HSRP: Virtual/Interface IP address allocation

[rsgamage1]

Hi,

This query is regarding the virtual IP address allocation in HSRP.

What if the virtual IP chosen to be of a different subnet from the interface IP?

According to RFC 2281, this is something achievable though I'm curious to know the consequences(if any).

RFC 2281 says "The IP address SHOULD belong to the primary subnet in use on the LAN, but MUST differ from the addresses allocated as interface addresses on all routers and hosts

on the LAN, including virtual IP addresses assigned to other HSRP groups."

One question remains with respect to the subnet being used by the virtual address.

Will this address take the subnet mask of the interface address, or will just be a /32.

The other question is: what are the cons of having these assignments from two different networks?

[rsgamage1]

I've deployed it in the production network and seems to be working fine.

Because of the Virtual IP/MAC concept, I think it would not give any trouble as long as reachability is maintained.

Especially for a fail-over scenario this would be feasible and duplicate IP address (Secondary) issue wouldn't be of a serious concern.

[rsgamage1]

Wouldn't this be a feasible solution for remote provider assigned IP subnet(typically /30) for the interconnection?