Specifications

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Cisco Wide Area Application Services Command Reference
OL-11817-01
Chapter 3 CLI Commands
(config-if) standby
Device Modes application-accelerator
central-manager
Usage Guidelines You can configure one or more interfaces to act as a backup interface (a standby interface) for another
interface on a WAAS device. This feature is called “standby interface support.” Standby groups, which
are logical groups of interfaces, are used to implement this feature. When an active network interface
fails (because of cable trouble, Layer
2 switch failure, high error count, or other failures) and that
interface is part of a standby group, a standby interface can become active and take the load off the failed
interface.
There must be at least two interfaces in a standby group. Interfaces that are part of a standby group are
called “member interfaces.” After you create a standby group, you define which interfaces should be
assigned to this logical group. As part of defining the member interfaces, you specify the priority of each
member interface in a standby group. The member interface with the highest assigned priority is the
active interface for that particular standby group. If the active interface fails, the operational member
interface with the next highest priority in the standby group comes up, and so forth. If all member
interfaces of a particular standby group are down and then one of the member interfaces comes up, the
WAAS software detects this situation and brings up the standby group on the member interface that just
came up.
The failure or failover of member interfaces within a standby group triggers alarms and traps (if alarms
and traps are enabled on the WAAS device). Alarms are sent out when failover occurs between member
interfaces in a standby group. Specifically, minor alarms are sent out when member interfaces fail, and
these alarms are cleared automatically when the interface failover has been successfully completed.
Major alarms are sent out if the standby group goes down (that is, no member interface in a standby
group can be brought up.)
Note A physical interface can belong to more than one standby group. Consequently, a single interface can act
as a standby interface for more than one standby group.
To configure standby interfaces, interfaces are logically assigned to standby groups. The following rules
define the standby group relationships:
• Each standby group is assigned a unique standby IP address, shared by all member interfaces of the
standby group. The IP address of the standby group is shared among the member interfaces;
however, only the active interface of the standby group uses this shared IP address at any one time.
This shared IP address is configured as an alias on the active interface.
• Configure the duplex and speed settings of the member interfaces for better reliability.
• If all the member interfaces of a standby group fail and then one recovers, the WAAS software brings
up the standby group on the operational member interface.
• If a physical interface is a member of a port channel group, it cannot join a standby group. Likewise,
if a physical interface is a member of a standby group, it cannot join a port channel group.
• A standby group comprises two or more interfaces.
• The maximum number of standby groups on a WAAS device is four.