HSRP and vPC

[michael.luo]

There are many articles talking about HSRP and vPC, such as:

http://www.dslreports.com/faq/17829

http://www.jeremyfilliben.com/2010/08/hsrp-vpc-and-vpc-peer-gateway-command.html

http://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/sw/design/vpc_design/vpc_best_practices_design_guide.pdf

http://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/design_guide_c07-625857.html#_Toc271759462

Yes, I understand L2 traffic will be sent to multiple links regardless of who's the active HSRP router.  I also understand the G flag was set so both HSRP router can forward L3 traffic.

But all these happen automatically.  There's no configuration difference between a vPC HSRP and non-vPC HSRP.  Was that correct?  If not, what special configuration we need for HSRP in vPC environment?  Thanks!

[Paul Chapman · Accepted solution]

Hi Michael -

That is correct, there is nothing particularly special about the HSRP configuration.  There are a couple of small corner cases to consider (which are listed in the vPC Best Practices Guide).

1. Use "peer-gateway" in your vPC domain configuration to fix a known ARP issue with certain storage systems.  It is non-impacting even if you don't have an affected system, and is  considered a best practice.
2. For a given set of VLANs / L3 networks, don't run HSRP on more than 2 vPC connected Nexus switches.  Meaning if you have 2 or more vPC pairs connected to each other with a back to back vPC, only enable HSRP on one vPC pair.  I've seen some comments about this, but don't have a link.

HTH

PSC