MANET Autoconfiguration (AUTOCONF) I. Chakeres
Internet-Draft Motorola
Intended status: Informational J. Macker
Expires: December 21, 2007 Naval Research Laboratory
T. Clausen
LIX, Ecole Polytechnique
June 19, 2007
Mobile Ad hoc Network Architecture
draft-ietf-autoconf-manetarch-03
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Abstract
This document discusses Mobile Ad hoc NETworks (MANETs). It
introduces basic MANET terms, characteristics, and challenges. This
document also defines several MANET entities and architectural
concepts.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Borrowed Terminology . . . . . . . . . . . . . . . . . . . 3
2.2. MANET Terminology . . . . . . . . . . . . . . . . . . . . 5
3. MANET Motivation Discussion . . . . . . . . . . . . . . . . . 6
4. MANET Interface Characteristics . . . . . . . . . . . . . . . 7
4.1. Qualities - Wireless, Mobile, Ad hoc . . . . . . . . . . . 7
4.2. Challenges . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2.1. Semi-Broadcast Interface . . . . . . . . . . . . . . . 8
4.2.2. Fuzzy Relationships Between Nearby MANET Routers &
MANET Routers Extended Neighborhood . . . . . . . . . 9
4.2.3. MANET Membership . . . . . . . . . . . . . . . . . . . 9
5. Addressing & the MANET Prefix Model . . . . . . . . . . . . . 10
5.1. General Address Architecture . . . . . . . . . . . . . . . 11
5.2. MANET Interface Configuration . . . . . . . . . . . . . . 12
5.3. Routers and Hosts in a MANET . . . . . . . . . . . . . . . 13
6. MANETs' Place in the Network Stack . . . . . . . . . . . . . . 14
7. Cross Layering . . . . . . . . . . . . . . . . . . . . . . . . 15
8. Deployment Taxonomy . . . . . . . . . . . . . . . . . . . . . 15
8.1. Service Availability . . . . . . . . . . . . . . . . . . . 15
8.2. Number of MANET Routers in a MANET . . . . . . . . . . . . 16
8.3. Example Deployments . . . . . . . . . . . . . . . . . . . 17
9. Security Considerations . . . . . . . . . . . . . . . . . . . 17
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
12. Informative References . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
Intellectual Property and Copyright Statements . . . . . . . . . . 21
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1. Introduction
A Mobile Ad hoc NETwork (MANET) consists of a loosely connected set
of MANET routers. Each MANET router embodies routing/forwarding
functionality and may also incorporate host functionality. These
routers organize and maintain a routing structure among themselves.
These routers may communicate over wireless links with asymmetric
reachability, may be mobile, and may join and leave the network at
any time. MANETs' characteristics create challenges in several
areas, and may require protocol extensions or new MANET protocols
altogether.
This document is focused on IP networking, though many of MANETs'
concepts and issues span the protocol stack.
This document is meant to complement [RFC2501] in describing and
defining MANET.
2. Terminology
Much of the terminology in this document was borrowed from existing
documents, to list a few [RFC1812], [RFC2328], [RFC2453], [RFC2460],
[RFC2461], [RFC3513], [RFC3753], [I-D.iab-multilink-subnet-issues],
[I-D.templin-autoconf-dhcp], and [I-D.ietf-ipv6-2461bis]. Note that
the original text for the terms is often modified, though we have
attempted to maintain the same meaning.
2.1. Borrowed Terminology
This document employs the following definitions:
Node (N)
any device (router or host) that implements IP.
Router (R)
a node that forwards IP packets not explicitly addressed to
itself.
Host (H)
any node that is not a router, i.e. a host does not forward
packets addressed to others.
Link
A communications facility at a layer below IP, over which nodes
exchange IP packets directly without decrementing IP TTL (Hop
Limit).
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Asymmetric Reachability
A link where non-reflexive and/or non-transitive reachability is
part of normal operation. Non-reflexive reachability means that
packets from X reach Y but packets from Y don't reach X. Non-
transitive reachability means packets from X reach Y, and packets
from Y reach Z, but packets from X don't reach Z. Many radio/
wireless interfaces exhibit these properties.
Neighbor
If node X can directly exchange IP packets with node Y, then node
Y is node X's neighbor.
Interface
A node's point of attachment to a communication link.
