The Next Hop Resolution Protocol (NHRP) is an extension of the ATM ARP routing mechanism that is sometimes used to improve the efficiency of routing computer network traffic over Non-Broadcast, Multiple Access (NBMA) Networks. It is defined in IETF RFC 2332, and further described in RFC 2333. It can be used by a sender to determine a route with the fewest hops to a receiver. The protocol differs from ARP-type protocols in that it allows routing optimization across multiple IP subnets. NHRP is implemented by means of next-hop servers across IP subnets. The NHRP forms a part of the Multiprotocol Encapsulation over ATM (MPOA) protocol as described in RFC 2684. It also plays a role in Cisco's Dynamic Multipoint Virtual Private Network. A limitation of NHRP is its inability to improve multicast protocols.
From RFC 2332: "[NHRP] allows a source station (a host or router), wishing to communicate over [an NBMA] subnetwork, to determine the internetworking layer addresses and NBMA addresses of suitable 'NBMA next hops' toward a destination station."
- White, P.P. (April 1998). "ATM switching and IP routing integration: the next stage in Internet evolution?" (PDF). IEEE Communications Magazine. 36 (4): 79–83. doi:10.1109/35.667418. Retrieved 18 June 2016.
- "NHRP". Cisco. Retrieved 17 June 2016.
- B., Cole; J., Luciani; N., Doraswamy; D., Piscitello; D., Katz (April 1998). "NBMA Next Hop Resolution Protocol (NHRP)". tools.ietf.org. Retrieved 17 June 2016.
- Cansever, Derya H. (April 1998). "NHRP Protocol Applicability Statement". tools.ietf.org. Retrieved 17 June 2016.
- Rouse, Margaret. "What is Next Hop Resolution Protocol (NHRP)? - Definition from WhatIs.com". SearchNetworking. Retrieved 17 June 2016.
- Luciani, James V. (1 January 1997). Civanlar, Seyhan; Widjaja, Indra (eds.). "Next-hop resolution protocol". SPIE Proceedings. Broadband Networking Technologies. 3233: 161–165. Bibcode:1997SPIE.3233..161L. doi:10.1117/12.290456. S2CID 21461973.
- Ahmad, Khalid (2 April 2004). Sourcebook of ATM and IP Internetworking. John Wiley & Sons. p. 360. ISBN 9780471660941. Retrieved 18 June 2016.
- Dan, Grossman; Juha, Heinanen (September 1999). "Multiprotocol Encapsulation over ATM Adaptation Layer 5". tools.ietf.org.
- Newman, P.; Lyon, T.; Minshall, G. (1 March 1996). "Flow labelled IP: A connectionless approach to ATM". Proceedings of IEEE INFOCOM '96. Conference on Computer Communications. Vol. 3. pp. 1251–1260 vol.3. doi:10.1109/INFCOM.1996.493071. ISBN 0-8186-7293-5. S2CID 5482472. Retrieved 18 June 2016.