Mobile Ad hoc Networking (MANET) T. Clausen
Internet-Draft LIX, Ecole Polytechnique, France
Expires: December 21, 2006 C. Dearlove
BAE Systems Advanced Technology
Centre
J. Dean
Naval Research Laboratory
The OLSRv2 Design Team
MANET Working Group
June 19, 2006
MANET Neighborhood Discovery Protocol (NHDP)
draft-ietf-manet-nhdp-00
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Abstract
This document describes a neighborhood discovery protocol (NHDP) for
a mobile ad hoc network (MANET). The protocol provides each MANET
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node with local topology up to two hops distant, describing a node's
1-hop neighbors and symmetric 2-hop neighbors. This is achieved
through periodic message exchange. This neighborhood discovery
protocol may be used by any MANET protocols which need neighborhood
information.
The protocol imposes minimum requirements to the network by not
requiring sequenced or reliable transmission of control traffic.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Applicability Statement . . . . . . . . . . . . . . . . . 5
2. Protocol Overview and Functioning . . . . . . . . . . . . . . 7
3. Neighborhood Information Base . . . . . . . . . . . . . . . . 9
3.1. Link Set . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. Symmetric Neighbor Set . . . . . . . . . . . . . . . . . . 10
3.3. Neighborhood Address Association Set . . . . . . . . . . . 11
3.4. 2-Hop Neighbor Set . . . . . . . . . . . . . . . . . . . . 11
4. Packets and Messages . . . . . . . . . . . . . . . . . . . . . 13
4.1. HELLO Messages . . . . . . . . . . . . . . . . . . . . . . 13
4.1.1. Local Interface Block . . . . . . . . . . . . . . . . 14
4.1.2. Message TLVs . . . . . . . . . . . . . . . . . . . . . 14
4.1.3. Address Block TLVs . . . . . . . . . . . . . . . . . . 16
5. HELLO Message Generation . . . . . . . . . . . . . . . . . . . 17
5.1. HELLO Message: Transmission . . . . . . . . . . . . . . . 18
6. HELLO Message Processing . . . . . . . . . . . . . . . . . . . 19
6.1. Populating the Link Set . . . . . . . . . . . . . . . . . 19
6.2. Populating the Symmetric Neighbor Set . . . . . . . . . . 20
6.3. Populating the Neighborhood Address Association Set . . . 21
6.4. Populating the 2-Hop Neighbor Set . . . . . . . . . . . . 22
6.5. Neighborhood Changes . . . . . . . . . . . . . . . . . . . 23
7. Proposed Values for Constants . . . . . . . . . . . . . . . . 24
7.1. Message Intervals . . . . . . . . . . . . . . . . . . . . 24
7.2. Holding Times . . . . . . . . . . . . . . . . . . . . . . 24
7.3. Time . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
8.1. Multicast Addresses . . . . . . . . . . . . . . . . . . . 25
8.2. Message Types . . . . . . . . . . . . . . . . . . . . . . 25
8.3. TLV Types . . . . . . . . . . . . . . . . . . . . . . . . 25
8.4. LINK_STATUS and OTHER_NEIGHB Values . . . . . . . . . . . 26
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 27
9.1. Normative References . . . . . . . . . . . . . . . . . . . 27
9.2. Informative References . . . . . . . . . . . . . . . . . . 27
Appendix A. Heuristics for Generating HELLO Messages . . . . . . 28
Appendix B. HELLO Message Example . . . . . . . . . . . . . . . . 31
Appendix C. Security Considerations . . . . . . . . . . . . . . . 33
Appendix D. Flow and Congestion Control . . . . . . . . . . . . . 35
Appendix E. Contributors . . . . . . . . . . . . . . . . . . . . 36
Appendix F. Acknowledgements . . . . . . . . . . . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38
Intellectual Property and Copyright Statements . . . . . . . . . . 39
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1. Introduction
This document describes a neighborhood discovery protocol (NHDP) for
a mobile ad hoc network (MANET). It was originally developed for the
Optimized Link State Routing Protocol version 2 (OLSRv2) [3], based
on that used in the Optimized Link State Routing Protocol version 1
[4]. It uses an exchange of HELLO messages in order that each node
can determine its neighborhood up to two hops distant. This protocol
is used by OLSRv2 to determine a node's 1-hop neighbors for routing,
and to allow the selection of MultiPoint Relays (MPRs) for optimized
flooding and topology reporting. This specification however only
describes the message exchange and information storage required for
1-hop and symmetric 2-hop neighborhood discovery. It may be used by
any MANET protocols which need neighborhood information, and which
may add an MPR mechanism, or an alternative to it, using appropriate
TLVs (type-length-value objects) as specified in [1], using which
this protocol's HELLO message format is defined.
This protocol makes no assumptions about the underlying link layer,
other than support of local multicast. Link layer information and
notifications may be used if available and applicable to qualify the
neighborhood information.
1.1. Terminology
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [2].
Additionally, this document uses the following terminology:
node - A MANET router which implements this neighborhood discovery
protocol.
MANET interface - A network device participating in a MANET and using
this neighborhood discovery protocol. A node may have several
MANET interfaces, each interface being assigned one or more IP
addresses.
link - A link is a pair of MANET interfaces from two different nodes,
where at least one interface is able to hear (i.e. receive traffic
from) the other.
symmetric link - A link where both MANET interfaces are able to hear
(i.e. receive traffic from) the other.
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asymmetric link - A link which is not symmetric.
1-hop neighbor - A node X is a 1-hop neighbor of a node Y if node Y
can hear node X (i.e. a link exists from a MANET interface on node
X to a MANET interface on node Y).
symmetric 1-hop neighbor - A node X is a symmetric 1-hop neighbor of
a node Y if a symmetric link exists from a MANET interface on node
X to a MANET interface on node Y.
symmetric 2-hop neighbor - A node X is a symmetric 2-hop neighbor of
a node Y if node X is a symmetric 1-hop neighbor of a symmetric
1-hop neighbor of node Y, but is not node Y itself.
