[c-nsp] HSRP to VRRP migration

[Cydon Satyr]

Hello guys. We have a bunch of redundant router Cisco pair routers, that
are running HSRP, that needs to be migrated to VRRP.

The question is, could this be down with 0 downtime?

My guess is, if we replace backup HSRP router to run VRRP master, then
gratious-arp war could start, with both routers trying to send proper mac
address info to LAN. I guess with some filter hosts could be convinced to
use VRRP's mac address... or something.

I understand  a proper maintenance window should be ordered, but, could
this be done with no downtime (or at least near 0, just so hosts update arp
table)? Any ideas?

Regards!