The other day I was asked,

What interface should we use for the vPC peer-keepalive link?

In fact this is a good question, considering the fact you wouldnt want to burn a SFP port just for the peer keepalive.

After a short amount of digging, the answer was found within Cisco's - Best Practices for Virtual Port Channels (vPC).

When building a vPC peer-keepalive link, use the following in descending order of preference:

  1. Dedicated link(s) (1-Gigabit Ethernet port is enough) configured as L3. Port-channel with 2 X 1G port is even better.
  2. Mgmt0 interface (along with management traffic)
  3. As a last resort, route the peer-keepalive link over the Layer 3 infrastructure