HSRP Addressing

[tahequivoice]

Is it possible to use a different subnet, say a /30 private for the actual interfaces, and a public from another network as the floating IP, or must I burn up 3 publics in order for it to work? ?

interface Port-channel3.2

  encapsulation dot1Q 2

ip vrf forwarding helpme

ip address 10.100.4.2 255.255.255.252

standby version 2

standby 2 ip 99.100.110.1

standby 2 follow instructions

[vmiller]

Short answer is no.

All 3 need to be on a common subnet.

http://www.netcraftsmen.net/resources/archived-articles/441-hot-standby-routing-protocol.html

The good Dr. Welcher explains things quite well.

[InayathUlla Sharieff]

Hi Taheq,

As Vmiller said the answere is big " NO".

Your HSRP configuration (VIP  configuration of subnet should be same as the interface else it doesnt work).

Also you would get the following error when you configure different subnet range on hsrp standby interface.

% Warning: address is not within a subnet on this interface

config:

===

(Optional on all but one interface)

ip-address

—The virtual IP address of the hot standby router interface. You must enter the virtual IP address for at least one of the interfaces; it can be learned on the other interfaces.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.1_12c_ea1/configuration/guide/swhsrp.html#wp1044177

HTH

Regards

Inayath

*Plz rate all usefull posts.

[Sandeep Sharma]

Hi Taheq

We cannot use different address which is not in same subnet of the interface. And the reason is that it will be logically incorrect beacuse if you understand the need of HSRP : HSRP provides you a logical gateway (Logical IP address) and HSRP active router as candidate for that logical gateway to provide redundancy in case your hardware goes down.

so just ask a question from yourself can a gateway IP address of your network can be a different IP. No never.

----Hope this give you clarity

Thanks & Regards

Sandeep

[mfurnival]

Nah, never going to work. All needs to be on the same subnet.

By the way what does this line mean?

standby 2 follow instructions

[Jose Jara]

Yes, it is possible if you add an IP address as secondary and then configure the virtual IP of the HSRP in the same range as the secondary, for example:

interface FastEthernet1/0

ip address 80.1.1.1 255.255.255.0 secondary

ip address 192.168.1.1 255.255.255.0

standby 1 ip 80.1.1.10

Best Regards,

Jose.

[Bilal Nawaz]

Yes, But you are still eating/ "burning" in to address space here.

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

[Richard Burts]

The suggestion by Jose shows creative thinking but it is flawed. It would require 1 secondary addressin the public subnet on the first router, one secondary address in the public subnet for the virtual interface, and one secondary address in the public subnet for the second router. This uses three addresses in the public subnet. The original question was about trying to use only a single address in the public subnet.

As others have said so well - it does not work to try to configure the virtual address in a subnet different from the router physical interface address.

HTH

Rick