NHRP for Destinations off the NBMA Subnetwork

Document Type Expired Internet-Draft (individual)
Authors Yakov Rekhter  , Joel Halpern 
Last updated 1998-06-26
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


The NBMA Next Hop Resolution Protocol (NHRP) [1] specifies a mechanism that allows a source station (e.g., a host or a router) on an NBMA subnetwork to find the NBMA subnetwork address address of a destination station when the destination station is connected to the NBMA subnetwork. For the case where the destination station is off the NBMA subnetwork the mechanism described in [1] allows to determine the NBMA subnetwork address of an egress router from the NBMA subnetwork that is ``nearest'' to the destination station. If used to locate an egress router wherein the destination station is directly behind the egress router, the currently document NHRP behaviors are sufficient. However, as documented elsewhere [2], there are cases where if used between routers for generalized transit, NHRP can produce loops. This document describes extensions to the NBMA Next Hop Resolution Protocol (NHRP) [1] that allow to acquire and maintain the information about the egress router without constraining the destination(s) to be directly connected to the egress router.


Yakov Rekhter (yakov@cisco.com)
Joel Halpern (jhalpern@newbridge.com)

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