Broadcast Interface
An interface supporting many attached nodes, together with the
capability to address a single link layer transmission to all of
the attached nodes (broadcast). The set of nodes receiving a
given physical broadcast message are the neighbors of the node
originating the message.
Full-Broadcast Interface (FBI)
A broadcast interface which does not exhibit asymmetric
reachability. All nodes on the interface can send and receive IP
packets directly, all nodes are symmetric neighbors. An Ethernet
segment is an example of a FBI.
Semi-Broadcast Interface (SBI)
A broadcast interface that may exhibit asymmetric reachability. A
FBI is a special case of SBI. Multiple access wireless radio
interfaces are often SBI.
Site
a set of one or more links.
Flooding
The process of forwarding or distributing information to all
devices with in a bounded region.
Border Router (BR)
a router that participates in multiple routing regions, and often
multiple routing protocols. A BR defines the border between its
multiple routing regions. A BR is responsible for presenting a
consistent picture of the nodes reachable through itself to each
routing region. A BR determines the routing information to
propagate between different routing regions.
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2.2. MANET Terminology
We define the following MANET entity:
MANET Router (MNR)
a MANET router embodies router functionality and may also
incorporate an internally addressable host (IAH) logic, as
illustrated in Figure 1. A MANET router has one or more
interfaces. To simplify discussion we will classify the
interfaces into two categories: classic IP interfaces & MANET
interfaces. MANET interfaces are defined as interfaces that
demonstrate asymmetric reachability and/or neighboring nodes with
addresses that are not known a priori. A MANET router may also
have zero or more classic IP interfaces to which other nodes may
connect; i.e. the router may be responsible for several IP
prefixes. A MANET router may participate in routing on zero or
more MANET interfaces. A MANET router may participate in routing
on zero or more classic IP interfaces.
<~~~~~~+~~~~~~> Routing-MANET
| Interface(s)
''''''''''|'''''''''''''''''
' +-------|--------------+ '
' | Router Functionality |...................
' +-------+-+------------+ ' Routing-Classic
' : : ' IP Interface(s)
' MANET : +-----------+ '
' Router : | Internal | '
' : |Addressable| '
' : |Host Logic | '
' : | (IAH) | '
' : +-----------+ '
'''''''''':'''''''''''''''''
: Nodes that live behind the router
+......+.........+ ============
: : = : =
+-+-+ +----+----+ =CLASSIC IP=
| N | * * * | Node(s) | =INTERFACES=
+---+ +---------+ ============
Figure 1: MANET Router
In MANETs there are several architectural scopes. We define the
following scopes:
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MANET Neighbors
a set of MANET routers that is reachable via one IP hop, reachable
via link-local [RFC4007] messaging.
MANET N-Neighborhood
a set of MANET routers that is reachable via N-hops. These
routers usually have a large number of common neighboring MANET
routers and may directly compete for the same shared wireless
resources.
MANET
a routing region consisting of a set of MANET routers that is
reachable via one or more MANET router hops. If a MANET connects
to other routing regions, its border is defined by Border Routers.
If a link forms between two previously separated MANET routers or
MANETs, the two MANETs will merge to form a single larger MANET.
Similarly, if a critical link between two MANET routers is lost, then
the MANET will be partitioned into two now separate MANETs.
When discussing MANETs' connectivity to other networks, such as the
Internet, a MANET is bounded by border routers (BR). That is, a
MANETs' BR form a border between a MANET and other routing regions.
3. MANET Motivation Discussion
The Internet Protocol (IP) core design tenets -- connectionless
networking and packet-based forwarding -- are ideally suited for use
in highly dynamic contexts, such as MANETs. Yet, some additional
functionality is required to meet the unique challenges and
opportunities present in MANETs.
The initial motivation for MANETs was called Packet Radio (PR)
networking [FL01]. In PR, each router is equipped with a single SBI.
This configuration is the simplest MANET router configuration. Each
router may be mobile, and the routers may be or may become spatially
distributed such that all routers cannot communicate directly. That
is, two routers might require one or more intermediate routers to
forward (route) packets on their behalf. In the example shown in
Figure 2: for R1 to send packets to R3, the intermediary R2 must
relay the packets. This implies that R2 must receive the packet from
R1 on its interface and determine that it must retransmit the packet
over the same interface as the one where the packet was received, in
order for the packet to reach R3. This example also illustrates how
SBIs differ from FBIs: from the point of view of R2, both R1 and R3
are neighboring routers, whereas R1 and R3 are not themselves
neighboring routers of one another.
