Posted on 2016-09-22
A 6506 VSS is experiencing a strange behavior. The VSS is formed with two etherchannel with t1/5/4, t1/5/5 and t2/5/4 and t2/5/5. We thought the behavior was caused by a bad VSL link at first on t1/5/5 and t2/5/5 when I see the logs below from the system. These events caused the active switch stop responding and couldn't process any traffic, a eigrp neighbor that's connected to only the active lost which makes me think the VSS is recalculating the role..etc. As I checked for the VSS to see if the standby was trying to become active or the history of the VSS role and other detail. I did not find any indication of the VSS role change but the one of the VSL cable fails. Also, there were no dual active detected.
Sep 8 15:27:39 EDT: %VSLP-SW2_SP-3-VSLP_LMP_FAIL_REASON: Te2/5/5: Link down
Sep 8 15:29:04 EDT: %VSLP-SW1_SPSTBY-3-VSLP_LMP_FAIL_REASON: Te1/5/5: Link down
Sep 8 15:29:04 EDT: %VSLP-SW2_SP-3-VSLP_LMP_FAIL_REASON: Te2/5/5: Link down
Sep 8 15:30:07 EDT: %VSLP-SW1_SPSTBY-3-VSLP_LMP_FAIL_REASON: Te1/5/5: Link down
After we received the new transceivers and cable. we swapped them out. The first 2 minutes were okay but the behavior came back after. This time, the port stated up, I didn't see any log indicate the link come down nor flop. As soon as we unplug the cable from the switch from both ports T1/5/5 and T2/5/5. The switch started to operate normal again. As for now, we're running the VSS via one cable. until i can schedule another maintenance window to troubleshoot this further. At this time, I wonder if anyone has experienced this same or similar issue.
May I ask what could be the issue here? why would the single link caused such behavior. The other VSL link was operating normally and keeping the VSS state the whole time.