1-hop neighborhood - The 1-hop neighborhood of a node X is the set of
the 1-hop neighbors of node X.
symmetric 1-hop neighborhood - The symmetric 1-hop neighborhood of a
node X is the set of the symmetric 1-hop neighbors of node X.
symmetric 2-hop neighborhood - The symmetric 2-hop neighborhood of a
node X is the set of the symmetric 2-hop neighbors of node X.
(This may include nodes in the 1-hop neighborhood, or even in the
symmetric 1-hop neighborhood, of node X.)
1.2. Applicability Statement
This neighborhood discovery protocol supports nodes which have one or
more interfaces which participate in the MANET. It provides each
node with local topology information up to two hops away. This
information is made available to other protocols through a collection
of sets describing the node's 1-hop neighborhood and symmetric 2-hop
neighborhood, collectively known as the neighborhood information
base.
The specification is designed specifically with IP (IPv4/IPv6) in
mind. All addresses within a control message are assumed to be of
the same size, deduced from IP. In the case of mixed IPv6 and IPv4
addresses, IPv4 addresses are carried in IPv6 as specified in [5].
The packets defined by this specification may use any transport
protocol appropriate to the protocol using this specification. When
the diffusion mechanism enabled by this specification is employed,
UDP may be most appropriate.
This protocol uses the message exchange format specified in [1].
This implies that the HELLO messages specified by this protocol may
be extended using the TLV mechanisms described in [1], e.g. to signal
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MPR selection as required by OLSRv2 [3]. This also implies that
neighborhood discovery protocol messages can be transmitted in
packets with messages from other protocols, so long as these
protocols also use [1].
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2. Protocol Overview and Functioning
This protocol consists of a specification of local signaling, which
serves to:
o advertise the presence of a node and its MANET interfaces to
adjacent nodes (1-hop neighbors);
o discover links to adjacent nodes;
o perform bidirectionality (symmetry) checks on the discovered
links;
o advertise discovered links and whether each is symmetric to its
1-hop neighbors and hence discover symmetric 2-hop neighbors;
o maintain an information base consisting of discovered links and
their status, 1-hop neighbors and their MANET interfaces,
symmetric 1-hop neighbors and symmetric 2-hop neighbors.
Signaling consists of a single type of periodically transmitted
message known as a HELLO message. A HELLO message identifies its
originator node and that node's MANET interfaces and addresses. As a
node receives HELLO messages and populates its information base, a
list of 1-hop neighbors' MANET interface addresses and their link
status is included in subsequent HELLO message content. Thus, the
periodic transmission allows nodes to continuously track changes in
their 1-hop and symmetric 2-hop neighborhoods.
Because each node sends HELLO messages periodically, the protocol can
tolerate reasonable message loss without requiring reliable
transmission. Such losses can occur frequently in radio networks due
to collisions or other transmission problems.
The nominal time interval of a node's periodic HELLO transmission is
known as HELLO_INTERVAL and MAY be included in the HELLO message.
The HELLO message MUST include a validity time value that indicates
the length of time for which the message content is to be considered
valid and included in the receiving node's information base. In some
uses the validity time may be a multiple of HELLO_INTERVAL to allow
for lossy exchange of HELLO messages.
HELLO messages MAY, in addition to periodic transmissions, also be
generated as a response to some event (e.g. a change in the
advertised neighborhood indicated by a received HELLO message or by a
layer 2 notification, if available, indicating a change in a link to
a neighbor). However a node MUST respect a minimum interval,
HELLO_MIN_INTERVAL, between successive HELLO message transmissions in
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order to maintain an upper bound on signaling traffic.
This protocol is designed to work in a completely distributed manner
and does not depend on any central entity. This protocol does not
require any changes to the format of IP packets, thus any existing IP
stack can be used as is.
Each MANET node will form estimates of its 1-hop and symmetric 2-hop
neighborhoods as this protocol operates. These estimates can be
maintained in an information base comprised of the data sets listed
below. These are defined formally in Section 3 and can be summarized
as follows:
Link Set - This set records the status of all links from and, if
symmetric, to 1-hop neighbors. It also records as lost links
which used to be symmetric but have since failed. A node MUST
record the Link Set in order to correctly send HELLO messages.
Symmetric Neighbor Set - This set records the addresses of the MANET
interfaces of symmetric 1-hop neighbors, or, as lost, those which
used to be. Note that if any of these nodes have more than one
MANET interface then this set may record addresses that are not in
the Link Set. A node MUST record the Symmetric Neighbor Set in
order to correctly send HELLO messages.
Neighborhood Address Association Set - This set allows the addresses
of the MANET interfaces of each 1-hop neighbor to be associated
with each other. It is required for processes such as MPR
selection as in [3].
2-Hop Neighbor Set - This set records the addresses of the MANET
interfaces of symmetric 2-hop neighbors. It is required for
processes such as MPR selection as in [3].
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3. Neighborhood Information Base
The neighborhood information base stores information about the 1-hop
neighborhood and the symmetric 2-hop neighborhood of a node.
Note that it is possible for a node, X, to be present in both the
1-hop and symmetric 2-hop neighborhoods of another node, Y,
concurrently. If the link between node X and node Y breaks, this
allows node X to be taken into consideration as a symmetric 2-hop
neighbor by node Y immediately, rather than waiting for a HELLO
message exchange cycle.
This specification assumes that all addresses have an associated
prefix length. The prefix length of an address is, in HELLO
messages, indicated using the PREFIX_LENGTH TLV specified in [1]. If
no PREFIX_LENGTH TLV is present for a given address, it is assumed
that the prefix length for that address is equal to the length of the
address. Two addresses are identical if and only if both the
addresses and their associated prefix lengths are identical.
Addresses recorded in the neighborhood information base
(L_local_iface_addr, L_neighbor_iface_addr, N_local_iface_addr,
N_neighbor_iface_addr, N2_local_iface_addr, N2_neighbor_iface_addr,
N2_2hop_iface_addr and those listed in NA_neighbor_iface_addr_list)
MUST all be recorded with prefix lengths, in order to allow
comparison with addresses received in HELLO messages.
