHOULD be
added.
B.4. Add Neighbor Addresses
The following procedure is executed once.
1. For each Neighbor Tuple with N_symmetric = true:
1. For each address (the "current address") in
N_neighbor_addr_list, if the current address is not equal to
the R_dest_addr of any Routing Tuple, then add a new Routing
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Tuple, with:
+ R_dest_addr := current address;
+ R_next_iface_addr := selected link address;
+ R_local_iface_addr := selected local address;
+ R_dist := 1.
B.5. Add Remote Routable Addresses
The following procedure is executed once.
1. For each Routable Address Topology Tuple, if:
* TA_dest_addr is not equal to the R_dest_addr of any Routing
Tuple added in an earlier stage, AND;
* TR_from_orig_addr is equal to the R_dest_addr of a Routing
Tuple (the "previous Routing Tuple"),
then add a new Routing Tuple, with:
* R_dest_addr := TA_dest_addr;
* R_next_iface_addr := R_next_iface_addr of the previous Routing
Tuple;
* R_local_iface_addr := R_local_iface_addr of the previous
Routing Tuple;
* R_dist := R_dist of the previous Routing Tuple + 1.
There may be more than one possible Routing Tuple that may be
added for an R_dest_addr in this stage. If so, then, for each
such R_dest_addr, a Routing Tuple which is preferred SHOULD be
added.
B.6. Add Attached Networks
The following procedure is executed once.
1. For each Attached Network Tuple, if:
* AN_orig_addr is not equal to the R_dest_addr of any Routing
Tuple added in an earlier stage, AND;
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* AN_orig_addr is equal to the R_dest_addr of a Routing Tuple
(the "previous Routing Tuple),
then add a new Routing Tuple, with:
* R_dest_addr := AN_net_addr;
* R_next_iface_addr := R_next_iface_addr of the previous Routing
Tuple;
* R_local_iface_addr := R_local_iface_addr of the previous
Routing Tuple;
* R_dist := R_dist of the previous Routing Tuple + AN_dist.
There may be more than one possible Routing Tuple that may be
added for an R_dest_addr in this stage. If so, then, for each
such R_dest_addr, a Routing Tuple with minimum R_dist MUST be
selected, otherwise a Routing Tuple which is preferred SHOULD be
added.
B.7. Add 2-Hop Neighbors
The following procedure is executed once.
1. For each 2-Hop Tuple, if:
* N2_2hop_addr is a routable address, AND;
* N2_2hop_addr is not equal to the R_dest_addr of any Routing
Tuple added in an earlier stage,
then define the "previous Routing Tuple" as that with R_dest_addr
= N_orig_addr of the corresponding Neighbor Tuple, and add a new
Routing Tuple, with:
* R_dest_addr := N2_2hop_addr;
* R_next_iface_addr := R_next_iface_addr of the previous Routing
Tuple;
* R_local_iface_addr := R_local_iface_addr of the previous
Routing Tuple;
* R_dist := 2.
There may be more than one possible Routing Tuple that may be
added for an R_dest_addr in this stage. If so, then, for each
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such R_dest_addr, a Routing Tuple which is preferred SHOULD be
added.
Appendix C. Example Message Layout
An example TC message is as follows. The message has full Message
Header (four bit Flags field value is 15). Its four bit Message
Address Length field has value 3 and hence addresses in the message
have length four octets, here being IPv4 addresses. The overall
message length is 57 octets.
The message has a Message TLV Block with content length 13 octets
containing three TLVs. The first two TLVs are interval and validity
times for the message. The third TLV is the content sequence number
TLV used to carry the 2 octet ANSN, and (with default type extension
zero, i.e. COMPLETE) indicating that the TC message is complete.
Each TLV uses a TLV with Flags octet value 16, indicating that it has
a Value, but no type extension or start and stop indexes. The first
two TLVs have a Value Length of 1 octet, the last has a Value Length
of 2 octets.
The message has two Address Blocks. (This is not necessary, the
information could be conveyed using a single Address Block, the use
of two Address Blocks, which is also allowed, is illustrative only.)
The first Address Block contains 3 addresses, with Flags octet value
128, hence with a Head section, (with length 2 octets) but no Tail
section, and hence Mid sections with length two octets. The
following TLV Block (content length 6 octets) contains a single
NBR_ADDR_TYPE TLV (Flags octet value 16, includes a Value but no
indexes) indicating that these addresses are associated with the
Value (with Value Length 1 octet) ROUTABLE_ORIG, i.e. they are
originator addresses of advertised neighbors that are also routable
addresses.
