vPC - peer gateway and peer switch

[Steven Williams]

I understand that we need to use peer gateway on a vPC pair when HSRP is running, but why do we use peer switch if the vPC pair is not the root or seconday root of the network? Does it matter they send out different BIDs? What would be the worst case scenario when not using peer switch?

[sean_evershed]

If you read the vPC Best Practices Design Guide the peer-switch feature reduces convergence time as a result of a spanning-tree failure from 3 seconds to sub-second.