This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Note that other groups may also distribute working documents as Internet Drafts.
Internet Drafts are draft documents valid for a maximum of six months.
Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. 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 an ABR or out of the OSPF domain, is dropped. This document describes alternative ABR behaviors implemented in Cisco and IBM routers. Overview 1.1 Introduction An OSPF routing domain can be split into several subdomains, called areas, which limit the scope of LSA flooding.