Failure of peer-link and VSL

[Marc du]

Hi Cisco Experts

on 6500 based VSS what happened when the VSL between switches fail

on the N7K/5K , what happened when the peer-link failed

thanks

[Mark Malone · Accepted solution]

hi

6500

If the VSL fails completely, the VSS standby chassis assumes that the VSS active chassis has failed, and initiates a switchover. After the switchover, if both chassis are VSS active, the dual-active detection feature detects this condition and initiates recovery action.

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/vss.html

Nexus

if peer-link is up but keep alive link down , nothing happens except peer-link becomes keep-alive temporarily

if both fail you will get a scenario called split brain depending on design , could end up in a loop , both become active , both send same stp info & bridge ids which can cause confusion on the network

[ahmedshoaib · Accepted solution]

Hi;

In case of vPC peer-link fail and keepalive is up, then Secondary chassis will disable all vPC ports to prevent loops. 

Please find below Nexus vPC failover scenario:

https://supportforums.cisco.com/document/138636/vpc-failover-scenarios-and-troubleshooting-checklist#Failure_Reaction:_vPC_peer-link_failure_link_loss 

Thanks & Best regards;

[Marc du]

thanks to all of you guys