3.1. Link Set
A node records a set of "Link Tuples", recording information about
its 1-hop neighborhood:
(L_local_iface_addr, L_neighbor_iface_addr, L_SYM_time,
L_ASYM_time, L_time)
each describing a link between a MANET interface of this node and a
MANET interface of one of its 1-hop neighbors, where:
L_local_iface_addr is the address of the MANET interface of the local
node on which the 1-hop neighbor is or was heard;
L_neighbor_iface_addr is the address of the MANET interface of the
1-hop neighbor;
L_SYM_time is the time until which the link to the 1-hop neighbor is
considered symmetric;
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L_ASYM_time is the time until which the MANET interface of the 1-hop
neighbor is considered heard;
L_time specifies when this Link Tuple expires and MUST be removed.
The status of the link, denoted L_STATUS, can be derived based on the
fields L_SYM_time and L_ASYM_time as defined in Table 1.
+-------------+-------------+-----------+
| L_SYM_time | L_ASYM_time | L_STATUS |
+-------------+-------------+-----------+
| Expired | Expired | LOST |
| | | |
| Not Expired | Expired | SYMMETRIC |
| | | |
| Not Expired | Not Expired | SYMMETRIC |
| | | |
| Expired | Not Expired | HEARD |
+-------------+-------------+-----------+
Table 1
In a node, the set of Link Tuples is denoted the "Link Set".
3.2. Symmetric Neighbor Set
A node records a set of "Symmetric Neighbor Tuples", recording
information about its symmetric 1-hop neighborhood:
(N_local_iface_addr, N_neighbor_iface_addr, N_SYM_time, N_time)
each describing an address of a MANET interface of this node and an
address of a MANET interface of one of its symmetric 1-hop neighbors,
where:
N_local_iface_addr is the address of the MANET interface of the local
node to which the 1-hop neighbor has or had a symmetric link;
N_neighbor_iface_addr is an address of a MANET interface of a 1-hop
neighbor which is or was in this node's symmetric 1-hop
neighborhood;
N_SYM_time is the time until which the 1-hop neighbor is considered
to be in this node's symmetric 1-hop neighborhood;
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N_time specifies when this Symmetric Neighborhood Tuple expires and
MUST be removed.
The status of the 1-hop neighbor, denoted N_STATUS, can be derived
based on the field L_SYM_time as defined in Table 2.
+-------------+-----------+
| N_SYM_time | N_STATUS |
+-------------+-----------+
| Expired | LOST |
| | |
| Not Expired | SYMMETRIC |
+-------------+-----------+
Table 2
In a node, the set of Symmetric Neighbor Tuples is denoted the
"Symmetric Neighbor Set".
3.3. Neighborhood Address Association Set
A node records a set of "Neighborhood Address Association Tuples",
recording information about the MANET interface configuration of its
1-hop neighbors:
(NA_neighbor_iface_addr_list, NA_time)
NA_neighbor_iface_addr_list is a list of interface addresses of a
single 1-hop neighbor;
NA_time specifies when this Neighborhood Address Association Tuple
expires and MUST be removed.
In a node, the set of Neighborhood Address Association Tuples is
denoted the "Neighborhood Address Association Set".
3.4. 2-Hop Neighbor Set
A node records a set of "2-Hop Neighbor Tuples", recording
information about a its symmetric 2-hop neighborhood:
(N2_local_iface_addr, N2_neighbor_iface_addr, N2_2hop_iface_addr,
N2_time)
each describing a symmetric link between an address of a MANET
interface of one of this node's symmetric 1-hop neighbors and an
address of a MANET interface of a node in this node's symmetric 2-hop
neighborhood.
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N2_local_iface_addr is the address of the local MANET interface over
which the information defining this 2-Hop Neighbor Tuple was
received;
N2_neighbor_iface_addr is the address of the MANET interface address
of a symmetric 1-hop neighbor;
N2_2hop_iface_addr is the address of a MANET interface of a symmetric
2-hop neighbor which has a symmetric link (not necessarily using
this address) to the node with MANET interface address
N2_neighbor_iface_addr;
N2_time specifies the time at which this 2-Hop Neighbor Tuple expires
and MUST be removed.
In a node, the set of 2-Hop Neighbor Tuples is denoted the "2-Hop
Neighbor Set".
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4. Packets and Messages
The packet and message format used by this neighborhood discovery
protocol is defined in [1], which is used with the following
considerations:
o this protocol specifies one message type, the HELLO message, in
Section 4.1;
o HELLO message header options may be used as specified by the
protocol which uses this neighborhood discovery protocol;
o HELLO messages are transmitted only one hop, i.e. MUST NOT be
forwarded;
o multi-message packets may be created using other messages as
specified by the protocol which uses this neighborhood discovery
protocol;
o packet header options may be used as specified by the protocol
which uses this neighborhood discovery protocol.
4.1. HELLO Messages
A HELLO message MUST contain:
o a message TLV with Type == VALIDITY_TIME and Value == H_HOLD_TIME,
as specified in Section 4.1.2.1
o an address block known as the Local Interface Block, as specified
in Section 4.1.1; other addresses MUST NOT be added to this
address block.
A HELLO message MAY contain:
o a message TLV with Type == INTERVAL_TIME and Value ==
HELLO_INTERVAL, as specified in Section 4.1.2.2;
o one or more address blocks with associated address block TLVs as
specified in Section 4.1.3; these address blocks contain current
or former 1-hop neighbors' MANET interface addresses with
associated TLVs. Other addresses (i.e. addresses of non-neighbor
nodes) MAY be added to these address blocks, however if they are
then these addresses MUST NOT have associated TLVs from the
address block TLVs specified in Section 4.1.3.
This protocol specifies two message TLVs and three address block TLVs
used in HELLO messages in Section 4.1.2 and Section 4.1.3; other TLVs
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MAY be included as specified by the protocol which uses this
neighborhood discovery protocol.
4.1.1. Local Interface Block
The first address block, plus following TLV block, in a HELLO message
is known as the Local Interface Block. The Local Interface Block is
not distinguished in any way other than by being the first address
block in the message.
