Core/Distribution/Access Layer Design

[conie saga]

Hello all,

We are in stage of deploying our network in three layers Core Distro Access

We have 2x6500 (VSS) on core, 3750 (with 10G interfaces) on distribution & 2960 (with 1G interfaces) on access.

I am confusing about the role of Distribution switch in environment ?

For example, For end users should i configure L3 interfaces on  Distritbution switch & trunks between distribution to core switch   & distribution to access layer switches ? Or layer 3 interfaces on  core & just trunks to distribution switch & from distribution to  access?

what should be the default gateway i need to configure on access switches ?

If it would be only core & access layer switches, then its easy for  me to design. All L3 on core & trunks to access layers. Core will  take care of intervlan.

can any body suggest how to design network having distribution switch in environment ?

[lmediavilla]

Depending of the number of networks and the big of the site you can just use core/distribution with the 6500 and access with the other switches, and keep the 3750 for the servers if you don't have port density on the 6500

this question is answered in here

https://supportforums.cisco.com/thread/2109822

kind regards

[devils_advocate]

For example, For end users should i configure L3 interfaces on  Distritbution switch & trunks between distribution to core switch   & distribution to access layer switches ? Or layer 3 interfaces on  core & just trunks to distribution switch & from distribution to  access?
what should be the default gateway i need to configure on access switches ?

Do you need a seperate core and distribution layer? Not everybody does but if the money is there to implement and in order to futureproof, perhaps you should. Lots of people just follow the Cisco guides for best practice and fund a seperate core/disto layer but don't always need it because they have not understood what benefits having them seperated will give.

Anyway.......

I would first off be looking to create a 'Management' VLAN in which all your access switches will have thier management addreses. Seperating management traffic from user traffic is best practice.

Your 3750 Distribution switches should be the default gateway for all your Host VLANS.

I would be using L3 links between the Core and Distribution layer and running a routing protocol between them such as EIGRP or OSPF.

Using your question as an assumption of your current technical knowledge on this subject, my recommendation would be to use L2 trunk links in a port channel arrangement between your Distribution and your Access Switches. One thing to consider here is resiliency and redundancy. Depending on your proposed topology, if you plan to have 2x 3750 stacks for your Distirubtion layer, you would need to run something like HSRP between them and Spanning Tree to control the redundant links.

The huge benefit of the VSS is that you don't need a first hop routing protocol like HSRP and Spanning Tree is also taken out of the mix, not to mention being able to use all available bandwidth.

As I sum this up, I am wondering if its worth considering using a collapsed core topology and use the 6500 in a VSS setup for this. Unless your network is going to be 'large', you may benefit from using a collapsed core because it means much more resiliency and redundancy between the Access and the Core/Dist Layer, plus you have double the bandwidth.

Hopefully this makes some sense...