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Communication
Range
<~~~~~~+~~~~~~> <~~~~~~+~~~~~~>
Single | <~~~~~~+~~~~~~> |
SBI +-|-+ +-|-+ +-|-+
| R1| | R2| | R3|
+---+ +---+ +---+
Figure 2: Basic MANET Network
In addition to nodes' asymmetric reachability other challenges exist.
In PR networks, shared wireless resources result in interdependence
between nearby nodes, and these nodes often communicate directly or
indirectly. The dynamic wireless interface characteristics and node
mobility often manifest as frequent network topology changes.
PR networks also lead to several other architecture related
challenges. One challenge was to attach these PR networks to other
networks, especially fixed networks like the ARPANET. Another
related challenge was how to deal with the large disparity between
different node and interface characteristics.
These PR network challenges helped stimulate the Internet Protocol;
an architecture based on connectionless networking and packet-based
forwarding that enables interconnection of heterogeneous devices over
heterogeneous interfaces.
4. MANET Interface Characteristics
Inheriting from Packet Radio as described above, chief
particularities of MANETs are the characteristics and qualities of
MANET interfaces, and the challenges these entail for protocol design
and development.
4.1. Qualities - Wireless, Mobile, Ad hoc
In MANET several qualities impact protocol design. The most
fundamental qualities are wireless interface characteristics,
mobility, and ad hoc interaction.
Wireless interfaces exhibit challenging characteristics when compared
to wired interfaces. Many protocols (e.g. IPv6 neighbor discovery
[RFC2461]) do not operate in wireless networks with asymmetric
reachability. Wireless interfaces also exhibit time varying
performance that can significantly impact local communication.
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Mobility can also exacerbates wireless networking issues, making it
more challenging to attain, establish, and maintain network
relationships between nodes.
Ad hoc networking further compounds problems by allowing nodes to
join and leave the network, or even form new networks, at will.
4.2. Challenges
MANETs characteristics result in many challenges. These challenges
reveal themselves in many forms, and MANET specific protocols must
often be developed.
4.2.1. Semi-Broadcast Interface
Given a wireless SBI (with non-transitive and non-reflexive
properties) and spatially distributed nodes, each node may have a
different unique partial view of the MANET. That is, each node may
have a different set of adjacent nodes.
Communication
Range
<~~~~~~+~~~~~~> <~~~~~~+~~~~~~>
Single | <~~~~~~+~~~~~~> |
SBI +-|-+ +-|-+ +-|-+
| R1| | R2| | R3|
+---+ +---+ +---+
R1 R2 R3
-------------------------
Neighboring R2 R1 R2
Routers R3
Figure 3: Semi-Broadcast Interface (SBI) Neighboring Routers
The possibly unique set of adjacent nodes in each node often requires
nodes to forward packets out the same wireless interface as the one
over which they were received. Topologically, this act of forwarding
out the same interface causes a packet to reach a possibly different
set of nodes by traversing the wireless communication medium in a new
location. An example is provided in Figure 3, where each router is
capable of reaching a different set of routers.
The act of forwarding packets out of the same interface as the one
over which they were received often results in duplicate IP packets
being received at routers with more than one neighboring router,
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while also reaching a new subset of nodes.
4.2.2. Fuzzy Relationships Between Nearby MANET Routers & MANET Routers
Extended Neighborhood
Defining the process of determining neighboring MANET routers'
existence, continued existence, and loss of existence is a
fundamental challenge in MANETs. Relationships with neighboring
MANET routers are hard to define due to the expected interface
characteristics: non-transitive, non-reflexive, time varying, and
other wireless properties.
Historically, two nodes are either neighbors or not neighbors and
several simple mechanisms have been used to determine a neighbor
relationship: single packet reception, acceptable loss rates, and
simple handshakes. In wireless networks the types of neighbor
relationships expand, as do the mechanisms to detect and maintain the
state of such relationships.
In wireless networks, nodes may often have non-reflexive (also often
seen called unidirectional) communication links. Wireless networks
also experience significant time varying packet delivery, so simple
loss rates may not be sufficient to define a neighbor relationship.