The first address of the Local Interface Block MUST contain the used
address of the interface over which the HELLO message is transmitted.
If that interface has an associated prefix different from the length
of the address, a PREFIX_LENGTH TLV MUST be associated with this
address. This first address, with associated prefix length, of the
Local Interface Block is henceforth denoted the "Source Address".
The Local Interface Block MUST contain all of the addresses of all of
the MANET interfaces of the originating node, using the standard
<address-block> syntax specified in [1]. Those addresses, if any,
which correspond to MANET interfaces other than that on which the
HELLO message is transmitted MUST have a corresponding OTHER_IF TLV
as specified in Section 4.1.3, other addresses MUST NOT use this TLV.
Note that a Local Interface Block MAY include more than one address
for each MANET interface, and hence a HELLO message MAY contain more
than one address without an OTHER_IF TLV. A Local Interface Block
MUST NOT contain any addresses which are not of MANET interfaces of
the originating node.
4.1.2. Message TLVs
This section specifies two message TLVs: VALIDITY_TIME and
INTERVAL_TIME.
4.1.2.1. VALIDITY_TIME TLV
All HELLO messages MUST include a VALIDITY_TIME TLV, specifying for
how long a node may, upon receiving a message, consider the message
content to be valid. The VALIDITY_TIME TLV, described in this
document, contains a single value since HELLO messages are
transmitted only one hop. Note that [1] specifies an extended
version of this VALIDITY_TIME TLV, which is compatible with the
format of the VALIDITY_TIME TLV in this specification.
The VALIDITY_TIME message TLV specification is given in Table 3.
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+----------------+------+-------------------+----------------------+
| Name | Type | Length | Value |
+----------------+------+-------------------+----------------------+
| VALIDITY_TIME | TBD | 8 bits | <t_default> |
+----------------+------+-------------------+----------------------+
Table 3
where <t_default> is the period for which the information is valid,
represented as specified in Section 4.1.2.3.
4.1.2.2. INTERVAL_TIME TLV
HELLO messages MAY include an INTERVAL_TIME message TLV, specifying
the interval at which HELLO messages are being generated by the
originator node. Note that HELLO messages which are not part of a
regular schedule SHALL be ignored in defining the interval. If, for
whatever reason, HELLO messages are sent in an irregular pattern,
then this SHALL be the longest interval in that pattern.
The INTERVAL_TIME message TLV specification is given in Table 4.
+----------------+------+-------------------+----------------------+
| Name | Type | Length | Value |
+----------------+------+-------------------+----------------------+
| INTERVAL_TIME | TBD | 8 bits | <time> |
+----------------+------+-------------------+----------------------+
Table 4
where <time> is the scheduled maximum time until the next
transmission of a HELLO message by the originator node on the same
interface, represented as specified in Section 4.1.2.3.
4.1.2.3. Representing Time
Section 4.1.2.1 and Section 4.1.2.2 specify TLVs where time is
represented as a single octet. This is defined by the lowest four
bits of the octet representing the mantissa (a) and the highest four
bits of the octet representing the exponent (b) of the time as a
multiple of a fixed constant C, yielding that:
o time = C * (1 + a/16) * 2^b
where a is the integer represented by the four lowest bits of the
time field and b the integer represented by the four highest bits of
the time field. All nodes in the network MUST use the same value of
C, which will be specified in seconds, hence so will be all times
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(see Section 7). Note that ascending values of the octet represent
ascending values of time, times may thus be compared by comparison of
octets.
An algorithm for computing the representation of time t is the
following:
1. find the largest integer b such that t/C >= 2^b;
2. set a = 16 * (t / (C * 2^b) - 1), rounded up to the nearest
integer;
3. if a == 16 then set b = b + 1 and set a = 0;
4. if a and b are in the range 0 and 15 then t can be represented by
an octet holding the value 16*b + a, otherwise it can not.
As examples, the values of 2 seconds and 6 seconds are represented by
(a=0, b=5) and (a=8, b=6), respectively, i.e., by the octets 80 and
104 (hexadecimal 50 and 68).
4.1.3. Address Block TLVs
The three address block TLVs used in HELLO messages are specified in
Table 5.
+----------------+------+-------------------+-----------------------+
| Name | Type | Length | Value |
+----------------+------+-------------------+-----------------------+
| OTHER_IF | TBD | 0 bits | Not Applicable |
| | | | |
| LINK_STATUS | TBD | 8 bits | One of LOST, |
| | | | SYMMETRIC or HEARD. |
| | | | |
| OTHER_NEIGHB | TBD | 8 bits | One of LOST or |
| | | | SYMMETRIC |
+----------------+------+-------------------+-----------------------+
Table 5
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5. HELLO Message Generation
HELLO messages MUST be generated and transmitted independently on
each MANET interface. The maximum interval between HELLO
transmissions on the same MANET interface MUST NOT exceed
HELLO_MIN_INTERVAL. Two successive HELLO message transmissions on
the same MANET interface MUST be separated by at least
HELLO_MIN_INTERVAL.
Each HELLO message MUST include a Local Interface Block as specified
in Section 4.1.1 as its first address block.
On its MANET interface with address Sending Address, a node MUST
report appropriate addresses with associated TLVs from the Link Set
and Symmetric Neighbor Set. These addresses, with their associated
TLVs, MAY be reported in any HELLO messages transmitted on that MANET
interface. All such addresses, with their associated TLVs, MUST be
reported in at least one HELLO message transmitted on that MANET
interface within every interval of length REFRESH_INTERVAL. These
addresses MUST NOT be included in the Local Interface Block, they MAY
be included in any other address block.
The addresses, with their associated TLVs, which MUST be included in
HELLO messages over the local MANET interface with address Sending
Address, are computed thus:
1. For each Link Tuple with L_local_iface_addr == Sending Address,
include:
* L_neighbor_iface_addr with an associated TLV with:
+ Type = LINK_STATUS; AND
+ Value = L_STATUS.
