back to back vPCs with layer 3 port-channeling

Answered Question
Nov 15th, 2012

hello all. is it possible to run Layer 3 back to back VPCs btw 2 N 7009s (sup2 running f2 cards)? If so, do I put the same port-channel interface IP address on each VPC peer?

please see sample configuration below for one of the vpc domains. Thanks

vpc domain 2

  peer-keepalive destination 10.10.10.2 source 10.10.10.1 vrf peer-keepalive

peer-switch

!

interface port-channel1

  description vpc_peer-link

switch

  switchport mode trunk

  vpc peer-link

  spanning-tree port type network

shut

!

interface e3/47-48,e4/47-48

  description vpc_peer-link

switch

  switchport mode trunk

channel-group 1 mode active

shut

!

interface port-channel50

  description L3_TO_DISTRIBUTION

  no switch

ip address 10.1.1.1/30   --- do I need this same IP to be configured on the other peer

  vpc 50

!

interface e3/1,e4/1

  description L3_TO_DISTRIBUTION

  no switch

no ip add

channel-group 50 mode active

I have this problem too.
0 votes
Correct Answer by Chad Peterson about 1 year 5 months ago

L3 port channels are not supported on vPCs.  When connecting to a layer 3 host the best method is to use independent /30 links.  Trying to do L3 over a vPC isn't providing any additional redundancy and load balancing can already be achieved over layer three links via ECMP.

Take a look at this presentation PDI gave at a recent DC Byte-Z session.  We cover supported L3 topologies in vPC environments:

https://communities.cisco.com/docs/DOC-31528

Hope that helps

Chad

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Correct Answer
Chad Peterson Fri, 11/16/2012 - 06:10

L3 port channels are not supported on vPCs.  When connecting to a layer 3 host the best method is to use independent /30 links.  Trying to do L3 over a vPC isn't providing any additional redundancy and load balancing can already be achieved over layer three links via ECMP.

Take a look at this presentation PDI gave at a recent DC Byte-Z session.  We cover supported L3 topologies in vPC environments:

https://communities.cisco.com/docs/DOC-31528

Hope that helps

Chad

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Posted November 15, 2012 at 3:42 PM
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