Similarly, as nodes move relatively to each other, past loss rates
may not reflect future communication capabilities.
In wireless systems, nodes within the same small geographic region
are often densely connected with other nearby nodes. These nodes
form a set of extended neighbor relationships that is referred to as
a neighborhood. A neighborhood is typically composed of several
nodes, with each node being densely connected to other nodes.
These more dynamic neighbor relationships do not sit well with
certain Internet Protocols designed assuming an fixed Ethernet like
model to communication links (reflexive, transitive, and stable).
Given the fuzzy neighbor relationships between MANET routers, the
addressing model often associated with a Ethernet link is not valid.
For example, in an Ethernet network routers are often told that a
particular range of addresses are directly reachable. In MANETs' a
node often cannot make assumptions that a particular set of
addressable nodes is always reachable. Instead, nodes must detect
and determine neighboring devices, and handle changes to this set
over time.
4.2.3. MANET Membership
Given MANETs' characteristics (mobile, wireless, ad hoc), determining
a MANETs' membership is difficult, if not impossible in certain
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scenarios.
/----------------------\ /----------------------\
| MANET | | MANET |
| +----+ +----+ +----+ | | +----+ +----+ +----+ |
| |MNR1+-+MNR2+-+MNR3| | | |MNR1+-+MNR2+-+MNR3| |
| +-+--+ +----+ +----+ | | +----+ +----+ +-+--+ |
| | | | | |
| +-+--+ | Change | +-+--+ |
| |MNR4| | in | |MNR7| |
| +----+ | Time | +----+ |
| \ | \----------------------/
| +----+ |
| |MNR5| |
| +----+ | /----------------------\
| / \ | | MANET |
| +----+ +----+ | | +----+ +----+ +----+ |
| |MNR6| |MNR7| | | |MNR6+-+MNR4+-+MNR5| |
| +----+ +----+ | | +----+ +----+ +----+ |
\----------------------/ \----------------------/
Figure 4: MANET(s)
At one moment a MANET might consist of a certain set of nodes, and
the next the MANET could partition into several MANETs. Later it
might re-merge or merge with a new set of nodes and form a larger
MANET.
Certain routers in a MANET might connect to other routing regions.
These routers are called Border Routers (BR), and they often run
multiple routing protocol instances. The BR are responsible for
choosing the routing information to share between the various
attached routing regions. The BR should also present a consistent
picture of the nodes reachable through them.
As MANET membership changes, so does the connectivity of BR within
the MANET. Therefore, a BR may be challenged to present a consistent
set of reachable nodes. It may even choose not to share routing
information about the MANET topology to other routing regions.
5. Addressing & the MANET Prefix Model
This section presents an architectural model for MANETs which
preserves the integrity of the IP addressing architecture while
allowing for the particularities of MANETs.
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5.1. General Address Architecture
This architectural model considers MANET routers as simply routers
with nodes attached, as illustrated in Figure 5. The attached nodes
may be "external" (i.e. attached to the router via other network
interfaces) or an internal addressable host logic (IAH) - however the
important observation to make is, that the links between these
entities and the router are classic IP links. This fact implies
that, from the point of view of these entities and the applications
running on them, connectivity is via a classic IP link. Therefore
applications are not exposed to the specific characteristics of
interfaces with asymmetric reachability or unknown address
membership. Hosts are connected to the MANET via a MANET router,
which has one or more interfaces participating in MANET routing.
<~~~~~~+~~~~~~> MANET <~~~~~~+~~~~~~>
| Interfaces |
''''''''''|'''''''''' ''''''''''|''''''''''
'MANET +-|-+ ' ' +-|-+ MANET '
'Router | R ................................ R | Router'
' +-+-+ ' ' +-+-+ '
' : : ' ' : : '
' : +---+ ' ' : +---+ '
' : |IAH| ' ============ ' : |IAH| '
' : +---+ ' = : = ' : +---+ '
'''''''''':'''''''''' =Classic IP= '''''''''':''''''''''
+......+......+ =Interfaces= +......+......+
: : ============ : :
+-+-+ +-+-+ +-+-+ +-+-+
| N | * * * | N | | N | * * * | N |
+---+ +---+ +---+ +---+'
Figure 5: MANET Addressing Model
A MANET router can be delegated zero or more prefixes. If a MANET
router is delegated a prefix p::, then prefixes derived from this
prefix (p:1::, p:2::, ...) may be assigned to the MANET routers
interfaces towards classic IP link(s), and nodes on these classic IP
links may be assigned addresses from within this prefix, and
configured with this prefix according to the address
autoconfiguration mechanisms governing these links [RFC2461] and
[RFC2462]. This concept is illustrated in Figure 6.