2. For each address which appears as an N_neighbor_iface_addr in one
or more Symmetric Neighbor Tuples:
1. if this address has already been included with an associated
TLV with Type == LINK_STATUS and Value == SYMMETRIC, do not
add an associated TLV with Type == OTHER_NEIGHB;
2. otherwise if, for one or more of these Symmetric Neighbor
Tuples, N_STATUS == SYMMETRIC, then include this address with
associated TLV with:
+ Type = OTHER_NEIGHB; AND
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+ Value = SYMMETRIC;
3. otherwise if, for all of these Symmetric Neighbor Tuples,
N_STATUS == LOST, and this address has not already been
included with an associated TLV with Type == LINK_STATUS and
Value == LOST, then include this address with associated TLV
with:
+ Type = OTHER_NEIGHB; AND
+ Value = LOST.
If an address is specified as included with more than one associated
TLV, then these TLVs MAY be independently included or excluded from
HELLO messages as long as all are included with any interval of
length REFRESH_INTERVAL. TLVs applying to the same address MAY be
applied to the same or different copies of the address in a given
HELLO message.
5.1. HELLO Message: Transmission
Messages are transmitted in the packet/message format specified by
[1] using the ALL-MANET-NEIGHBORS multicast address as destination IP
address and with the HELLO message Hop Limit = 1.
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6. HELLO Message Processing
On receiving a HELLO message, a node will update its neighborhood
information base according to the specification given in this
section.
For the purpose of this section, note the following definitions:
o the "validity time" of a message is calculated from the
VALIDITY_TIME TLV of the message as specified in Section 4.1.2.1;
o the "Source Address" is the first address, including prefix
length, of the Local Interface Block in the HELLO message;
o the "Receiving Address" is the address, including prefix length,
of the MANET interface on which the HELLO message was received;
o the word EXPIRED indicates that a timer is set to a value clearly
preceding the current time (e.g. current time - 1).
6.1. Populating the Link Set
On receiving a HELLO message, a node SHOULD update its Link Set:
1. If there is no Link Tuple with:
* L_local_iface_addr == Receiving Address; AND
* L_neighbor_iface_addr == Source Address,
then create a new Link Tuple with
* L_local_iface_addr = Receiving Address;
* L_neighbor_iface_addr = Source Address;
* L_SYM_time = EXPIRED;
* L_time = current time + validity time.
2. This Link Tuple (existing or new) is then modified as follows:
1. If the node finds the Receiving Address in one of the address
blocks included in the HELLO message, other than the Local
Interface Block, then the Link Tuple is modified as follows:
1. If the Receiving Address in that address block is
associated with a TLV with Type == LINK_STATUS and Value
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== LOST then:
1. if L_STATUS == SYMMETRIC:
o L_time = current time + max(validity time,
L_HOLD_TIME),
o L_SYM_time = EXPIRED.
2. Otherwise if the Receiving Address in that address block
is associated with a TLV with Type == LINK_STATUS and
(Value == HEARD or Value == SYMMETRIC) then:
- L_SYM_time = current time + validity time;
- L_time = L_SYM_time + L_HOLD_TIME.
2. L_ASYM_time = current time + validity time;
3. L_time = max(L_time, L_ASYM_time).
6.2. Populating the Symmetric Neighbor Set
On receiving a HELLO message, a node SHOULD update its Symmetric
Neighbor Set:
1. If the Receiving Address is in an address block of the HELLO
message, other than the Local Interface Block, with an associated
TLV with Type == LINK_STATUS and (Value == HEARD or Value ==
SYMMETRIC) then:
1. For each address (henceforth neighbor address) in the HELLO
message's Local Interface Block:
1. If there is a Symmetric Neighbor Tuple with:
- N_local_iface_addr == Receiving Address; AND
- N_neighbor_iface_addr == neighbor address,
then update this Symmetric Neighbor Tuple to have:
- N_SYM_time = current time + validity time;
- N_time = N_SYM_time + N_HOLD_TIME.
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2. Otherwise create a new Symmetric Neighbor Tuple with:
- N_local_iface_addr = Receiving Address;
- N_neighbor_iface_addr = neighbor address;
- N_SYM_time = current time + validity time;
- N_time = N_SYM_time + N_HOLD_TIME.
2. Otherwise if the Receiving Address is in an address block of the
HELLO message, other than the Local Interface Block, with an
associated TLV with Type == LINK_STATUS and Value == LOST, then:
1. For each address (henceforth neighbor address) in the HELLO
message Local Interface Block, if there exists a Symmetric
Neighbor Tuple with:
+ N_local_iface_addr == Receiving Address; AND
+ N_neighbor_iface_addr == neighbor address,
update this Symmetric Neighbor Tuple to have:
+ N_SYM_time = EXPIRED;
+ N_time = min(N_time, current time + N_HOLD_TIME).
6.3. Populating the Neighborhood Address Association Set
On receiving a HELLO message, the node SHOULD update its Neighborhood
Address Association Set:
1. Remove all Neighborhood Address Association Tuples where:
* NA_neighbor_iface_addr_list contains at least one address
which is contained in the Local Interface Block of the
received HELLO message,
and create a new Neighborhood Address Association Tuple with:
* NA_neighbor_iface_addr_list = list of all addresses contained
in the Local Interface Block of the received HELLO message;
* NA_time = current time + validity time.
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6.4. Populating the 2-Hop Neighbor Set
On receiving a HELLO message the node SHOULD update its 2-Hop
Neighbor Set:
1. If there exists a Link Tuple with L_local_iface_addr == Source
Address and L_STATUS == SYMMETRIC then:
1. For each address (henceforth 2-hop neighbor address) in an
address block of the HELLO message, other than the Local
Interface Block, which is not an interface address of the
receiving node:
1. If the 2-hop neighbor address has an associated TLV with:
- Type == LINK_STATUS and Value == SYMMETRIC; OR
- Type == OTHER_NEIGHB and Value == SYMMETRIC,
then, if there is no 2-Hop Neighbor Tuple with:
- N2_local_iface_addr == Receiving Address;
- N2_neighbor_iface_addr == Source Address;
- N2_2hop_iface_addr == 2-hop neighbor address;
create a 2-Hop Neighbor Tuple with:
- N2_local_iface_addr = Receiving Address; AND
- N2_neighbor_iface_addr = Source Address; AND
- N2_2hop_iface_addr = 2-hop neighbor address.
