Campus Design Question

[mjensen323]

Hello,

I've been researching some campus design documents the last few weeks. Attached is the layout to an 8 building campus I am working on. Each building would have a stack of 3750-X (1-2) with 1-2 2960S switches. All running 10 Gig links internally and between each building. The buildings are pretty small but are pretty high density. There are between 30-100 AP's per building, and 250-2000 devices per building. The datacenter would house 2 - 4500-x switches in VSS mode for the distribution layer. The core already exists with 2 - 3750-x switches connected to nexus 6248's to the blade chassis. I may just connect the 6248's directly to the 4500 in a collapsed core, but I may leave them separate to allow the traffic to stay separate.

The question is would you break apart each building in their own network and setup OSPF areas between each building? Or would it be one big Area 0? I'm trying to work out licensing and the best way to create speed / efficiency. There are no local resources inside the buildings. All the users are wireless and all the traffic will come back to the datacenter. The ISP is terminated in the datacenter for all the buildings as well. We also have utilize Cisco VOIP back at the datacenter.

Thanks in advance.

[Jon Marshall]

Firstly I'm assuming buildings 1 - 4 are chained due to cabling because obviously that is not great in terms of redundancy if for example building 4 went and took out 1 - 3 with it. Assuming it is cabling then if you were to use multiple areas you couldn't put each of those buildings (1 - 4) into it's own area because each area needs a direct connection to the backbone area.

So it's really a question like you say of using one big area or one area per building with the above proviso.

Personally I would use areas simply because if everything needs to go back to the DC and there are no local resources then it seems inefficient to me to have to propagate the LSAs for every network across the entire campus. Not only is this unnecessary in your setup but it is also an overhead the network and network devices simply don't need.

So I would put buildings 1 - 4 into an area and then the rest of the buildings each have their own area. If you have planned the IP addressing so you can summarise from each building then you simply advertise these summary ranges to the DC.

And as all traffic has to go back to the DC you only need a default route to be injected per area as there is only one way in and out of each area.

That is the way I would approach it but I haven't done design for a while so I am sure there are other ways to do it and hopefully others may chime in :)

Jon