Next Hop Resolution Protocol

Last updated

The Next Hop Resolution Protocol (NHRP) is an extension of the ATM ARP routing mechanism [1] that is sometimes used to improve the efficiency of routing computer network traffic over a non-broadcast, multiple access (NBMA) network. [2] It is defined in IETF RFC 2332, [3] and further described in RFC 2333. [4] It can be used by a sender to determine a route with the fewest hops to a receiver. [5] The protocol differs from ARP-type protocols in that it allows routing optimization across multiple IP subnets. [6] NHRP is implemented by means of next-hop servers across IP subnets. [7]

Contents

NHRP forms a part of the Multiprotocol Encapsulation over ATM (MPOA) protocol as described in RFC 2684. [8] [9] It also plays a role in Cisco's Dynamic Multipoint Virtual Private Network. [2] A limitation of NHRP is its inability to improve[ clarify ] multicast protocols. [1]

Description

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."

Related Research Articles

<span class="mw-page-title-main">Internet Protocol version 4</span> Fourth version of the Internet Protocol

Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version deployed for production on SATNET in 1982 and on the ARPANET in January 1983. It is still used to route most Internet traffic today, even with the ongoing deployment of Internet Protocol version 6 (IPv6), its successor.

<span class="mw-page-title-main">IPv6</span> Version 6 of the Internet Protocol

Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion, and was intended to replace IPv4. In December 1998, IPv6 became a Draft Standard for the IETF, which subsequently ratified it as an Internet Standard on 14 July 2017.

The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP). Early versions of this networking model were known as the Department of Defense (DoD) model because the research and development were funded by the United States Department of Defense through DARPA.

Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses. Whereas network addresses identify endpoints the labels identify established paths between endpoints. MPLS can encapsulate packets of various network protocols, hence the multiprotocol component of the name. MPLS supports a range of access technologies, including T1/E1, ATM, Frame Relay, and DSL.

In computer networking, Point-to-Point Protocol (PPP) is a data link layer communication protocol between two routers directly without any host or any other networking in between. It can provide loop detection authentication, transmission encryption, and data compression.

Open Shortest Path First (OSPF) is a routing protocol for Internet Protocol (IP) networks. It uses a link state routing (LSR) algorithm and falls into the group of interior gateway protocols (IGPs), operating within a single autonomous system (AS).

The Routing Information Protocol (RIP) is one of the oldest distance-vector routing protocols which employs the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from source to destination. The largest number of hops allowed for RIP is 15, which limits the size of networks that RIP can support.

The Address Resolution Protocol (ARP) is a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address. This mapping is a critical function in the Internet protocol suite. ARP was defined in 1982 by RFC 826, which is Internet Standard STD 37.

A virtual private network (VPN) is a mechanism for creating a secure connection between a computing device and a computer network, or between two networks, using an insecure communication medium such as the public Internet.

<span class="mw-page-title-main">Subnet</span> Logical subdivision of an IP network

A subnetwork or subnet is a logical subdivision of an IP network. The practice of dividing a network into two or more networks is called subnetting.

The Point-to-Point Protocol over Ethernet (PPPoE) is a network protocol for encapsulating Point-to-Point Protocol (PPP) frames inside Ethernet frames. It appeared in 1999, in the context of the boom of DSL as the solution for tunneling packets over the DSL connection to the ISP's IP network, and from there to the rest of the Internet. A 2005 networking book noted that "Most DSL providers use PPPoE, which provides authentication, encryption, and compression." Typical use of PPPoE involves leveraging the PPP facilities for authenticating the user with a username and password, predominately via the PAP protocol and less often via CHAP. Around 2000, PPPoE was also starting to become a replacement method for talking to a modem connected to a computer or router over an Ethernet LAN displacing the older method, which had been USB. This use-case, connecting routers to modems over Ethernet is still extremely common today.

In computer networking and telecommunications, a pseudowire is an emulation of a point-to-point connection over a packet-switched network (PSN).

The Virtual Router Redundancy Protocol (VRRP) is a computer networking protocol that provides for automatic assignment of available Internet Protocol (IP) routers to participating hosts. This increases the availability and reliability of routing paths via automatic default gateway selections on an IP subnetwork.

The Neighbor Discovery Protocol (NDP), or simply Neighbor Discovery (ND), is a protocol of the Internet protocol suite used with Internet Protocol Version 6 (IPv6). It operates at the link layer of the Internet model, and is responsible for gathering various information required for network communication, including the configuration of local connections and the domain name servers and gateways.

Cisco Express Forwarding (CEF) is an advanced layer 3 switching technology used mainly in large core networks or the Internet to enhance the overall network performance. Although CEF is a Cisco proprietary protocol other vendors of multi-layer switches or high-capacity routers offer a similar functionality where layer-3 switching or routing is done in hardware instead of by software and the (central) CPU.

Dynamic Multipoint Virtual Private Network (DMVPN) is a dynamic tunneling form of a virtual private network (VPN) supported on Cisco IOS-based routers, and Huawei AR G3 routers, and on Unix-like operating systems.

A routing protocol specifies how routers communicate with each other to distribute information that enables them to select routes between nodes on a computer network. Routers perform the traffic directing functions on the Internet; data packets are forwarded through the networks of the internet from router to router until they reach their destination computer. Routing algorithms determine the specific choice of route. Each router has a prior knowledge only of networks attached to it directly. A routing protocol shares this information first among immediate neighbors, and then throughout the network. This way, routers gain knowledge of the topology of the network. The ability of routing protocols to dynamically adjust to changing conditions such as disabled connections and components and route data around obstructions is what gives the Internet its fault tolerance and high availability.

In network routing, the control plane is the part of the router architecture that is concerned with drawing the network topology, or the information in a routing table that defines what to do with incoming packets. Control plane functions, such as participating in routing protocols, run in the architectural control element. In most cases, the routing table contains a list of destination addresses and the outgoing interface(s) associated with each. Control plane logic also can identify certain packets to be discarded, as well as preferential treatment of certain packets for which a high quality of service is defined by such mechanisms as differentiated services.

In computer networking, the link layer is the lowest layer in the Internet protocol suite, the networking architecture of the Internet. The link layer is the group of methods and communications protocols confined to the link that a host is physically connected to. The link is the physical and logical network component used to interconnect hosts or nodes in the network and a link protocol is a suite of methods and standards that operate only between adjacent network nodes of a network segment.

References

  1. 1 2 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.
  2. 1 2 "NHRP". Cisco. Retrieved 17 June 2016.
  3. 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.
  4. Cansever, Derya H. (April 1998). "NHRP Protocol Applicability Statement". tools.ietf.org. Retrieved 17 June 2016.
  5. Rouse, Margaret. "What is Next Hop Resolution Protocol (NHRP)? - Definition from WhatIs.com". SearchNetworking. Retrieved 17 June 2016.
  6. 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.
  7. Ahmad, Khalid (2 April 2004). Sourcebook of ATM and IP Internetworking. John Wiley & Sons. p. 360. ISBN   9780471660941 . Retrieved 18 June 2016.
  8. Dan, Grossman; Juha, Heinanen (September 1999). "Multiprotocol Encapsulation over ATM Adaptation Layer 5". tools.ietf.org.
  9. 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.