Layer 3 Mesh networking

Can any one tell me how to do this?

Say i have 5 switchs, three distrubtion switchs with two core switchs

each distrbution switch has a link back to each core swith, and the core switchs are linked togather (via an etherchannel)

See digram.

now I want to set up EIGRP routing.

easy enough and I know two ways to do this.

Set up all the links as trunks, have a vlan on all the switchs with a ip address in the same subnet and use this to route the packets across.

this is ok apart from the fact that some links will be blocked by spanning tree, so data will not travle the most efficent path.

Second I could set up each switch to switch link as a point to point ip link.
This would mean data would be sent in a more efficent fassion as it would be routed down the most direct links.
But this means settign up 7 seperate IP links. (in my actuly case there would be a lot more as I have about 30 distrbution switchs)

Is there a way to do away with the IP address on the switch to switch link, while still keeping them as routed rather than switched interface?

I am sure this is possible but just not something I have set up or can find much info about.

Cheers

Oh i should mention all 3750 and above switchs

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Comments

networker050184

No there isn't really a way to do what you are asking without using all the point to point to point address space. Like you said you can use trunks and SVIs, but you will have to deal with STP. Are you strained for address space or something? I'm assuming this is your LAN so private addressing shouldn't be a concern. Putting in the routed links really is the best solution here.

DevilWAH

networker050184 wrote: »

No there isn't really a way to do what you are asking without using all the point to point to point address space. Like you said you can use trunks and SVIs, but you will have to deal with STP. Are you strained for address space or something? I'm assuming this is your LAN so private addressing shouldn't be a concern. Putting in the routed links really is the best solution here.

yep i thinking that the more i look at it,

the only other thing is the

#ip unnumberd command under the interface

setting up a vlan with an ipaddress, then settign both the uplink interface to share that ip address.

just need to test it out.

but thinking about it i may need to run some switched vlans over the links as well, so it might be worth running the links as layer 2 and jsut accept that some will be blocked by spanning tree.

networker050184

Ip unumbered should work for you, but I don't see why you would want to add the extra confusion in this situation. Do you not have the addresses available?

If you really need VLANs to span your distribution or core, I'd still go with SVIs to route between the switches. To avoid blocking of any of these you can just you a different VLAN for each point to point link. This VLAN will only exist between the two switches it is linking and therefore will never be blocked. Then only allow those certain VLANs that need to span and the one you are routing with on the inter switch trunks.

DevilWAH

networker050184 wrote: »

Ip unumbered should work for you, but I don't see why you would want to add the extra confusion in this situation. Do you not have the addresses available?

If you really need VLANs to span your distribution or core, I'd still go with SVIs to route between the switches. To avoid blocking of any of these you can just you a different VLAN for each point to point link. This VLAN will only exist between the two switches it is linking and therefore will never be blocked. Then only allow those certain VLANs that need to span and the one you are routing with on the inter switch trunks.

Oh actuly thats not a bad idea, and you only need to use two extra vlans. all distribution switchs use the same vlan for there primary link and a second for the back up link.

Simple cheers..

each distribution switch uses the same vlan as all the others for its

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