vpc configuration issue in N5K.

[bhaskaran-s]

I have an issue with vpc in N5K. I am trying to upgrade the existing 3750 stack router with 2 Nexus 5596 running VPC between them. For the transition I have planned to create a channel between 3750 stack and 5596's. Once this environment is set, my plan is to migrate all the access switches to N5k.

The issue is when I connect the 3750 port channel to both N5Ks, all the Vlans on 3750 started to flap. If I connect the port channel to only one N5K everything is normal; but when I connect the port channel to both N5K running VPC, vlans are flapping. Any idea what is going wrong here? Am I missing something?

N5k-1:

vpc domain 2

  role priority 1

  peer-keepalive destination x source y

interface port-channel1
  description vpc peer-link_to_N5K-C5596
  switchport mode trunk
  vpc peer-link
  switchport trunk native vlan 99
  spanning-tree port type network
  spanning-tree guard loop
  speed 10000

interface port-channel99
  description to 3750-stack
  switchport mode trunk
  vpc 99
  switchport trunk native vlan 99
  switchport trunk allowed vlan 101-110 

  spanning-tree port type normal
  speed 1000

N5k-2

vpc domain 2
  role priority 1
  peer-keepalive destination y source x

interface port-channel1
  description vpc peer-link_to_N5K-C5596
  switchport mode trunk
  vpc peer-link
  switchport trunk native vlan 99
  spanning-tree port type network
  spanning-tree guard loop
  speed 10000

interface port-channel99
  description 3750-stack 

  switchport mode trunk
  vpc 99
  switchport trunk native vlan 99
  switchport trunk allowed vlan 101-110 

  spanning-tree port type normal
  speed 1000

Thanks,

Bhaskar

[Jerry Ye]

N5k-1:

vpc domain 2

  role priority 1

  peer-keepalive destination x source y

:

N5k-2

vpc domain 2
  role priority 1
  peer-keepalive destination y source x

You are having role priority with the same value on both switches. Make N5k-2 into a higher number (higher number means less priority). Please test it after you've changed and let me know the result.

HTH,

jerry

[bhaskaran-s]

HI,

I connected the the 3750 to only one N5K on a port channel and managed the migration. The role priority command was not an issue because show VPC indicates that only one device as Primary. Due to the project pressure I had to go ahead with the migration and remove the 3750 from the network which is completed successfully now. Thanks for your inputs.

Thanks,

Bhaskar