Cisco Cisco 3600 Series 2-Port Channelized E1 ISDN-PRI Balanced NM Livre blanc
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Figure 17.
Abbreviated Output From the “show switch virtual redundancy” CLI with Quad-Sup Uplink Forwarding Enabled
Configuration Synchronization
When the redundancy-framework progression between the active supervisor engine and standby supervisor
engine is reached, the configuration is synchronized between active virtual switch and standby virtual switch.
The configuration file contains the configuration for the entire Cisco Virtual Switching System, and overwrites the
configuration that exists on the standby virtual switch. Both the bulk configuration synchronization and the
incremental configuration synchronization are sent through internal control messages across the VSL. As a result,
the configuration in the standby virtual switch NVRAM is overwritten.
Virtual Switch Priorities and Switch Preemption
Because the Cisco Virtual Switching System consists of two chassis merged into a single entity, you can designate
a particular physical switch to prefer an active role, while its peer prefers the standby role. This designation is
usually determined by the following by default:
If switches are initiated at different times, then the switch that is initiated first becomes the active virtual switch.
If the switches are initiated simultaneously, the switch with the lower switch ID becomes the active virtual switch.
You can alter the default behavior by using the Virtual Switch Priorities feature and the Switch Preemption function.
Virtual Switch Priorities
Virtual Switch Priorities are assigned to each member of the Cisco Virtual Switching System under the Virtual
Switch Configuration mode. By influencing the weighting of the priorities of each switch, you can deterministically
define which physical switch will prefer the active virtual switch role or the standby virtual switch role.
A sample configuration follows:
vss#conf t
Enter configuration commands, one per line. End with CNTL/Z.
vss(config)#switch virtual domain 10