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New Member

HSRP:Layer 2 connectivity is required but in which way?


We have two multilayer switches and we are gonna make them work HSRP.

To my knowledge, Layer 2 connectivity between active router and standby router is required for HSRP. (For hello messages, etc)

Question: Does HSRP work properly if we supply this L2 connectivity by connecting two multilayer switches directly each other using their L2 ports?

Or do we have to use a third switch for this L2 connectivity?

PS: please do not concern about end users they have dual ethernet ports to connect to both L3 switches.

Thanks a lot for answering.


Re: HSRP:Layer 2 connectivity is required but in which way?


as you already stated, L2 connectivity is needed for HSRP to operate properly. How you achieve this is not so important - you can use a direct connection or a LAN switch between them.

From another point of view: your PCs need to be able to send to the active gateway with the same virtual MAC/IP regardless of which L3 sitch is the active one. So your PCs and both, active and standby router need to be in the same VLAN. This VLAN could still span many L2 switches.

In your case you would most likely setup a trunk between the L3 switches and attach the end users to the same VLAN in each switch. The trunk gives L2 connectivity mainly for proper HSRP operation.

Just make sure there are no SPT loops across your workstations and that they are setup properly.

Hope this helps! Please rate all posts.

Regards, Martin

New Member

Re: HSRP:Layer 2 connectivity is required but in which way?

Hi Martin

Thank you very much for making everything crystal clear once more. Luckly I have only one VLAN and all the computers belong to same subnet. It is a loop free topology since I am gonna connect PC's directly to Active and Standby L3 switches.

Re: HSRP:Layer 2 connectivity is required but in which way?

I do agree with above poster and as stated already that you need L2 connectivity for the proper operation of HSRP. You can have a direct connection between the multilayer switches or indirect connection via another L2 switches, it totally depends on the distance between the switches. It will work fine either way.


-amit singh

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