Switch Up&Running - Uplinks suddenly down

[ciscothomas]

Hi All

Yesterday evening we had a strange behaviour of our networking infra.

Simplified we use a 4500X VSS-Cluster where our Access Switches are terminating (Port-Channel, Spanning-Tree Rings, Star)

Suddenly almost all switches where disconnected - but Up&Running - SFP Interfaces and all sides where down/notconnect. 

After the Access Switches (C2960X, C2960XR,...) where rebooted all was fine again.

Log's are saying nothing.

Have you ever seen a situation like this and may have a hint what is the cause?

Thanks in advance

BR Thomas

[marce1000]

 - About logging : make sure to , for instance, configure syslogging on all switches in the network; to a central syslog server, this gives the opportunity to review events afterwards on the syslog server (same for snmp traps to  an snmp trap receiver).

 M.

[Leo Laohoo]

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@ciscothomas wrote:

Log's are saying nothing.

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It won't because the default behaviour of the ports in a Catalyst 4K and 6K is that they don't log into syslog the state of the link:  If the ports go down or up, it won't show up in the "sh log".  This is the default behaviour. 

What firmware is the 4500X running on?

[marce1000]

 - For enhanced logging statuses of important ports and up links add : logging event link-status  to the particular port configuration.

 M.

[balaji.bandi]

what is the version of IOS you running what supervisors here.

how is your VSL and Dual active setup done here..do you have high level topology here to review.

also at the time of all the links were down, what was the logs ?