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Valid reasons for having separte user switches and core switches

The cisco model defines separate switches for user connectivity and core switches for server and network connectivity. What reasons does cisco use to define these guidelines? What, if any are the 'cons' for putting users on core switches?

  • Other Network Infrastructure Subjects
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Re: Valid reasons for having separte user switches and core swit

Cost, redundancy and ease of cabling.

You need only run 1 or 2 connection from your core switches to your access switches in the IDF's and plug the PC's in there (instead of running cables from each PC to the core switches.

Ports on an access-switch are usually much cheaper than on a core-class switch.

In addition, if PC's are plugged into access switches (and each access switch is connected to 2 core switches) then you have reduncancy if you lose a core switch (If you lose an access switch, you still lose all of the machines on the access switch, but it should effect a much smaller number of machines).

Yes, you can plug uses into core switches, but you lose the redundancy. Core switches seem to go downmore than access switches (both the scheduled and unscheduled maintance!)

Re: Valid reasons for having separte user switches and core swit

I think a lot of this depends on the size of the network and how resilient you want it to be. If you have a small network of about 100 users and a few servers then it may seem logical to buy a high-port density switch such as a Catalyst 4000 and connect every device into it. The thing that comes to mind is 'Single point of failure' and all that - if you can live with it then fine. If you want to build in some redundancy then you need to start splitting the network up into Layers and employing Server Redundancy features. Cisco's classic design of Core, Distribution & Access, Intel's Server NIC Teaming, Microsoft's Clustering etc. This way if a failure occurs then it doesn't take out the whole network or all servers etc.

I suppose its entirely your choice at the end of the day and it depends on your budget and how much down-time you and your users can tolerate. I know customers who are quire happy to have the network down for a day or so while components are replaced and then there are others who insist on failover times of seconds.

A cheaply thrown-together network is fine until something breaks...........

When anyone mentions Plug & Play networking equipment I cringe - Plug & Pray it doesn't break......

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