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If vPC peer-link goes down then how vpc will work

olly ahmed
Level 1
Level 1

Can anyone describe me the situation when all the vPC peer-link between two Nexus goes down. Does both the switches forward traffic independently ?

3 Replies 3

Aninda Chatterjee
Cisco Employee
Cisco Employee

Hi,

There are a few scenarios to consider when you talk about the vPC peer-link going down.

One scenario is where the vPC peer-link fails, however, the keepalive link is up. This means that the vPC peers continue to exchange keepalives. In such a situation, the secondary vPC peer suspends its vPCs. You would see something similar to the following on the secondary vPC peer if you take a look at the vPC itself:

N7K-2# show int po10
port-channel10 is down (suspended by vpc)
admin state is up
 vPC Status: Down, vPC number: 10
  Hardware: Port-Channel, address: 0000.0000.0000 (bia 0000.0000.0000)
  MTU 1500 bytes, BW 100000 Kbit, DLY 10 usec
  reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, medium is broadcast
  Port mode is trunk
  auto-duplex, 10 Gb/s

*snip*

Another scenario is where the keepalive link is down and then the vPC peer-link goes down. In such a case, there is a split brain and both vPC peers move into a primary peer role (primary stays primary, while the secondary moves into an operational primary role) and behave as independent switches.

Thanks for your clarification.

Hi,

Please find the vPC failover scenario in detail:

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

Thanks & Best regards;

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