The second Address Block contains 1 address, with Flags octet 176
indicating that there is a Head section (with length 2 octets), that
the Tail section (length 2 octets) consists of zero valued octets
(not included), and that there is a single prefix length, which is
16. The network address is thus Head.0.0/16. The following TLV
Block (content length 8 octets) includes one TLV that indicates that
the originating router is a gateway to this network, at a given
number of hops distance (Value Length 1 octet). The TLV Flags octet
value of 16 again indicates that a Value, but no indexes are needed.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TC |1 1 1 1 0 0 1 1|0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Originator Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop Limit | Hop Count | Message Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1| INTERVAL_TIME |0 0 0 1 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 1| Value | VALIDITY_TIME |0 0 0 1 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 1| Value | CONT_SEQ_NUM |0 0 0 1 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 1 0| Value (ANSN) |0 0 0 0 0 0 1 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0 0 0 0 0|0 0 0 0 0 0 1 0| Head |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mid | Mid |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mid |0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NBR_ADDR_TYPE |0 0 0 1 0 0 0 0|0 0 0 0 0 0 0 1| ROUTABLE_ORIG |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 1|1 0 1 1 0 0 0 0|0 0 0 0 0 0 1 0| Head |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Head (cont) |0 0 0 0 0 0 1 0|0 0 0 1 0 0 0 0|0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 1 0 0| GATEWAY |0 0 0 1 0 0 0 0|0 0 0 0 0 0 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number Hops |
+-+-+-+-+-+-+-+-+
Appendix D. Constraints
Any process which updates the Local Information Base, the
Neighborhood Information Base or the Topology Information Base MUST
ensure that all constraints specified in this appendix are
maintained, as well as those specified in [NHDP].
In each Originator Tuple:
o O_orig_addr MUST NOT equal any other O_orig_addr.
o O_orig_addr MUST NOT equal this router's originator address.
In each Local Attached Network Tuple:
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o AL_net_addr MUST NOT equal any other AL_net_addr.
o AL_net_addr MUST NOT be in the I_local_iface_addr_list of any
Local Interface Tuple or equal the IR_local_iface_addr of any
Removed Interface Address Tuple.
o AL_net_addr MUST not equal this router's originator address, or
equal the O_orig_addr in any Originator Tuple.
o AL_dist MUST NOT be less than zero.
In each Link Tuple:
o L_neighbor_iface_addr_list MUST NOT contain the AL_net_addr of any
Local Attached Network Tuple.
In each Neighbor Tuple:
o N_orig_addr MUST NOT be changed to unknown.
o N_orig_addr MUST NOT equal this router's originator address, or
equal O_orig_addr in any Originator Tuple.
o N_orig_addr MUST NOT equal the AL_net_addr in any Local Attached
Network Tuple.
o N_neighbor_addr_list MUST NOT contain this router's originator
address, the O_orig_addr in any Originator Tuple, or the
AL_net_addr in any Local Attached Network Tuple.
o If N_orig_addr = unknown, then N_willingness = WILL_NEVER, N_mpr =
false, N_mpr_selector = false, and N_advertised = false.
o If N_willingness MUST be in the range from WILL_NEVER to
WILL_ALWAYS, inclusive.
o If N_mpr = true, then N_symmetric MUST be true and N_willingness
MUST NOT equal WILL_NEVER.
o If N_symmetric = true and N_mpr = false, then N_willingness MUST
NOT equal WILL_ALWAYS.
o If N_mpr_selector = true, then N_symmetric MUST be true and
N_advertised MUST be true.
o If N_advertised = true, then N_symmetric MUST be true.
In each Lost Neighbor Tuple:
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o NL_neighbor_addr MUST NOT equal this router's originator address,
equal the O_orig_addr in any Originator Tuple, or equal the
AL_net_addr in any Local Attached Network Tuple.
In each 2-Hop Tuple:
o N2_2hop_addr MUST NOT equal this router's originator address,
equal the O_orig_addr in any Originator Tuple, or equal the
AL_net_addr in any Local Attached Network Tuple.
In each Advertising Remote Router Tuple:
o AR_orig_addr MUST NOT be in the I_local_iface_addr_list in any
Local Interface Tuple or equal the IR_local_iface_addr in any
Removed Interface Address Tuple.
o AR_orig_addr MUST NOT equal this router's originator address or
equal the O_orig_addr in any Originator Tuple.
o AR_orig_addr MUST NOT equal the AL_net_addr in any Local Attached
Network Tuple.
o AR_orig_addr MUST NOT equal the AR_orig_addr in any other
Advertising Remote Router Tuple.
In each Router Topology Tuple:
o There MUST be an Advertising Remote Router Tuple with AR_orig_addr
= TR_from_orig_addr.
o TR_to_orig_addr MUST NOT be in the I_local_iface_addr_list in any
Local Interface Tuple or equal the IR_local_iface_addr in any
Removed Interface Address Tuple.
o TR_to_orig_addr MUST NOT equal this router's originator address or
equal the O_orig_addr in any Originator Tuple.
o TR_to_orig_addr MUST NOT equal the AL_net_addr in any Local
Attached Network Tuple.
o The ordered pair (TR_from_orig_addr, TR_to_orig_addr) MUST NOT
equal the corresponding pair for any other Router Topology Tuple.
o TR_seq_number MUST NOT be greater than AR_seq_number in the
Advertising Remote Router Tuple with AR_orig_addr =
TR_from_orig_addr.
