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Deleted VSL portchannel in 6500 VSS

Level 1
Level 1

During a deployment of VSS on a pair of 6500's, I was making configuration changes on the active switch 1 and accidentally deleted the VSL portchannel on switch 2 (no interface port-channel 2). As a result, the VSL between the switches was lost. From the perspective of switch 1, all chassis 2/x/y cards were now down/down and could not be configured.

At this point, dual-active detection was not yet enabled. When connected to switch 2, it appeared the erroneous config was not yet synched over before the VSL was deleted, so the portchannel still existed. From switch 1, I received an error when trying to re-join the interfaces into the portchannel about being unable to make configuration changes until mismatch was resolved.

"show switch virtual redundancy mismatch" showed that the portchannel existed on switch 2 but not 1, so there was clearly some sort of communication still going across the VSL but I was prevented from correcting the mismatch.

Due to time constraints, I could not perform further recovery attempts or gather more logs from the session and had to convert back to standalone mode. Is this an irrecoverable error? Would over-writing the startup-config in switch1 and reloading have worked?

1 Reply 1

Haihua Rong
Level 1
Level 1


Indeed, that should have worked because we still have the original configuration on the nvram. Another workaround could be:

Dual active detected:

Switch 1 as active chassis

Switch 2 as standby chassis.

Step 1: Remove the VSL from standby chassis

Step 2: Reload the standby chassis. At this point switch 1 it is still the active chassis.

Step 3: Do no shutdown to the portchannel 2 and then wr. At this point we fixed the mismatch config for the port channel

Step 4: Reconnect the VSL link and everything should be fine because the standby chassis will sync to the active chassis due to the fact that the has the same config than the active one.


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