OSPF ABR Behavior

Document Type Expired Internet-Draft (ospf WG)
Last updated 1999-02-26
Stream IETF
Intended RFC status (None)
Expired & archived
pdf htmlized (tools) htmlized bibtex
Stream WG state WG Document
Document shepherd No shepherd assigned
IESG IESG state Expired
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


OSPF [Ref1] is a link-state intra-domain routing protocol used for routing in IP networks. Though the definition of the ABR in the current OSPF specification does not require a router with multiple attached areas to have a backbone connection, it is actually necessary to provide successful routing to the inter-area and external destinations. If this requirement is not met all traffic, destined for the areas not connected to such ab ABR or out of the OSPF domain, is dropped. The rules of originating and processing Summary-LSAs given in the current OSPF standard [Ref1] can also result in suboptimal inter-area routing. Though all these problems can be fixed using virtual links, this memo describes an alternative implementation of the OSPF ABR behavior, which allows the administrator to avoid it or, if virtual links are still used, to decrease the number of configured virtual links. This memo also describes possible situations where the proposed implementation can be used.


Alex Zinin (azinin@cisco.com)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)