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R PVST+ with GLBP

Hi guys,

Imagine that you have two layer 3 switches cat6500 in distribution layer acting as root bridges and gateways with EIGRP and GLBP. The access switches are cat4500 and are connected to both distribution switches. What is the best way to go:

link between the distribution swithes in layer 3 or layer 2? This will affect the spr blocked ports.

Is one device block the link from one side but from the other side the link is forwarding the traffic flows from the fwrd to the blocked side right?

I hope you uunderstand my question.

I want to know if GLBP is a better solution than HSRP with R PVST+ in this scenario.

Best regards!

1 REPLY

Re: R PVST+ with GLBP

Hi,

Ideally the link between distribution switches should be layer 2 trunk port carrying all the vlans in it.

The access switches-4500's will have redundant link to both the distribution switches.

You can alter spanning priorities suitably in the distribution switches, so that the link between the distribution switch will not get blocked. Rather one of the redundant link from the access switch to the distribution layer will be blocked.

It is quite natural that in Spanning tree only one end of the redundant link will be in blocked state. The other end will still be in forwarding state. There is no need to block both end of the links..

For your scenario, HSRP in distribution switches for intervlan routing will be the correct solution.

GLBP is used for different scenarios, where in you can provide redundancy and load sharing for the IP hosts in lan.

Refer to a sample GLBP topology and its usage here

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a008042fb97.html#wp1048174

Hope this helps. Please Rate the post if you find it usefull.

-VJ

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