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New Member

Layer 3 Access Design


We are in the process of implementing a new network at one of our locations. We have purchased 2 6509s w SUP 720 to act as Core/Dist and for access layer, we have purchased 6 6509 w SUP 32. All the uplinks will be 10 Gig from Access.

We are thinking that we should do Layer 3 at Access and the proposed design is attached.

I have some questions/concerns listed below and wanted to get some feedback from this group.

1. Is this a good design and will it work.

2. We have not worked on Layer 3 at access so any best practices documents anyone can recommend. Any gotchas that we should be worried about.

3. What is the best practice for management IPs in the layer 3 design. In layer 2, we used to have all management IPs in one vlan but ofcourse this does not work well in Layer 3.

4. I am thinking that I will reserve 4 class Cs per IDF closet so that we can meet any future requirements. Any recommendations.

5. Any implications of NAC or other technologies that may not work with layer 3 design. I know of Wireless with Autonomous APs and we are implementing Lightweight Architecure. So I don't think we will have issue there.


Super Bronze

Re: Layer 3 Access Design

Should work.

Why L2 between cores and not L3?

Instead of 4 class Cs per IDF, you might want to reserve a /22 address block.

You can place the management IP into its own routed subnet.

New Member

Re: Layer 3 Access Design

Thanks for your reply. We are planning to do L2 between Cores as we will have Servers dually connected to each core/Dist switch. If one Switch Fails, we would still like the servers to function. In the future, we may get server farm switches and that point make Core L3 only.



Re: Layer 3 Access Design

Yes, routed access is a good design and it works. However, you need to get familiar with the design caveates and best practices. Before you deploy a routed access design you must read this:

Read this about how to deploy NAC in a routed access design:



New Member

Re: Layer 3 Access Design


Thanks for these links. They are very helpful.

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