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New Member

cascading catalyst 3560

I am in the process of cascading several 3560 switches together back to our 6500 core, and want the traffic to flow "up", rather than allowing spanning tree to choose the bottom switch to go "down" back to our core. I have modified both path cost and priority, albeit not together, and have yet to get the "bottom Gig0/2" interface to go into blocking. Below is a graph of how traffic currently flows:

Core-Switch-01<--- 3560-A<---3560-B---- 3560-C--->Core-Switch-02

I would like traffic to flow this way:

Core-Switch-01<---3560-A<---3560-B<--- 3560-C---Core-Switch-02, using the link between 3560-C and Core-Switch-02 to transition from blocking into forwarding if one of the other links going 'up'


All connections are gigabit fiber trunks. Any suggestions are greatly appreciated on how to achieve my preferred traffic flow.


Re: cascading catalyst 3560

The current best practice per Cisco when doing this is to leverage the eigrp stub routing in the latest of switch software for faster convergence. This is now a feature of standard images.


New Member

Re: cascading catalyst 3560

I assume when you mean routing, you say layer 3. This is all layer 2, using the spanning tree protocol.

Also, convergence is not my primary objective. I want to get all the traffic flowing the same direction back to the core, instead of allowing the switches to pick the best route. Even though from Switch 3560-C the best route is to go 'down' back to the Core, I want traffic initially to flow through switches A and B.

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