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3550 eigrp and directly connected VLANs


We have just purchased a 3550 - EMI edition to support routing. I have configured 2 vlans on the switch and it has a fibre connection to the core. Without any routing configured on the 3550 traffic from vlan A to vlan B would travel up the fibre to the core switch (MSFC) get routed and travel back down the fibre.

Anyway, the objective of this switch is if the fibre breaks that the devices on both vlans can communicate with each other (they are both Cisco 3640 ISDN routers).

I have configured eigrp on the 3550 switch and configured passive-interface default so they don't send out any information (only listen). What I would like to do is if router on VLAN A needs to contact the router on VLAN B it would use the fibre back to the core first and if the fibre was disconnected/broken it would use route to the other vlan via the 3550.

Will just configuring eigrp and using passive-interface default work or do I need to some other configuration

I hope this makes sense



Re: 3550 eigrp and directly connected VLANs

No, it does not make sense. The most straightforward solution is to make the 3550 route between vlan A and B. There is no need to load the fiber with traffic that can be handled locally.

If you absolutely require the data to traverse the fiber, use HSRP and configure the 3550's interfaces to vlan A and B as backup for the core-routing engine.




Re: 3550 eigrp and directly connected VLANs

For one eigrp passive-interface default will not just "listen only".. ths will ensure that your 3550 never gets an adjacency on any interface with it's eigrp neighbors. Here's a link on the command:

Try, with your requirements, to alter metrics/ use distribution lists / etc to get the end results you are looking for.

Hope this helps,