Virtual Router Redundancy Protocol

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VRRP (Virtual Router Redundancy Protocol)
Family: Internet protocol family
Operation area:

High availability
of routers

VRRP on the TCP / IP protocol stack
Mediation VRRP
Network access Ethernet Token
FDDI ...

RFC 5798 (2010)

The Virtual Router Redundancy Protocol ( VRRP ) is a procedure for increasing the availability of important gateways in local networks through redundant routers .

The VRRP was developed by Ascend Communications , DEC , IBM , Microsoft and Nokia in 1998. Today it is also available in the routers of many other manufacturers such as Alcatel , Cisco or DrayTek . The aim was to establish an open standard that addresses the problem of the failure safety of data paths, namely the availability of the so-called standard gateway in local networks.


When routing data packets through networks, the failure of sections on the way to the destination is usually counteracted by dynamic routing . However, if the first router on a route fails, this error cannot be remedied by dynamic routing, since a host normally only knows one static standard gateway and usually only supports one.

If the first router, the standard gateway, fails, the affected hosts are cut off from communication with the outside world, even if there are still active routers available in the same subnet.

This is where the VRRP comes in. Several physical routers are combined into a logical group, which is now presented in the network as a logical virtual router.

To do this, a virtual IP address and a virtual MAC address are assigned to the logical router . One of the routers within the group is defined as the virtual master router. This then binds the virtual MAC and the virtual IP address to its network interface and informs the other routers in the group, which act as virtual backup routers.

If the master router fails, the virtual IP address and the virtual MAC address are transferred to one of the backup routers within three seconds, which then becomes the new master router. Both the MAC and the IP address are transferred so that the affected hosts do not have to update their ARP cache. The consequences of the failure of the first router on the route can thus be reduced. This redundancy principle is called hot standby .

Uses and alternatives

Since VRRP uses Cisco patents , the developers of the free OpenBSD operating system have developed an alternative protocol, CARP . The web server software Nginx Plus has implemented the VRRP protocol with release R6, which is intended to achieve high availability of the web server.

See also

Web links

  • Current version: RFC 5798 - Virtual Router Redundancy Protocol (VRRP) Version 3 for IPv4 and IPv6, March 2010
  • Old version: RFC 3768 - Virtual Router Redundancy Protocol, April 2004 (obsolete, successor is RFC 5798 )

Individual evidence

  1. VRRP
  2. Owen Garett: Announcing NGINX Plus Release 6 with Enhanced Load Balancing, High Availability, and Monitoring Features . nginx . 2015. Retrieved June 3, 2015.