HSRP on a /30?

[robert.lorrison]

My datacenter is looking at installing a second ASR 1001 alongside our current external router and configuring HSRP, however, for administrative reasons we only have a /30 on the interface leading out to the cloud.  Is there a way to make this work with what we have or do I need to beg, borrow, or steal for a /29 subnet?

[Jon Marshall · Accepted solution]

Consider using VRRP where the VIP can be the physical IP on one of the routers. 

Or yes, find a /29.

Jon

[robert.lorrison]

I thought as much, VRRP still leaves me one IP short 😩.

Thanks for the quick response though!

[Jon Marshall]

Haven't configured VRRP on ASR's but why does it leave you one short ? 

A /30 gives you two IPs and the virtual IP with VRRP does not have to be a separate IP as it does with HSRP ie. it can be one of the physical IPs you assign to an interface. 

Jon

[robert.lorrison]

Because one of the IPs is already being used by the distant end in that subnet.

[Jon Marshall]

Okay, that makes sense.

A /29 it is then :) 

Jon