RFC 5614 MANET Extension of OSPF August 2009

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.