Interface(s) with asymmetric reachability or unknown/indeterministic
membership attached to the router are specifically *NOT* configured
with this prefix. The configuration of these MANET interfaces are
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detailed in Section 5.2.
If a MANET router via one of its interfaces is connected to a classic
IP link, on which an existing prefix and address allocation entity is
present, then this interface towards that classic IP link may be
configured with addresses and prefixes from that classic IP link.
This information may be in addition to or instead of configuring the
MANET routers interface towards that classic IP link with a prefix
derived from the prefix delegated to the MANET router. A MANET
routing protocol running on the MANET routers' MANET interface(s) may
or may not include addresses and prefixes acquired on that MANET
routers' interfaces towards classic IP links in its routing messages.
The routing protocol configuration is administratively determined
when deploying a MANET.
MANET <~~~~~~+~~~~~~> Example
Interface | Assigned
''''''''''|'''''''''' Prefix
' MANET +-|-+ ' =========
' Router| R | ' <=== P:: =
' +-+-+ ' =========
' : : '
' : +---+ ' =========
============ ' : |IAH| ' <=== P:1:: =
= : = ' : +---+ ' =========
=Classic IP= '''''''''':''''''''''
=Interfaces= :
============ : =========
+......+......+ <=== P:2:: =
: : =========
+-+-+ +-+-+
| N | * * * | N |
+---+ +---+
P:2::1 P:2::N
Figure 6: MANET Router and Prefixes
5.2. MANET Interface Configuration
MANET specific behaviors are exclusively exposed to the MANET
interface(s) of the routers. This behaviors may include asymmetric
reachability, semi-broadcast interfaces, fuzzy MANET router neighbor
relationships, unknown/indeterministic MANET membership, rapid
topology dynamics, etc.
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The following characteristics deserve particular mention, since they
distinguish these MANET interface(s) and the MANET link model from
the classic IP link model:
Unique Prefixes
MANET interfaces must be configured with unique prefixes. The
reason for this requirements is so that no two MANET interfaces
are configured to appear within the same IP prefix, since node
membership cannot be ensured. Some common ways to achieve this
are:
* unnumbered interfaces (IPv4) [RFC1812];
* link-local addresses (IPv6);
* /128 (IPv6) or /32 (IPv4) prefixes.
It is worth noting that prefix lengths shorter than /128 (IPv6) or
/32 (IPv4) are possible on the MANET interfaces, as long as the
prefixes are unique to a single MANET interface. Note that the
above statement is not an exception, but simply a clarification
that MANET are no different from other networks in this respect.
Link-local Multicast/Broadcast Scope
On a MANET interface, a packet sent to a link-local multicast or
broadcast addresses reaches the interfaces of neighboring MANET
routers, regardless of their configured addresses. Link-local
packets are never forwarded and since a MANET may span several
hops, nodes cannot assume that a packet sent to a link-local
address will reach all MANET routers within a MANET.
5.3. Routers and Hosts in a MANET
The MANET addressing model presented in this section makes a clear
separation between the role of router and host in a MANET,
recognizing that:
o MANET interfaces are seen only by the MANET aware router, assumed
to be MANET aware, and running appropriate protocols;
o nodes and subnets on non-MANET interface(s) assume a classic IP
link model;
o applications on hosts and protocols assuming classic IP interfaces
run unmodified.
MANET protocols are protocols which are developed to work on MANET
interfaces and to be MANET-aware. The MANET WG is chartered to
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develop routing protocols for MANET interfaces. The Autoconf WG is
chartered to develop autoconfiguration protocols for MANET interfaces
and MANET routers.
Note that this addressing framework is similar to how routing in the
existing Internet is structured. Routers run their routing protocol
over router interconnects with various characteristics to which only
the routing protocols are privy. On the other hand, hosts connect to
the routers over classic IP interfaces with well-known
characteristics.
