Has Anybody seen this VPC error on the 5k?

Endorsed Question
Mar 29th, 2010

Ok, my VPC is up and working for all my devices except my connection to the uplink switch. It is a sinle 3750 with port channles consisting of 4 interfaces. It is connected to two 5010s. I show the following error when I show VPC

"vpc port channel mis-config due to vpc links in the 2 switches connected to differnt partners"

Google does not have much on this error and this is the first time I have seen this. Any idea on what might casue this?

Thanks for any help.

I have this problem too.
2 votes
Cisco Endorsed by tcerling
Network Technol... about 6 years 5 months ago

Essentially to fix this, remove the vpc from the port-channel on both cores and re-add it back in. if you do a show lacp interface for that port you can see the details of the MAC addresses it's using for the 3750 stack. We had this problem on a 3750 stack and going to n7k

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allan.thomas Mon, 03/29/2010 - 14:24

Hi Justin,

I have not specifically come across this error before, but it seems to suggest that both your vpc peer devices do not recognise the 3750 as a single switch, but two separate entities, thus perceive the links as separate.  Is the 3750 a stack of switches where you have distributed the etherchannel uplinks across seperate switches in the stack, commonly referred to as cross-stack Etherchannel?

Ensure that all four uplinks on the 3750s are configured within the same port-channel group using LACP (mode active), similarly that the N5K uplinks are configured or associated with the same port-channel and vpc identifier.  Could you post the configuration of your uplink from the 3750(s), and N5K uplinks to the 3750 and peer-link and keep-alive link.

If you do a show interface trunk on the N5K, do any vlans show not forwarding and that are err-disabled, this suggest that the incorrect VLANs are not consistent across the uplinks.

Hope this helps.

Allan.

kiliasov Thu, 06/24/2010 - 13:27

I had similat error with N7K.

Every time I reload stack master it would shutdown the vPC to 3750 stack.

It's the way 3750 handles MAC address for master switch.There's no "virtual MAC" for the whole stack. It's always the MAC of stack master used for identification. When it goes down, new master is elected and it's MAC is used.

So from the vPC point of view all of a sudden you have 2 LACP id's for one port-channel. vPC thinks it's connected to 2 diferent devices, suspends vPC link.

To avoid this try:

stack-mac persistent timer 0

Network Technol... Thu, 06/24/2010 - 21:24

Essentially to fix this, remove the vpc from the port-channel on both cores and re-add it back in. if you do a show lacp interface for that port you can see the details of the MAC addresses it's using for the 3750 stack. We had this problem on a 3750 stack and going to n7k

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