COMMUNICATIONS/ICWS SEMINAR

"Ospf-mdr: an Extension of Ospf to Support      Mobile Ad Hoc Networks"

Richard Ogier, SRI International

July 29, 2008
3:30-4:30 pm
Room 141

Abstract

OSPF-MDR is a proposed extension of OSPFv3 to support MANETs, and is on track to become an Experimental RFC within the OSPF working group.  OSPF-MDR generalizes the Designated Router (DR) of OSPF by selecting a small subset of routers, called MANET Designated Routers (MDRs) that form a connected dominating set (CDS).  MDRs achieve scalability in MANETs similar to the way DRs achieve scalability in broadcast networks:

*       Initial flooding of link-state advertisments (LSAs) is performed only by MDRs, thus reducing overhead.
*       Backup MDRs perform backup flooding when MDRs fail, thus improving robustness.
*       Adjacencies (neighbors that maintain synchronized databases) are required to be formed only between MDRs and their neighbors, thus reducing overhead.

The CDS is constructed using 2-hop neighbor information provided by a modified Hello protocol.  The Hello protocol is optimized by allowing differential Hellos that report only changes in neighbor states.  OSPF-MDR also allows LSAs to provide either full or partial topology information, allowing overhead to be reduced by advertising less topology information.

This seminar gives an overview of OSPF-MDR and compares it to two other proposed MANET extensions of OSPF.  Simulation results are presented, showing that OSPF-MDR is the most scalable of the proposed extensions.



Short bio
Richard Ogier received a Ph.D. in Electrical Engineering in 1985 from the University of Illinois.  Since then, he has worked at SRI International in Menlo Park, CA, where he has worked on numerous projects involving network protocols. In the last 8 years, he has been involved with the IETF, where he designed the well-known MANET routing protocol TBRPF (RFC 3684) and OSPF-MDR (to become an RFC).