This 2-Hop Neighbor Tuple (existing or new) is then
modified as follows:
- N2_time = current time + validity time.
2. Otherwise if the 2-hop neighbor address has a TLV with:
- Type == LINK_STATUS and (Value == LOST or Value ==
HEARD); OR
- Type == OTHER_NEIGHB and Value == LOST;
then remove all 2-Hop Neighbor Tuples with:
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- N2_local_iface_addr == Receiving Address; AND
- N2_neighbor_iface_addr == Source Address; AND
- N2_2hop_iface_addr == 2-hop neighbor address.
6.5. Neighborhood Changes
If the L_SYM_time field of a Link Tuple expires (either due to timing
out, or as a result of processing a TLV with Type == LINK_STATUS and
Value == LOST) then all 2-Hop Neighbor Tuples with:
o N2_local_iface_addr == L_local_iface_addr from the Link Tuple,
AND;
o N2_neighbor_iface_addr == L_neighbor_iface_addr from the Link
Tuple,
MUST be deleted.
In this, or any other case of neighborhood change, a node MAY send a
HELLO message reporting updated information. If a node does send
such a HELLO message the node MUST ensure that any two successive
HELLO messages are separated by at least HELLO_MIN_INTERVAL.
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7. Proposed Values for Constants
This section list the values for the constants used in the
description of the protocol.
7.1. Message Intervals
o HELLO_INTERVAL = 2 seconds
o REFRESH_INTERVAL = HELLO_INTERVAL
o HELLO_MIN_INTERVAL = HELLO_INTERVAL/4
7.2. Holding Times
o H_HOLD_TIME = 3 x REFRESH_INTERVAL
o L_HOLD_TIME = H_HOLD_TIME
o N_HOLD_TIME = H_HOLD_TIME
7.3. Time
o C = 0.0625 seconds (1/16 second)
In order to achieve interoperability, C MUST be the same on all
nodes.
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8. IANA Considerations
8.1. Multicast Addresses
A well-known multicast address, ALL-MANET-NEIGHBORS, must be
registered and defined for both IPv6 and IPv4. The addressing scope
is link-local, i.e. this address is similar to the all nodes/routers
multicast address of IPv6 in that it targets all MANET nodes adjacent
to the originator of an IP datagram.
8.2. Message Types
This specification defines one message type, which must be allocated
from the "Assigned Message Types" repository of [1]
+--------------------+-------+--------------------------------------+
| Mnemonic | Value | Description |
+--------------------+-------+--------------------------------------+
| HELLO | TBD | Local Signaling |
+--------------------+-------+--------------------------------------+
Table 6
8.3. TLV Types
This specification defines two Message TLV types, which must be
allocated from the "Assigned Message TLV Types" repository of [1]
+--------------------+-------+--------------------------------------+
| Mnemonic | Value | Description |
+--------------------+-------+--------------------------------------+
| VALIDITY_TIME | TBD | The time (in seconds) from receipt |
| | | of the message during which the |
| | | information contained in the message |
| | | is to be considered valid |
| | | |
| INTERVAL_TIME | TBD | The maximum time (in seconds) |
| | | between two successive transmissions |
| | | of messages of the appropriate type |
+--------------------+-------+--------------------------------------+
Table 7
This specification defines three Address Block TLV types, which must
be allocated from the "Assigned Address Block TLV Types" repository
of [1]
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+--------------------+-------+--------------------------------------+
| Mnemonic | Value | Description |
+--------------------+-------+--------------------------------------+
| OTHER_IF | TBD | Specifies that the address, in the |
| | | Local Interface Block of the |
| | | message, is an address associated |
| | | with a MANET interface other than |
| | | the one on which the message is |
| | | transmitted |
| | | |
| LINK_STATUS | TBD | Specifies a given link's status |
| | | (LOST, SYMMETRIC or HEARD) |
| | | |
| OTHER_NEIGHB | TBD | Specifies that the address is, or |
| | | was, of a MANET interface of a |
| | | symmetric 1-hop neighbor of the node |
| | | transmitting the HELLO message, but |
| | | does not have a matching or better |
| | | LINK_STATUS TLV |
+--------------------+-------+--------------------------------------+
Table 8
8.4. LINK_STATUS and OTHER_NEIGHB Values
The values which the LINK_STATUS TLV can use are the following:
o LOST = 0
o SYMMETRIC = 1
o HEARD = 2
The values which the OTHER_NEIGHB TLV can use are the following:
o LOST = 0
o SYMMETRIC = 1
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9. References
9.1. Normative References
[1] Clausen, T., Dean, J., Dearlove, C., and C. Adjih, "Generalized
MANET Packet/Message Format", Work In
Progress draft-ietf-manet-packetbb-01.txt, June 2006.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", RFC 2119, BCP 14, March 1997.
9.2. Informative References
[3] Clausen, T., Dearlove, C., and P. Jacquet, "The Optimized Link
State Routing Protocol version 2", Work In
Progress draft-ietf-manet-olsrv2-02.txt, June 2006.
[4] Clausen, T. and P. Jacquet, "The Optimized Link State Routing
Protocol", RFC 3626, October 2003.
[5] Hinden, R. and S. Deering, "Internet Protocol Version 6 (IPv6)
Addressing Architecture", RFC 3513, April 2003.
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Appendix A. Heuristics for Generating HELLO Messages
The algorithm for generating HELLO messages in Section 5 specifies
which addresses MAY be included in the address blocks after the Local
Interface Block, and with which associated TLVs. These TLVs may have
Type == LINK_STATUS or Type == OTHER_NEIGHB, or both. TLVs with Type
== LINK_STATUS may have three possible values (Value == HEARD, Value
== SYMMETRIC or Value == LOST), and TLVs of TYPE == OTHER_NEIGHB may
have two possible values (Value == SYMMETRIC or Value == LOST). When
both TLVs are associated with the same address only certain
combinations of these TLV values are necessary, and are the only
combinations generated by the algorithm in Section 5. These
combinations are indicated in Table 9.
