Mobile Ad Hoc Network (MANET) Extension of OSPF Using Connected Dominating Set (CDS) Flooding
RFC 5614

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Network Working Group                                           R. Ogier
Request for Comments: 5614                             SRI International
Category: Experimental                                       P. Spagnolo
                                                                  Boeing
                                                             August 2009

            Mobile Ad Hoc Network (MANET) Extension of OSPF
             Using Connected Dominating Set (CDS) Flooding

Abstract

   This document specifies an extension of OSPFv3 to support mobile ad
   hoc networks (MANETs).  The extension, called OSPF-MDR, is designed
   as a new OSPF interface type for MANETs.  OSPF-MDR is based on the
   selection of a subset of MANET routers, consisting of MANET
   Designated Routers (MDRs) and Backup MDRs.  The MDRs form a connected
   dominating set (CDS), and the MDRs and Backup MDRs together form a
   biconnected CDS for robustness.  This CDS is exploited in two ways.
   First, to reduce flooding overhead, an optimized flooding procedure
   is used in which only (Backup) MDRs flood new link state
   advertisements (LSAs) back out the receiving interface; reliable
   flooding is ensured by retransmitting LSAs along adjacencies.
   Second, adjacencies are formed only between (Backup) MDRs and a
   subset of their neighbors, allowing for much better scaling in dense
   networks.  The CDS is constructed using 2-hop neighbor information
   provided in a Hello protocol extension.  The Hello protocol is
   further optimized by allowing differential Hellos that report only
   changes in neighbor states.  Options are specified for originating
   router-LSAs that provide full or partial topology information,
   allowing overhead to be reduced by advertising less topology
   information.

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.

Ogier & Spagnolo              Experimental                      [Page 1]
RFC 5614                MANET Extension of OSPF              August 2009

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Table of Contents

   1. Introduction ....................................................4
      1.1. Terminology ................................................5
   2. Overview ........................................................7
      2.1. Selection of MDRs, BMDRs, Parents, and Adjacencies .........8
      2.2. Flooding Procedure .........................................9
      2.3. Link State Acknowledgments ................................10
      2.4. Routable Neighbors ........................................10
      2.5. Partial and Full Topology LSAs ............................11
      2.6. Hello Protocol ............................................12
   3. Interface and Neighbor Data Structures .........................12
      3.1. Changes to Interface Data Structure .......................12
      3.2. New Configurable Interface Parameters .....................13
      3.3. Changes to Neighbor Data Structure ........................15
   4. Hello Protocol .................................................17
      4.1. Sending Hello Packets .....................................17
      4.2. Receiving Hello Packets ...................................20
      4.3. Neighbor Acceptance Condition .............................24
   5. MDR Selection Algorithm ........................................25
      5.1. Phase 1: Creating the Neighbor Connectivity Matrix ........27
      5.2. Phase 2: MDR Selection ....................................27
      5.3. Phase 3: Backup MDR Selection .............................29
      5.4. Phase 4: Parent Selection .................................29