troubleshooting Question

Question regarding GBIC on 3550 switches

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kam_uk asked on
6 Comments2 Solutions529 ViewsLast Modified:

I have just bought a 3550 Catalyst switch off ebay to play about with and learn from. The device has 24 FE ports and 2 GBIC ports for fibre. I'm confident regarding the configuration of L2/L3 switches, but have no real experience of fibre connectivity - it's always been there whenever I've had a job and never caused any problems ;)

Suppose I have an office of 100 users spread over 4 floors. Each floor has a 48-port Cisco 2960 switches for voice/data, but I'd also like some L3 switching, so I have the 3550. Where should this 3550 (and replace on of the 2960's) go ideally? On the bottom floor, with the servers, in the middle, or is it irrelevant? Each of the 2960's has a GBIC port for fibre connectivity with the adjacent floor(s).

On my 3550 there are two GBIC ports. Does each one correspond to one fibre cable (the equivalent of a 5e cable)? And how do they connect to the other switches? Will the top floor switch (switch A) have one GBIC port connected by fibre to one of the GBIC ports on the floor below (switch B)? And will the other GBIC port of switch B connected to one of the GBIC ports on switch C, and so on? If we want VLAN's, then obviously these ports must be set to trunk there any difference between configuring a 5e trunk and a fibre one? I'm thinking the media is irrelevant, but just want to be sure ;)

One final question, in a topology such as this, does the STP Root Bridge make a difference in regards to what switch it is? Should we manually configure the 3550, say, to be the Root for any reason? And any reasons against configuring PortFast on the user-connected ports?

Les Moore
Systems Architect
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