Access Layer Routing

[Terence Lockette]

Hello everyone,

We're running on a collapsed core network design and I'm looking to move routing down to the access layer.  I've attached a sample diagram of a small portion of the overall network to give you an idea of how things are connected.  Currently, all routing, ACLs, multicast, etc. is being handled in the core.  I would like to move as much of this down to the access layer as possible.  The problem I'm faced with is our phone system (non-Cisco).  We have two PBXs that are not running in an HA configuration and are in their own VLANs with routing between them.  We have phones that are registered to both PBXs that are physically located throughout our campus.  I'm afraid that if I move routing down to the access layer, I'm gonna lose communications between the phones and the VoIP system since traditional routing won't allow me to have the same subnet in two different locations for the same infrastructure.  The only thing I can think of is possibly establishing EIGRP neighbors for the phone network and then NAT'ing the phones behind their gateway.  Can someone shed some light on some real-world workable solutions?

Thanks!

TLock

[Jon Marshall]

Just a quick follow up point.

If the number of new vlans is a worry you could get away with one new vlan per access switch. This assumes that your core switches are interconnected via L3.

You just use one new vlan on both the access switch and the core switches it connects to.

You would need three useable IPs because all three switches are sharing a common vlan.

The only "issue" with this is that the core switches would see each other via the access switch on that new vlan and would exchange routes.

However it shouldn't be an issue, as far as I can see, because the core switches are all interconnected with direct L3 links anyway so they should never see the access switch as the best path.

Personally I prefer the two vlan approach because it is more logical in terms of point to point links  and I think it would be easier to troubleshoot.

Just thought I'd mention it as it would cut down the number of new vlans you need.