NHRP Protocol Applicability Statement (RFC2333)
Original Publication Date: 1998-Apr-01
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
As required by the Routing Protocol Criteria [RFC 1264], this memo discusses the applicability of the Next Hop Resolution Protocol (NHRP) in routing of IP datagrams over Non-Broadcast Multiple Access (NBMA) networks, such as ATM, SMDS and X.25.
Network Working Group D. Cansever
Request for Comments: 2333 GTE Laboratories, Inc.
Category: Standards Track April 1998
NHRP Protocol Applicability Statement
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (1998). All Rights Reserved.
As required by the Routing Protocol Criteria [RFC 1264], this memo
discusses the applicability of the Next Hop Resolution Protocol
(NHRP) in routing of IP datagrams over Non-Broadcast Multiple Access
(NBMA) networks, such as ATM, SMDS and X.25.
1. Protocol Documents
The NHRP protocol description is defined in . The NHRP MIB
description is defined in .
This document summarizes the key features of NHRP and discusses the
environments for which the protocol is well suited. For the purposes
of description, NHRP can be considered a generalization of Classical
IP and ARP over ATM which is defined in  and of the Transmission
of IP Datagrams over the SMDS Service, defined in . This
generalization occurs in 2 distinct directions.
Firstly, NHRP avoids the need to go through extra hops of routers
when the Source and Destination belong to different Logical Internet
Subnets (LIS). Of course,  and  specify that when the source
and destination belong to different LISs, the source station must
forward data packets to a router that is a member of multiple LISs,
even though the source and destination stations may be on the same
logical NBMA network. If the source and destination stations belong
to the same logical NBMA network, NHRP provides the source station
with an inter-LIS address resolution mechanism at the end of which
both stations can exchange packets without having to use the services
of intermediate routers. This feature is also referred to as
"short-cut" routing. If the destination station is not part of the
logical NBMA network, NHRP provides the source with the NBMA address
of the current egress router towards the destination.
The second generalization is that NHRP is not specific to a
particular NBMA technology. Of course,  assumes an ATM network
and  assumes an SMDS network at their respective subnetwork
NHRP is specified for resolving the destination NBMA addresses of IP
datagrams over IP subnets within a large NBMA cloud. NHRP has been
designed to be extensible to network layer protocols other than IP,
possibly subject to other network layer protocol specific additions.
As an important application of NHRP, the...