Cells labeled with "Yes" indicate the possible combinations which are
generated by the algorithm in Section 5. Cells labeled with "No"
indicate combinations not generated by the algorithm in Section 5,
but which are correctly parsed and interpreted by the algorithm in
Section 6.
+----------------+----------------+----------------+----------------+
| | Type == | Type == | Type == |
| | OTHER_NEIGHB | OTHER_NEIGHB, | OTHER_NEIGHB, |
| | (absent) | Value == | Value == LOST |
| | | SYMMETRIC | |
+----------------+----------------+----------------+----------------+
| Type == | No | Yes | Yes |
| LINK_STATUS | | | |
| (absent) | | | |
| | | | |
| Type == | Yes | Yes | Yes |
| LINK_STATUS, | | | |
| Value == HEARD | | | |
| | | | |
| Type == | Yes | No | No |
| LINK_STATUS, | | | |
| Value == | | | |
| SYMMETRIC | | | |
| | | | |
| Type == | Yes | Yes | No |
| LINK_STATUS, | | | |
| Value == LOST | | | |
+----------------+----------------+----------------+----------------+
Table 9
In creating the HELLO message there are three stages:
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1. collect the addresses into groups, each of which will form an
address block (this heuristic assumes that each address will be
included only once in a HELLO message, and that all TLVs
associated with it are included);
2. order the addresses in each group for most efficient TLV
association;
3. add the TLVs in the most efficient manner, whether single or
multiple value.
There is no straightforward way to perform these steps to create the
most optimal (smallest) HELLO message. Instead the following
heuristics may be considered:
1. The easiest approach to grouping addresses is to put them all in
a single address block. Separate address blocks are appropriate
when addresses have significantly different initial (head) bit
sequences, and the address compression in the address block
construction can be more efficient when addresses with different
initial sequences can be compressed separately, gaining more than
the overhead of multiple address blocks. Separate address blocks
have a lower overhead when either they use different TLVs, or
when they use multivalue TLVs. The simplest heuristic is to use
a single address block, unless addresses may be divided into one
or more subnets, especially if these are associated with
different MANET interfaces and hence each uses either LINK_STATUS
or OTHER_NEIGHB TLVs, but not both.
2. Grouping addresses that use a single TLV is straightforward, so
that each TLV type and value may be applied to a continuous
sequence of addresses. This can be extended to cover the case
where addresses have more than one TLV. An example of how to
order all TLV combinations so that each TLV type and value is
applied to a continuous sequence of addresses is given. (This
order is not unique.)
* Type == LINK_STATUS, Value == LOST.
* Type == LINK_STATUS, Value == LOST and Type == OTHER_NEIGHB,
Value == SYMMETRIC.
* Type == OTHER_NEIGHB, Value == SYMMETRIC.
* Type == LINK_STATUS, Value == HEARD and Type == OTHER_NEIGHB,
Value == SYMMETRIC.
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* Type == LINK_STATUS, Value == HEARD.
* Type == LINK_STATUS, Value == HEARD and Type == OTHER_NEIGHB,
Value == LOST.
* Type == OTHER_NEIGHB, Value == LOST.
* Type == LINK_STATUS, Value == SYMMETRIC.
This order is not appropriate when multiple value TLVs are to be
used, then it is more important to group all TLVs of the same
type together, even when having different values. A possible
ordering is
* Type == LINK_STATUS, Value == HEARD.
* Type == LINK_STATUS, Value == SYMMETRIC.
* Type == LINK_STATUS, Value == LOST.
* Type == LINK_STATUS, Value == HEARD and Type == OTHER_NEIGHB,
Value == SYMMETRIC.
* Type == LINK_STATUS, Value == HEARD and Type == OTHER_NEIGHB,
Value == LOST.
* Type == LINK_STATUS, Value == LOST and Type == OTHER_NEIGHB,
Value == SYMMETRIC.
* Type == OTHER_NEIGHB, Value == SYMMETRIC.
* Type == OTHER_NEIGHB, Value == LOST.
Where one TLV type uses single values and the other multiple
values, appropriate orderings can be devised.
3. When there are many addresses in an address block, the most
efficient way to add TLVs is as up to five single value TLVs,
each with a single octet value field. When there are few
addresses in an address block, the most efficient way to add TLVs
is as up to two multiple value TLVs, with one octet of value per
address each. It may be appropriate to use one approach for each
TLV type. It is relatively straightforward to estimate the cost
of each approach (adding TLV type, semantics, length and index
overheads per TLV, and either one octet per value or per address
as appropriate) and to select the probably lower cost approach.
Alternatively a single decision based on the expected number of
1-hop neighbor addresses may be made.
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Appendix B. HELLO Message Example
A simple example HELLO message, sent by an originator node with a
single MANET interface, is as follows. The message uses IPv4 (four
octet) addresses without prefix TLVs, i.e. with all addresses having
maximum length prefixes. The message is sent with a full message
header (message semantics octet is 0) with a hop limit of 1 and a hop
count of 0. The overall message length is 48 octets (it does not
need padding).
The message has a message TLV block with content length 8 octets
containing two message TLVs, of types VALIDITY_TIME and
INTERVAL_TIME. Each uses a TLV with semantics value 4, indicating no
start and stop indexes are included, and each has a value length of 1
octet. The values included (0x68 and 0x50) represent the default
values of 6 seconds and 2 seconds, respectively.
The first address block contains 1 local interface address, with head
length 4 and no address tail or mid parts. This address block has no
TLVs (TLV block content length 0 octets).
The second, and last, address block contains 4 neighbor interface
addresses, with head length 3 octets, no address tail part and each
address mid part having length one octet. The following TLV block
(content length 7 octets) includes one TLV which reports the link
status of all neighbors in a single multivalue TLV: the first two
addresses are HEARD, the third address is SYMMETRIC and the fourth
address is LOST. The TLV semantics value of 12 indicates, in
addition to that this is a multivalue TLV, that no start and stop
indexes are included, since values for all addresses are included.