6. MANETs' Place in the Network Stack
While the MANET WG is focused on network (L3) routing, that does not
imply that MANETs and their protocols are limited to L3. Several
previous and existing efforts are applying MANET protocols at various
layers. The challenges discussed above, exist independent of at
which layer MANET protocols are deployed. Of course, the protocols
themselves may need to be retooled slightly to accommodate the
information available to the deployed layer.
MANET MAC layer (L2) routing, more often called bridging, may work in
homogeneous wireless networks for delivering frames over multiple
hops. One example of L2 MANET is being developed in the IEEE 802.11s
effort.
L2 routing/bridging hides the multiple L2 hops from L3. This
behavior can be advantageous as this network can transparently mimic
an Ethernet, to some extent. The ability to mimic Ethernet allows
the L2 MANET to utilize existing L3 network protocols. On the other
hand, this transparency may lead to performance problems. For
example, if the L3 protocols make heavy use of broadcast messaging or
if devices assume that high-speed wired bandwidth resources are
available.
L2 MANET does not enable heterogeneity. That is, L2 MANET is not
capable of bridging across heterogeneous interfaces. For example, L2
bridging cannot directly bridge two L2 technologies with different
addressing schemes. It can also be difficult if the frame sizes of
two L2 vary, as this could require breaking a single frame into
multiple frames of a different format.
L3 MANET enables heterogeneous networking, as IP was built with this
feature in mind. Forming a MANET at L3 implies that the L3 protocols
must handle the challenges presented in this document.
MANET like protocols can also be used at higher layers. One example
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is peer-to-peer (P2P) networks. These networks have some of the same
challenges as MANET, e.g. variable neighbor relationships and
changing membership.
7. Cross Layering
In wireless networks, and especially in MANET, extended interfacing
among the network layers (physical, MAC, link, network, etc.) can be
extremely useful. Arguably, for MANET deployments to be successful,
some degree of cross layering should be considered. For example,
link layer feedback that a packet/frame was not able to be sent or
that it was not received could be used by the network layer to
indicate that a neighboring MANET router is no longer reachable.
This information and other extended interfacing could reduce, or
eliminate, some upper layer messaging. Further, it could
significantly reduce the latency in decision making. Note that
though a certain lower layer information is valuable, it likely needs
to be extrapolated or filtered before accurate assumptions about the
network state can be made. For example, failure to deliver a single
frame by itself may not be a good indicator that a node is or is not
reachable.
In networks with several different layers of MANET mechanism, the
sharing of information across different layers can be even more vital
to creating and maintaining the network. For example, if a P2P
network is run on top of a L3 MANET, the two networks can share
information to use a similar optimized topology, and neighboring
MANET router state changes to reduce the messaging or the latency in
making decisions.
8. Deployment Taxonomy
The present and future proliferation of inexpensive wireless
interfaces continues to stimulate technical interest and developments
in the area of MANET for a wide variety of deployment scenarios. In
this section, we present several characteristics for describing
expected MANET deployments.
8.1. Service Availability
Nodes often expect certain services/servers to be available. When
describing a deployment scenario, it is important to specify the
expected services available and the distance between the
participating devices. In MANET, nodes might assume a service is
available locally (within one IP hop) or within a particular scope
(one or more IP hops - MANET, site, global). Nodes might assume in
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certain deployments that no special servers/services are available.
Finally, nodes might assume that servers are sometimes available, but
their availability is not guaranteed or ensured.
Different frameworks for autoconfiguration, network management, and
intra-AS routing can be developed based upon the expected constraints
and operating conditions.
8.2. Number of MANET Routers in a MANET
The number of peer MANET routers in a MANET is an important
consideration. This number is not the complete number of nodes in a
MANET (since MANET routers may support an arbitrary number of
connected nodes) but a measure of the number of MANET routers
participating as a cohesive flat routing region. That is, the number
of MANET routers within a single routing region.
