Cisco Cisco 1700 2600 3600 3700 Series VPN Module White Paper
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vss(config-vs-domain)#switch 1 priority 110
*Jul 7 08:59:11.913: %VSLP-SW1_SPSTBY-5-RRP_RT_CFG_CHANGE: Configured priority
value
value
is different from operational value.
Change will take effect after config is saved and switch is reloaded.
vss(config-vs-domain)#switch 2 priority 100
vss(config-vs-domain)#^Z
vss#
Notice from this configuration that the higher-priority value (110) assumes the active virtual switch role and the
default priority is set to 100 (Figure 18).
Figure 18. Virtual Switch Priorities
After you save the configuration, you can verify the roles of each virtual switch member with the following
command:
vss#sh switch virtual role
Switch Switch Status Preempt Priority Role Session ID
Number Oper(Conf) Oper(Conf) Local Remote
------------------------------------------------------------------
LOCAL 1 UP FALSE(N) 110(110) ACTIVE 0 0
REMOTE 2 UP FALSE(N) 100(100) STANDBY 6179 1085
In dual-active recovery mode: No
Note that the switch priorities affect role determination if both virtual switches are initiated simultaneously. If either
switch (regardless of priority) is initiated prior to the subsequent switch, it always assumes the role of the active
virtual switch. This behavior changes only if the Switch Preemption feature is configured.
Switch Preemption
As mentioned previously, you can determine virtual switch roles by boot order, switch ID, and switch priorities.
However, after you determine the roles, you cannot change them without manual intervention. It may be desirable,
however, to always configure a particular physical switch to assume the active virtual switch role. You can achieve
this configuration with the Switch Preemption feature.
Switch Preemption works by comparing the Virtual Switch Priorities of the two individual switches after they are
both brought online. If the virtual switch with the higher priority has the Switch Preemption feature configured and
the current role of the higher-priority virtual switch is in standby mode, the current active virtual switch performs a
SSO switchover after a preconfigured period of time, so that the virtual switch with the higher switch priority takes
over as the active virtual switch (Figure 19).