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Optimized Link State Routing Protocol (OLSR) (RFC3626)

IP.com Disclosure Number: IPCOM000019951D
Original Publication Date: 2003-Oct-01
Included in the Prior Art Database: 2003-Oct-14

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

T. Clausen: AUTHOR [+4]

Abstract

This document describes the Optimized Link State Routing (OLSR) protocol for mobile ad hoc networks. The protocol is an optimization of the classical link state algorithm tailored to the requirements of a mobile wireless LAN. The key concept used in the protocol is that of multipoint relays (MPRs). MPRs are selected nodes which forward broadcast messages during the flooding process. This technique substantially reduces the message overhead as compared to a classical flooding mechanism, where every node retransmits each message when it receives the first copy of the message. In OLSR, link state information is generated only by nodes elected as MPRs. Thus, a second optimization is achieved by minimizing the number of control messages flooded in the network. As a third optimization, an MPR node may chose to report only links between itself and its MPR selectors. Hence, as contrary to the classic link state algorithm, partial link state information is distributed in the network. This information is then used for route calculation. OLSR provides optimal routes (in terms of number of hops). The protocol is particularly suitable for large and dense networks as the technique of MPRs works well in this context.

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Network Working Group T. Clausen, Ed.

Request for Comments: 3626 P. Jacquet, Ed.

Category: Experimental Project Hipercom, INRIA

October 2003

Optimized Link State Routing Protocol (OLSR)

Status of this Memo

This memo defines an Experimental Protocol for the Internet

community. It does not specify an Internet standard of any kind.

Discussion and suggestions for improvement are requested.

Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2003). All Rights Reserved.

Abstract

This document describes the Optimized Link State Routing (OLSR)

protocol for mobile ad hoc networks. The protocol is an optimization

of the classical link state algorithm tailored to the requirements of

a mobile wireless LAN. The key concept used in the protocol is that

of multipoint relays (MPRs). MPRs are selected nodes which forward

broadcast messages during the flooding process. This technique

substantially reduces the message overhead as compared to a classical

flooding mechanism, where every node retransmits each message when it

receives the first copy of the message. In OLSR, link state

information is generated only by nodes elected as MPRs. Thus, a

second optimization is achieved by minimizing the number of control

messages flooded in the network. As a third optimization, an MPR

node may chose to report only links between itself and its MPR

selectors. Hence, as contrary to the classic link state algorithm,

partial link state information is distributed in the network. This

information is then used for route calculation. OLSR provides

optimal routes (in terms of number of hops). The protocol is

particularly suitable for large and dense networks as the technique

of MPRs works well in this context.

Clausen & Jacquet Experimental [Page 1]

RFC 3626 Optimized Link State Routing October 2003

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4

1.1. OLSR Terminology. . . . . . . . . . . . . . . . . . . . 5

1.2. Applicability. . . . . . . . . . . . . . . . . . . . . . 7

1.3. Protocol Overview . . . . . . . . . . . . . . . . . . . 8

1.4. Multipoint Relays . . . . . . . . . . . . . . . . . . . 9

2. Protocol Functioning . . . . . . . . . . . . . . . . . . . . 9

2.1. Core Functioning . . . . . . . . . . . . . . . . . . . 10

2.2. Auxiliary Functioning . . . . . . . . . . . . . . . . . 12

3. Packet Format and Forwarding . . . . . . . . . . . . . . . . 13

3.1. Protocol and Port Number. . . . . . . . . . . . . . . . 13

3.2. Main Address . . . . . . . . . . . . . . . . . . . . . 13

3.3. Packet Format . . . . . . . . . . . . . . . . . . . . . 14

3.3.1. Packet Header . . . . . . . . . . . . . . . . . . 14

3.3.2. Message Header . . . . . . . . . . . . . . . . . 15

3.4. Packet Processing and Message Flooding . . . . . . . . . 16

3.4.1. Default Forwarding Algorithm. . . . . . . . . . . 18

3.4.2. Considerations on Processing and Forwarding . . . 20

3.5. Message Emission and Jitter. . . . . . . . . . . . . . . 21

4. Info...