Standby Command Configuration

Cluster Management software implements the Hot Standby Router Protocol (HSRP), which transfers responsibilities to another switch if the command switch becomes unavailable. The HSRP group is composed of cluster members that are designated to take command if needed. The transfer of responsibilities to a standby switch (failover) is transparent.

With the Standby Command Configuration window, you can:

Note: Failovers normally require 13 to 17 seconds to reestablish connections to member switches, but this process can require as long as 2 minutes depending on the availability of member information being transferred.

Creating an HSRP Group

The Candidates list contains the name of all cluster members that are qualified standby switches: command-capable switches with the required software that are available to assume responsibility. On this list, switches are listed in order of eligibility to serve as the cluster command switch. A candidate's eligibility is determined primarily by the number of links that it has to other cluster switches and its speed (see the Cisco IOS Desktop Switching Software Configuration Guide for details).

If HSRP is not configured on the cluster, the Selected list contains only the name of the command switch with the CC (cluster command) designation. If HSRP is configured, this list contains the names of the active command (AC) switch, the standby command (SC) switch, and one or more passive standby (PC) switches. A passive standby replaces the switch listed above it if the current standby (SC) becomes the active command switch.

Switches listed in the Selected list make up the current cluster HSRP group. These switches share a virtual IP address, which is assigned to the cluster. Because a network can contain several HSRP groups, each HSRP group is identified by a number.

Note: After a virtual IP is assigned to the cluster HSRP group, always use the virtual IP address to access the command switch.

To create an HSRP group and enable the standby:

  1. Select a standby switch from the Candidates list and click Add.
    The standby switch moves to the Selected list with an SC designation, and the command switch receives its active command (AC) designation.
  2. Enter an IP address in the Virtual IP Address field.
    The virtual IP address is assigned to the entire HSRP group; switches use this address if they are called on to act as the command switch. The virtual IP address must be in the same subnet as the IP addresses of all switches on the Candidates list.
  3. Enter an HSRP group number in the Group Number field.
    Numbers from 0 through 255 are valid HSRP group numbers. If the cluster is in a network where other HSRP groups are configured, use a unique HSRP number. If necessary, consult with your network administrator before assigning this number.
    Note: If you change your mind about any entry, click Cancel to close the window without saving your changes.
  4. Click OK to put your changes in effect and close the Standby Command Configuration window.

Adding and Removing Switches in an HSRP Group

You can add any switch in the Candidates list to the Selected list to add it to the cluster HSRP group. You can remove any switch from the Selected list except the active command (AC) switch.

Note: If you remove all standby switches from the Selected list, the cluster HSRP group is removed.

To add a switch to the HSRP group:

  1. Select a switch from the Candidates list on the Standby Command Configuration window.
  2. Click Add.
    The switch is moved to the Selected list.
  3. Click OK to put your change in effect and close the Standby Command Configuration window.

To remove a switch from the HSRP group:

  1. Select a switch from the Selected list on the Standby Command Configuration window.
  2. Click Remove.
    The switch is moved to the Candidates list.
  3. Click OK to put your change in effect and close the Standby Command Configuration window.

Removing a Hot Standby Group

To remove an HSRP group, click Remove Standby Configuration. Then, click OK to put your changes in effect and close the Standby Command Configuration window.