While the number of peer MANET routers does not define scalability of
a MANET protocol, it is often useful to discuss the number of peer
MANET router to get a feel for maturity of typical deployment
solutions. For simplicity we define the following network sizes to
aid in discussion:
Small
2-30 peer MANET routers
Moderate
30-100 peer MANET routers
Large
100-1000 peer MANET routers
Very large
Larger than 1000 peer MANET routers
At the time of writing, small and moderate size peer MANET routing
scenarios have matured and have reasonable testing and deployment
experience. These sizes can perform reasonably well in many cases
without hierarchy. MANET architectures can, of course, support
routing hierarchies to improve scaling. Large and very large MANET
routing regions that are flat are still a topic of active research
and are not considered here. One can apply hierarchy to achieve
scaling, but again that is not being discussed here. Existing MANET
routing developments, such as SMF [I-D.ietf-manet-smf], have shown
significant performance improvements and capabilities even in small
peer router size deployments and experiments using classical routing
designs.
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8.3. Example Deployments
Here we provide a short list of example deployment scenarios:
Home, office, campus, and community mesh networks
Disaster relief and first responder networks
Sensor networks
Range extension
Military communications
Automotive networks
9. Security Considerations
TBD
10. IANA Considerations
This is an informational document. IANA requirements for MANET
related protocols will be developed within the protocol
specifications for MANET protocols.
11. Acknowledgments
Discussions and developments concepts and architectural issues have
evolved over many years of discussion of related work within the
MANET WG. There are obviously many people that have contributed to
past discussions and related draft documents within the WG that have
influenced the development of these concepts that deserve
acknowledgment. The authors would like to thank all contributors to
the MANET and AUTOCONF WG efforts and those that have helped in the
review and content process.
While not entirely complete the authors would like to in
particular thank the following individuals for there discussions
and contributions:
Jari Akko
Emmanuel Baccelli
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Alan Cullen
Justin Dean
Christopher Dearlove
Tom Henderson
Bob Hinden
Thomas Narten
Charles Perkins
Subhranshu Singh
Fred Templin
Dave Thaler
Seung Yi
12. Informative References
[DWN03] Macker, J. and S. Corson, "Mobile Ad hoc Networking:
Routing Technology for Dynamic, Wireless Networks", IEEE
Press, Mobile Ad hoc Networking, Chapter 9, 2003.
[FL01] Freebersyser, J. and B. Leiner, "A DoD perspective on
mobile ad hoc networks", Addison Wesley C. E. Perkin, Ed.,
2001, pp. 29--51, July 2001.
[I-D.iab-multilink-subnet-issues]
Thaler, D., "Multilink Subnet Issues",
draft-iab-multilink-subnet-issues-03 (work in progress),
January 2007.
[I-D.ietf-ipv6-2461bis]
Narten, T., "Neighbor Discovery for IP version 6 (IPv6)",
draft-ietf-ipv6-2461bis-11 (work in progress), March 2007.
[I-D.ietf-manet-smf]
Macker, J., "Simplified Multicast Forwarding for MANET",
draft-ietf-manet-smf-04 (work in progress), March 2007.
[I-D.templin-autoconf-dhcp]
Templin, F., "MANET Autoconfiguration",
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Internet-Draft MANET Architecture June 2007
draft-templin-autoconf-dhcp-07 (work in progress),
March 2007.
[RFC1812] Baker, F., "Requirements for IP Version 4 Routers",
RFC 1812, June 1995.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC2453] Malkin, G., "RIP Version 2", STD 56, RFC 2453,
November 1998.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461,
December 1998.
[RFC2462] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.
[RFC2501] Corson, M. and J. Macker, "Mobile Ad hoc Networking
(MANET): Routing Protocol Performance Issues and
Evaluation Considerations", RFC 2501, January 1999.
[RFC3513] Hinden, R. and S. Deering, "Internet Protocol Version 6
(IPv6) Addressing Architecture", RFC 3513, April 2003.
[RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology",
RFC 3753, June 2004.
[RFC4007] Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and
B. Zill, "IPv6 Scoped Address Architecture", RFC 4007,
March 2005.
Authors' Addresses
Ian D Chakeres
Motorola
Bagmane Tech Park
66/1, Plot 5, CV Raman Nagar
Bangalore, Karnataka 560093
India
Email: ian.chakeres@gmail.com
URI: http://www.ianchak.com/
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Joe Macker
Naval Research Laboratory
Washington, DC 20375
USA
Email: macker@itd.nrl.navy.mil
Thomas Heide Clausen
LIX, Ecole Polytechnique
91128 Palaiseau CEDEX
France
Email: T.Clausen@computer.org
URI: http://www.thomasclausen.org/
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