The TLV value length of 4 octets indicates one octet per value per
address.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HELLO |0 0 0 0 0 0 0 0|0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Originator Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 1|0 0 0 0 0 0 0 0| Message Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0| VALIDITY_TIME |0 0 0 0 0 1 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 1|0 1 1 0 1 0 0 0| INTERVAL_TIME |0 0 0 0 0 1 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 1|0 1 0 1 0 0 0 0|0 0 0 0 0 0 0 1|0 0 0 0 0 1 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Head |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0|0 0 0 0 0 1 0 0|0 0 0 0 0 0 1 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Head | Mid |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mid | Mid | Mid |0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 1 1 1| LINK_STATUS |0 0 0 0 1 1 0 0|0 0 0 0 0 1 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HEARD | HEARD | SYMMETRIC | LOST |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Appendix C. Security Considerations
The objective of this protocol is to allow each node in the network
to acquire information describing its 1-hop and symmetric 2-hop
neighborhoods. This is acquired through periodic message exchange
between neighboring nodes, and the information is made available
through a collection of sets, describing the node's 1-hop
neighborhood and symmetric 2-hop neighborhood.
Under normal circumstances, the information recorded in these sets is
correct - i.e. corresponds to the actual network topology, apart from
any changes which have not (yet) been tracked by the HELLO message
exchanges. If some node for some reason, malice or malfunction,
inject invalid HELLO messages, incorrect information may be recorded
in the sets maintained.
A correctly formed, but still invalid, HELLO message may take any of
the following forms:
1. The Local Interface Block of the HELLO message may contain
addresses which do not correspond to addresses of MANET
interfaces of the local node which transmits the HELLO message;
2. The Local Interface Block of the HELLO message may omit
addresses of MANET interfaces of the local node which transmits
the HELLO message;
3. The Local Interface Block may contain OTHER_IF TLVs, indicating
incorrectly that an address is associated with a MANET interface
other than the one over which the HELLO message is being
transmitted;
4. The Local Interface Block may omit OTHER_IF TLVs, thereby
indicating incorrect addresses associated with the MANET
interface over which the HELLO message is being transmitted;
5. A present or absent address in an address block, other than in
the Local Interface Block, does not in and by itself cause a
problem. It is the presence, absence or incorrectness of
associated LINK_STATUS and OTHER_NEIGHB TLVs that cause
problems;
6. A present LINK_STATUS TLV may, incorrectly, identify an address
as being of a node which is or was in the sending node's 1-hop
neighborhood;
7. A consistently absent LINK_STATUS TLV may, incorrectly, fail to
identify an address as being of a node which is or was in the
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sending node's 1-hop neighborhood;
8. A present OTHER_NEIGHB TLV may, incorrectly, identify an address
as being of a node which is or was in the sending node's
symmetric 1-hop neighborhood;
9. A consistently absent OTHER_NEIGHB TLV may, incorrectly, fail to
identify an address as being of a node which is or was in the
sending node's symmetric 1-hop neighborhood;
10. The value of a LINK_STATUS or OTHER_NEIGHB TLV may incorrectly
indicate the status (LOST, SYMMETRIC, HEARD) of a 1-hop
neighbor.
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Appendix D. Flow and Congestion Control
This document specifies one message type, HELLO messages. The size
of each complete HELLO message is proportional to the size of the
transmitting node's 1-hop neighborhood (this information may be sent
distributed across multiple interfaces). HELLO messages MUST NOT be
forwarded.
A node MUST report its 1-hop neighborhood in HELLO messages on each
of its MANET interfaces at least each REFRESH_INTERVAL. Thus, this
puts a lower bound on the control traffic, which each node employing
this neighborhood discovery protocol in the network generates.
A node MUST ensure that two successive HELLO messages sent on the
same MANET interface are separated by at least HELLO_MIN_INTERVAL.
Thus, this puts an upper bound on the control traffic, which each
node employing this neighborhood discovery protocol in the network
generates.
In order for the protocol to function, each node in the network MUST
employ the HELLO signaling as described in this specification.
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Appendix E. Contributors
This specification is the result of the joint efforts of the
following contributors -- listed alphabetically.
o Brian Adamson, NRL, USA, <adamson@itd.nrl.navy.mil>
o Cedric Adjih, INRIA, France, <Cedric.Adjih@inria.fr>
o Emmanuel Baccelli, Hitachi Labs Europe, France,
<Emmanuel.Baccelli@inria.fr>
o Thomas Heide Clausen, PCRI, France, <T.Clausen@computer.org>
o Justin Dean, NRL, USA, <jdean@itd.nrl.navy.mil>
o Christopher Dearlove, BAE Systems, UK,
<Chris.Dearlove@baesystems.com>
o Philippe Jacquet, INRIA, France, <Philippe.Jacquet@inria.fr>
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Appendix F. Acknowledgements
The authors would like to acknowledge the team behind OLSRv1,
specified in RFC3626, including Anis Laouiti, Pascale Minet, Laurent
Viennot (all at INRIA, France), and Amir Qayuum (Center for Advanced
Research in Engineering, Pakistan) 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: Joe Macker (NRL), Alan Cullen (BAE
Systems), Song-Yean Cho (Samsung Software Center) and the entire IETF
MANET working group.
Clausen, et al. Expires December 21, 2006 [Page 37]
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Authors' Addresses
Thomas Heide Clausen
LIX, Ecole Polytechnique, France
Phone: +33 6 6058 9349
Email: T.Clausen@computer.org
URI: http://www.lix.polytechnique.fr/Labo/Thomas.Clausen/
Christopher M. Dearlove
BAE Systems Advanced Technology Centre
Phone: +44 1245 242194
Email: chris.dearlove@baesystems.com
URI: http://www.baesystems.com/ocs/sharedservices/atc/
Justin W. Dean
Naval Research Laboratory
Phone: +1 202 767 3397
Email: jdean@itd.nrl.navy.mil
URI: http://pf.itd.nrl.navy.mil/
The OLSRv2 Design Team
MANET Working Group
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Clausen, et al. Expires December 21, 2006 [Page 39]
