User guide

ExtremeWarePx1 1.2 Command Reference Guide 165
5 Commands for Configuring Redundancy
This chapter describes the following commands:
¥ Commands for using VRRP
¥ Commands for conÞguring a default gateway
VRRP
To reduce downtime, you can deploy two Px-series application switches that provide redundancy using
Virtual Router Redundancy Protocol (VRRP), an industry standard failover mechanism (RFC 2338).
VRRP classes are used to classify virtual services into groups for fail-over. Up to 16 VRRP classes are
allowed. Each VRRP class is identiÞed by a unique virtual router ID (VRID).
When VRRP is enabled:
¥ The same services must be conÞgured on both application switches.
¥ Each service must be assigned to a particular VRRP class.
¥ When you conÞgure a given service on the two switches, you must use the same VRID for the
service on both switches.
Each Px-series application switch in the pair can be in either active or backup state on a particular
VRRP class. The active switch is the one that handles virtual services in that VRRP class. In the event of
failure of the active switch, the backup switch automatically takes over. At any given time, a particular
VIP will be active on one application switch onlyÑthe switch on which the corresponding VRRP class
is active.
The two switches operating in this mode are called VRRP peers.
In the simplest case (called active-passive VRRP), a single VRRP class is used for all services and one
switch is active on that VRRP class while the other switch is the backup. In the more general case
(called active-active VRRP), you conÞgure the switches so that the Þrst switch is active on one set of
VRRP classes and the other switch is active on a different, disjoint sets of VRRP classes.