Configuring Vrrp; Overview - HP MSR Series Configuration Manual

Configuring VRRP

Overview

Typically, you can configure a default gateway for every host on a LAN. All packets destined for other
networks are sent through the default gateway. As shown in
hosts can communicate with external networks.
Figure 6 LAN networking
Using a default gateway facilitates your configuration but requires high availability. Using more egress
gateways improves link availability but introduces the problem of routing among the egresses.
Virtual Router Redundancy Protocol (VRRP) is designed to address this issue. VRRP adds a group of
network gateways to a VRRP group called a virtual router. A VRRP group comprises one master and
multiple backups, but has only one virtual IP address. The hosts on the subnet only need to configure this
virtual IP address as their default network gateway for communicating with external networks.
The virtual IP address of the virtual router can be either of the following IP addresses:
• Unused IP address on the subnet where the VRRP group resides.
IP address of an interface on a router in the VRRP group.
•
In the latter case, the router is called the IP address owner. A VRRP group can have only one IP address
owner.
VRRP avoids single points of failure and simplifies the configuration on hosts. When the master in the
VRRP group on a multicast or broadcast LAN (for example, an Ethernet network) fails, another router in
the VRRP group takes over. The switchover is complete without causing dynamic route recalculation, route
re-discovery, gateway reconfiguration on the hosts, or traffic interruption.
VRRP operates in either of the following modes:
Standard mode—Implemented based on RFCs. For more information, see
•
• Load balancing mode—Extends the VRRP standard mode to distribute load across VRRP group
members. For more information, see
Figure
"VRRP load balancing
12
6, when the default gateway fails, no
"VRRP standard
mode."
mode."