VSS on 4500X (dual-active when VSL down)

[johnelliot6]

Hi,

Have a working VSS with 2 x 4500X's - Testing failover on them, and notice when I disconnect the VSL link, the standby swich reboots - Is this expected behaviour? (dual-active scenario?)

sw1-standby>

*Mar 24 16:02:28.837: %VSLP-3-VSLP_LMP_FAIL_REASON: STANDBY:Te2/1/16: Link down
*Mar 24 16:02:28.837: %VSLP-2-VSL_DOWN: STANDBY:  All VSL links went down while switch is in Standby role

*Mar 24 16:02:28.838: %EC-5-UNBUNDLE: STANDBY:Interface TenGigabitEthernet2/1/16 left the port-channel Port-channel10
*Mar 24 16:02:28.845: %C4K_REDUNDANCY-6-INIT: Initializing as ACTIVE supervisor
*Mar 24 16:02:28.874: %C4K_REDUNDANCY-3-COMMUNICATION: Communication with the peer Supervisor has been lost
*Mar 24 16:02:28.915: %C4K_REDUNDANCY-3-SIMPLEX_MODE: The peer Supervisor has been lost
*Mar 24 16:02:28.941: %EC-5-UNBUNDLE: Interface Te1/1/1 left the port-channel Po20
*Mar 24 16:02:28.947: %EC-5-UNBUNDLE: Interface TenGigabitEthernet1/1/16 left the port-channel Port-channel5
*Mar 24 16:02:58.120: %C4K_IOSINTF-5-LMPHWSESSIONSTATE: Lmp HW session UP on slot 11 port 16.
*Mar 24 16:03:14.117: %VSLP-5-VSL_UP:  Ready for control traffic

*Mar 24 16:03:17.115: %VSLP-5-RRP_MSG: Role change from Active to Standby and hence need to reload
*Mar 24 16:03:17.115: %VSLP-5-RRP_MSG: Reloading the system...
*Mar 24 16:03:18.266: %SYS-5-RELOAD: Reload requested by VSLP RRP event generator process. Reload Reason: VSLP HA role change from active to standby.
*Mar 24 16:03:18.597: %VSLP-3-VSLP_LMP_FAIL_REASON: Te2/1/16: Link down
*Mar 24 16:03:18.598: %VSLP-2-VSL_DOWN:   All VSL links went down while switch is in ACTIVE role

*Mar 24 16:03:18.598: %C4K_IOSINTF-5-LMPHWSESSIONSTATE: Lmp HW session DOWN on slot 11 port 16.

*Mar 24 16:03:18.797: %C4K_IOSINTF-5-TRANSCEIVERREMOVED: Slot=11 Port=1: Transceiver has been removed

*Mar 24 16:03:18.797: %C4K_IOSINTF-5-TRANSCEIVERREMOVED: Slot=11 Port=16: Transceiver has been removed

*Mar 24 16:03:19.809: %EC-5-UNBUNDLE: Interface Te2/1/1 left the port-channel Po20Please stand by while rebooting the system...

                                                                                                                               Restarting system.

[InayathUlla Sharieff · Accepted solution]

HI John,

Yes this is expected behaviour.

Explanation;

==========

If the VSL goes down and there is no protection mechanism in place then you

will have a dual-active scenario which will have to be dealt with manually

(and quickly). You may be able to use EEM as a backup to do some automated

shutdowns of interfaces if both the VSL and VSLP links go down. I have not

tested this, but I imagine it is possible.

Is it also possible to use Enhanced PAgP for the Dual Active Detection

Mechanism so that it does not share the same fibers as the VSLP Fast Hellos

and VSL ? This would require the switch running EPAgP to be dual-homed

across a more stable path.

Cisco VSS Dual-Active Detection

http://www.netcraftsmen.net/component/content/article/69-data-center/765-cisco-vss-dual-active-detection.html

HTH

Regards

Inayath.

*Plz dont forget to rate the usefull posts.

[Steven Williams]

So what does the failed VSS scenario look like when using just fast hellos since my downstream switches are Nexus 3k and will not support PAgP?

[balbaletabrez · Accepted solution]

Hi

It is normal.... The standby tries to become active once it senses vsl is down....


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