How many switches for a new building? Provisioning ideas...

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Jan 9th, 2008
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Hi all,

I've been asked to do up a budget for the network hardware (access and distribution layers) for a new building. I've never had to do this before so I was wondering how others have decided precisely how many switches they needed per floor?

I have manually counted, on the plan drawings, how many wall-plates are going to be installed on each floor (assume 3 jacks per wall-plate as per Aust. standard). I figured there are two ways to do this: either try and get an answer on precisely how many people are planned to occupy each floor (plus teaching spaces), OR see if there's a "standard" that exists that says something like "provide hardware to cover no less than two thirds of the installed jacks".

I'm really interested to hear how others have managed this task.



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Loading. Thu, 01/10/2008 - 04:17
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Distance, Density, Services, Power and Redundancy and are the things you need to consider.

A maximum of 300 feet per run for ethernet. Thats a combination of vertical and horizontal... cables very rarely run in a straight line from A to B due to building structure, wiring codes, and just random factors.

Where on each floor can you get power any what type ?

How many jacks per cube/office are being budgeted and do will they meet user expectations? (add in 20% fudge factor because its not good to be at 100% utilization day 1)

What services will the switch provide ? Any PoE ?

How redundant do the services need to be ? Multiple supervisors ?

ben_johnson Thu, 01/10/2008 - 14:43
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Distance - already accounted for in design

Density - Unknown at this stage (I'm assuming you mean how many people per floor)

Services - Data/VoIP

I've decided on the hardware spec (Cat3560 PoE) - it's just how many is the question.

"How many jacks per cube/office are being budgeted and do will they meet user expectations?" There's the $64m question. I'm providing the "this is how much it'll cost" factor - or attempting to at least - based on a best guess. Our organisation (University) doesn't have a standard for this type of situation yet, which is why I'm having to make it up.

There is power available at all locations where jacks are to be installed. Each wall-plate is a triple. Is it overkill to supply a budget based on a switchport for two thirds of all installed jacks?


PAUL TRIVINO Thu, 01/10/2008 - 16:03
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Just another viewpoint here:

First I'm not a big fan of the stackables/workgroup switches in (what sounds like) a big building. If you're doing VoIP I think the additional cost of a 45xx with redundant power supplies is worth it (no phones, no 911).

Second I'd say plan for ports 1.3 to 1.5 times wallplates/offices UNLESS this is an I.T. building/floor, the "average" user does fine with 1 port, a few will need 2.




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