First Hop Redundancy Protocols
Encyclopedia
A First Hop Redundancy Protocol (FHRP) is a computer networking protocol which is designed to protect the default gateway
used on a subnetwork
by allowing two or more routers to provide backup for that address; in the event of failure of the/an active router, the backup router will take over the address, usually within a few seconds. In practice, such protocols can also be used to protect other services operating on a single IP address, not just routers.
Examples of such protocols include (in approximate order of creation):
Default gateway
In computer networking, a gateway is a node on a TCP/IP network that serves as an access point to another network. A default gateway is the node on the computer network that the network software uses when an IP address does not match any other routes in the routing table.In home computing...
used on a subnetwork
Subnetwork
A subnetwork, or subnet, is a logically visible subdivision of an IP network. The practice of dividing a network into subnetworks is called subnetting....
by allowing two or more routers to provide backup for that address; in the event of failure of the/an active router, the backup router will take over the address, usually within a few seconds. In practice, such protocols can also be used to protect other services operating on a single IP address, not just routers.
Examples of such protocols include (in approximate order of creation):
- Hot Standby Router ProtocolHot Standby Router ProtocolHot Standby Router Protocol is a Cisco proprietary redundancy protocol for establishing a fault-tolerant default gateway, and has been described in detail in RFC 2281....
(HSRP) - CiscoCiscoCisco may refer to:Companies:*Cisco Systems, a computer networking company* Certis CISCO, corporatised entity of the former Commercial and Industrial Security Corporation in Singapore...
's initial, proprietary standard - Virtual Router Redundancy ProtocolVirtual Router Redundancy ProtocolThe Virtual Router Redundancy Protocol is a computer networking protocol that provides for automatic assignment of available Internet Protocol routers to participating hosts...
(VRRP) - an open standard protocol - Common Address Redundancy ProtocolCommon Address Redundancy ProtocolThe Common Address Redundancy Protocol or CARP is a protocol which allows multiple hosts on the same local network to share a set of IP addresses. Its primary purpose is to provide failover redundancy, especially when used with firewalls and routers. In some configurations CARP can also provide...
(CARP) - free, (patent) unencumbered alternative to Cisco's HSRP - Extreme Standby Router Protocol (ESRP) - Extreme NetworksExtreme NetworksExtreme Networks, founded in 1996, is a publicly listed company that designs, builds, and installs Ethernet network solutions for enterprise and Carrier Class networks.-Corporate History:Extreme Networks is located in Santa Clara, California...
' proprietary standard with fast failover and also layer 2Data link layerThe data link layer is layer 2 of the seven-layer OSI model of computer networking. It corresponds to, or is part of the link layer of the TCP/IP reference model....
protection - Gateway Load Balancing ProtocolGateway Load Balancing ProtocolGateway Load Balancing Protocol is a Cisco proprietary protocol that attempts to overcome the limitations of existing redundant router protocols by adding basic load balancing functionality....
(GLBP) - a more recent proprietary standard from Cisco that permits load balancing as well as redundancy - Split multi-link trunking (SMLT) - An Avaya redundancy protocol
- NetScreen Redundancy Protocol (NSRP) - A Juniper Networks proprietary router redundancy protocol providing load balancing