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HSRP on sub-interface?


Will this enviroment work? I have 02 x Cat2950-24 and 02 x C3600.

The 2 switches is connect via EtherChannel and trunk. Each switch is also connected to both routers via trunking. The router ethernet interface is configure as a sub-interface. If I want to configure the two routers for HSRP. Can HSRP be configured at every sub-interface as i want every VLAN to be redundant.

I am on a tight budget so the Router sand the switches will act as my Core and distribution layer. Will this kind of network design works?



LS Ang


Re: HSRP on sub-interface?

It will work, with a decent IOS release on the routers. I would say 12.0 or higer. When I tell you it works, thats all it does. The 2950 is a workgroup switch and NOT a backbone switch. The 3600 series can handle quite a lot of traffic but this design is absolutely not ideal as a corporate backbone solution. Therefore you should not expect an outstanding performance.

A (dual) 3550 would do the job much better and it costs you less than the equipment you mention here.


Re: HSRP on sub-interface?

Ditto the above. Do not count on the routers for wire-speed Layer 3.

I have a central 6506 tying in eight sites over fiber, each site with three VLANs of its own. Primary Layer 3 servicing is handled by the 6506's MSFC2, with HSRP allowing the remote site's 2621 routers to go active only if fiber connectivity is interrupted back to the 6506.

In that fail-over situation, the local 2621's are configured with sub-interfaces for each VLAN and become the active router on each of those, so users can at least get from one VLAN to the next; not fast, but better than nothing. (The 2621's are there primarily for IP Telephony duty, as H.323 gateways. Next budget, I'm going to try to work in some 3550's for HSRP and dedicate the 2621's to H.323.)

New Member

Re: HSRP on sub-interface?

I personally would not use a 2950 Catalyst switch for any backbone routing/switching.The 2950 and the other lower catalyst series switches are best left as Access/Distibution layer switches at best to acheive optimum performance.

To configure HSRP at the sub-interface is a very good Idea, but I do not think it would be a successful one.Here is my reason:

1.I think it would be more beneficial to create fault-tolerance standby interfaces at the main interface layer because if the physical interface falls,the sub-interfaces fall with it, and all your configurations for HSRP on the sub-interfaces would go to waste.

My personal experience is if you create redundant links on the sub-interfaces, which one will be preempt? and if you have more than one sub-inteface as a preempt link they will contest each other, leaving your problem unsolved.

I think it would be a good idea to create a diagram and a pilot first and stress your idea on the chassis and document the changes in the IOS and present them to your superiors.

The proposed idea should not take longer than two hours to document and create your pilot.

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