Internet DRAFT - draft-ahn-manet-multipath-dsr
draft-ahn-manet-multipath-dsr
MANET Working Group Sanghyun Ahn
Internet Draft University of Seoul
Expires: May 23, 2018 November 30, 2017
DSR Extensions for Multipath Routing
draft-ahn-manet-multipath-dsr-01.txt
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Abstract
This document describes how DSR [1] can be extended for the support
of MANET multipath routing. In DSR, the route record informatio is
available at the destination, so the destination can select multiple
routes with good characteristics and notify the source of them.
Therefore, in this draft, we describe how we can extend the Route
Request option to specify the number of routes selected at the
destination.
Table of Contents
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Extensions on DSR Options Header . . . . . . . . . . . . . . . 4
3.1 Extensions on DSR Route Request Option . . . . . . . . . . . . 4
4. Other Considerations . . . . . . . . . . . . . . . . . . . . . 5
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Requirements notation
The key words "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. Introduction
The mobile ad hoc network (MANET) is composed of a number of mobile
nodes which can communicate with each other through multiple wireless
links without the help of a wired infrastructure. Therefore,
in the MANET, the route connectivity tends to be very unstable.
This route unstability can be mitigated by providing more than
one route to a source and destination node pair. In recent years,
there have been intensive studies done on multipath routing protocols
for the MANET [2]. Also, multipath routing protocols may have the
advantage of providing load balancing by distributing data traffic
to a number of routes. On the other hand, it may incur more control
message overhead to set up multiple routes.
The DSR protocol [1] works based on the source routing mechanism
and supports multiple routes between a source and destination node
pair by maintaining several routes in the route cache
of the source node. That is, DSR basically support multipath routing
and the source routing capability makes the support of multipath
routing easier. However, in DSR, a route reply (RREP) message
with the information of a route is sent back to the source by an
intermediate node which has a fresh route to the destination or
by the destination itself. Hence, the source can collect a random
number of the routes to the destination.
In [3], the C flag is newly defined in the DSR Route Request option
in order to resolve the cached route reply implosion problem of DSR.
If the cached route reply capability is turned off (i.e., C = 0),
the destination can collect all the route information from the
source. So, it is possible for the destination to select those
routes with good characteristics, such as link-disjoint,
node-disjoint, etc. Therefore, in this draft, we extend the DSR
Route Request option to allow the source to specify the maximum
number of routes between the source and the destination, and
to make the destination to select the specified number of routes
from the obtained routes.
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3. Extensions on DSR Options Header
3.1 Extensions on DSR Route Request Option
The Route Request option in the DSR Options header is extended as
follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len | Identification |C|PC |R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Target Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address[1] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address[2] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address[n] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IP fields
The same as described in [1].
Route Request fields
The same as described in [3] except for the PC field and R bit.
PC (Path Count)
This field indicates the maximum number of routes between the
source and the destination. The default value of PC is 0 which
implies a single route between the source and the destination.
The source sets the PC value to the value which is one less than
the required maximum number of routes. For the cases of nonzero
PC values, the C bit has to be set to 0 (i.e., the cached route
reply capability is disabled). When the destination receives
an RREQ message with a nonzero PC value, it has to send back
at most (PC+1) different RREP messages (routes) to the source.
The mechanism to select those routes is out of the scope of
this draft.
R bit
Reserved bit.
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4. Other Considerations
TBD.
References
[1] D. Johnson, Y. Hu and D. Maltz, "The Dynamic Source Routing
Protocol," RFC 4728, February 2007.
[2] M. Tarique, K. E. Tepe, S. Abidi and S. Erfani, "Survey of
Multipath Routing Protocols for Mobile Ad Hoc Networks," Journal
of Network and Computer Applications, November 2009.
[3] S. Ahn, "DSR Extensions for the Resolution of Cached Route
Reply Implosion," IETF draft-ahn-manet-dsr-crri-02.txt,
November 2017.
Author's Address
Sanghyun Ahn
University of Seoul
90, Cheonnong-dong, Tongdaemun-gu
Seoul 130-743
Korea
Email: ahn@uos.ac.kr
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