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Cisco core switching sizing and design recommendations

I'm trying to get design guidance for appropriately sizing core switches for new customer deployments.  I want someone go through the thought process and math involved in finding the "best fit" recommendation for a new core, based on industry "best practices."  

Let's use the following customer requirements as an example:

- Single campus with 500 total hosts (300 PC's, 200 of them connected through IP phones)
- Gigabit Ethernet access switches, spread across 5 access-closets (100 devices per closet)
- Dual fiber optic (MMF) connectivity between the closets and the core

We're going to go with a redundant core design, and the options are:

- Dual Catalyst 6506's
- Dual Catalyst 4506's
- 3750-X stack

(Please disregard the VSS capability of the 6500's - I want design and sizing guidance based only on port density, bandwidth requirements and oversubscription best practices.)

Explain the process of choosing the appropriate solution, as well as the recommended supervisor if choosing a chassis-based solution.

Thank you!

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Tory WCommented:
Best practices for your network design should be based not only on what you currently have to support, but on the projected, average and maximum growth for the network.  This is something you will have to sit down with your customer and line out.  (This needs to include any building projects coming up and any department adds, also overall growth of the customer's employee/ student base) (you will also want to compare this with the average growth of the industry your customer resides in)

There are no cut and dry numbers to use on this, but I would estimate out 5 to 7 years, so you have a good picture of what is to come.  

So, taking into account the future growth and the standard build-out for redundant links to 5 separate access-closets I would stay away from 3750s as your core devices.  

The main difference between the 4500 and 6500 series is the Supervisor cards and the software each of them support.  This will come down to what you are planning on running on each so I would check out the product data sheets and these videos to assist  you in making that decision.  

While the 4500 can be used as your core device, Cisco considers the 6500 series and 7000 series as core devices.  

Hope this helps.

6500 Video
4500 Video
cfan73Author Commented:
Thanks for the input, and I realize that projected growth should always be considered.  I'm also pretty familiar with the different supervisor options for the 6500 and 4500 chassis.  What I'm looking for here is a pretty focused exercise in determining a suitable core based only on bandwidth and port density requirements.  Let's assume that the numbers I've provided are growth numbers, and that we need to dictate a suitable core recommendation based only on these.

Tory WCommented:
So in a nutshell 6500 has more capability and based on what supervisor cards you use will be able to push more Gigs than the 4500.

I would give you specific numbers but they are all different based on your build out.  These two pages have all of those specifics for you though: 6500 specs  4500 specs

As far as port density the 6500 can handle XENPAKs, and has a wider array of cards that can be used as well as more core based software that is available, as far as acutal space and number of cards they both have 6 slots available.  

4500 can support 225 mpps forwarding

6500 can support 400 mpps forwarding

Really the trade-off is monetary.  If you have the money get the 6500, if not the 4500 will work for this application and be cheaper, but you wont have the performance.  

Hope this helps.
cfan73Author Commented:
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