Chapter 23: Configuring Vrrp; Vrrp Overview - Enterasys C5G124-24 Configuration Manual

This chapter describes the Virtual Router Redundancy Protocol (VRRP) feature and its
configuration. VRRP is available only on those fixed switch platforms that support advanced
routing and on which an advanced feature license has been enabled.
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VRRP Overview

Configuring VRRP
Terms and Definitions
VRRP Overview
Virtual Router Redundancy Protocol (VRRP) is an election protocol capable of dynamically
assigning responsibility for a virtual router to one of the VRRP routers on a LAN. A virtual router
is an abstract object managed by VRRP that acts as a default router for hosts on a shared LAN. It
consists of a Virtual Router Identifier (VRID) and a set of associated IP addresses across a common
LAN that define virtual router members. A VRRP router is a router with the VRRP protocol
running on it. A VRRP router may participate in and back up one or more virtual routers.
VRRP specifies an election protocol that dynamically assigns responsibility for a virtual router to
one of the VRRP routers on a single subnet. The elected VRRP router is called the master. The
router master controls the IP addresses associated with a virtual router. The master forwards
packets sent to these IP addresses. The VRRP election process provides dynamic fail over of
forwarding responsibility to another VRRP router should the current master become unavailable.
This allows any of the virtual router IP addresses on the LAN to be used as the default first hop
router by end-hosts. In this way, VRRP provides a higher availability default path without
requiring configuration of dynamic routing or router discovery protocols on every end-host.
Statically configured default routes can represent a single point of failure that can result in a
catastrophic event, isolating all end-hosts that are unable to detect any alternate available path.
VRRP is designed to eliminate the single point of failure inherent in the static default routed
environment.
VRRP is defined in RFC 5798.
Note: VRRP is an advanced routing feature that must be enabled with a license key. If you have
purchased an advanced license key, you must activate your license as described in the chapter
entitled "Activating Licensed Features" in order to enable the VRRP command set. If you wish to
purchase an advanced routing license, contact Enterasys Networks Sales.
Figure 23-1
Configuring VRRP
on page 23-2 illustrates a basic VRRP topology.
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