In each Routable Address Topology Tuple:
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o There MUST be an Advertising Remote Router Tuple with AR_orig_addr
= TA_from_orig_addr.
o TA_dest_addr MUST be routable.
o TA_dest_addr MUST NOT be in the I_local_iface_addr_list in any
Local Interface Tuple or equal the IR_local_iface_addr in any
Removed Interface Address Tuple.
o TA_dest_addr MUST NOT equal this router's originator address or
equal the O_orig_addr in any Originator Tuple.
o TA_dest_addr MUST NOT equal the AL_net_addr in any Local Attached
Network Tuple.
o The ordered pair (TA_from_orig_addr, TA_dest_addr) MUST NOT equal
the corresponding pair for any other Attached Network Tuple.
o TA_seq_number MUST NOT be greater than AR_seq_number in the
Advertising Remote Router Tuple with AR_orig_addr =
TA_from_orig_addr.
In each Attached Network Tuple:
o There MUST be an Advertising Remote Router Tuple with AR_orig_addr
= AN_orig_addr.
o AN_net_addr MUST NOT be in the I_local_iface_addr_list in any
Local Interface Tuple or equal the IR_local_iface_addr in any
Removed Interface Address Tuple.
o AN_net_addr MUST NOT equal this router's originator address or
equal the O_orig_addr in any Originator Tuple.
o AN_net_addr MUST NOT equal the AL_net_addr in any Local Attached
Network Tuple.
o The ordered pair (AN_orig_addr, AN_net_addr) MUST NOT equal the
corresponding pair for any other Attached Network Tuple.
o AN_seq_number MUST NOT be greater than AR_seq_number in the
Advertising Remote Router Tuple with AR_orig_addr = AN_orig_addr.
o AN_dist MUST NOT be less than zero.
In each Received Tuple:
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o RX_orig_addr MUST NOT equal this router's originator address or
the O_orig_addr in any Originator Tuple.
o Each ordered triple (RX_type, RX_orig_addr, RX_seq_number) MUST
NOT equal the corresponding triple for any other Received Tuple in
the same Received Set.
In each Processed Tuple:
o P_orig_addr MUST NOT equal this router's originator address or
equal the O_orig_addr in any Originator Tuple.
o Each ordered triple (P_type, P_orig_addr, P_seq_number) MUST NOT
equal the corresponding triple for any other Processed Tuple.
In each Forwarded Tuple:
o F_orig_addr MUST NOT equal this router's originator address or
equal the O_orig_addr in any Originator Tuple.
o Each ordered triple (F_type, F_orig_addr, F_seq_number) MUST NOT
equal the corresponding triple for any other Forwarded Tuple.
Appendix E. Flow and Congestion Control
Due to its proactive nature, this protocol has a natural control over
the flow of its control traffic. Routers transmit control messages
at predetermined rates specified and bounded by message intervals.
This protocol employs [NHDP] for local signaling, embedding MPR
selection advertisement through a simple Address Block TLV, and
router willingness advertisement (if any) as a single Message TLV.
Local signaling, therefore, shares the characteristics and
constraints of [NHDP].
Furthermore, the use of MPRs can greatly reduce the signaling
overhead from link state information dissemination in two ways,
attaining both flooding reduction and topology reduction. First,
using MPR flooding, the cost of distributing link state information
throughout the network is reduced, as compared to when using classic
flooding, since only MPRs need to forward link state declaration
messages. Second, the amount of link state information for a router
to declare is reduced to need only contain that router's MPR
selectors. This reduces the size of a link state declaration as
compared to declaring full link state information. In particular
some routers may not need to declare any such information. In dense
networks, the reduction of control traffic can be of several orders
of magnitude compared to routing protocols using classical flooding
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[MPR]. This feature naturally provides more bandwidth for useful
data traffic and pushes further the frontier of congestion.
Since the control traffic is continuous and periodic, it keeps the
quality of the links used in routing more stable. However, using
some options, some control messages (HELLO messages or TC messages)
may be intentionally sent in advance of their deadline in order to
increase the responsiveness of the protocol to topology changes.
This may cause a small, temporary, and local increase of control
traffic, however this is at all times bounded by the use of minimum
message intervals.
Authors' Addresses
Thomas Heide Clausen
LIX, Ecole Polytechnique
Phone: +33 6 6058 9349
EMail: T.Clausen@computer.org
URI: http://www.ThomasClausen.org/
Christopher Dearlove
BAE Systems ATC
Phone: +44 1245 242194
EMail: chris.dearlove@baesystems.com
URI: http://www.baesystems.com/
Philippe Jacquet
Project Hipercom, INRIA
Phone: +33 1 3963 5263
EMail: philippe.jacquet@inria.fr
The OLSRv2 Design Team
MANET Working Group
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