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Design question - Fiber transceivers instead of Fiber switches

Hello All,

I have a simple design question. I have been asked to change a ring configuration to a star topology with a collapsed core/distribution layer.

The customer does not have the budget for fiber layer 3 switches so I am wondering if anyone has ever done this using fiber transceivers. Are there any gotchas or considerations I should keep in mind?

To be clear, I will give an example of one of the sites in question

There are 14 Wiring closets with a single switch in each closet.

The most central wiring closet is within 500 meters distance of 11 wiring closets (12 including itself of course)

The two remaining wiring closets are 600-700 meters away.

I was thinking of putting 2 X Cisco 3750x 48 port POE switches with 4 SFPs at the central location, configured using HSRP

Assume 2960 switches at all the remote locations.

I would have two fiber cables coming back from each remote location within 500 meters connecting into multimode transceivers at the core and split between the two core/distribution switches. At the remote side I would use standard multimode GBICs plugged directly into the switch.

The last two switches (the far ones) could be serviced in one of two ways

Single mode fiber back to the core using single mode GBICs both sides
Use multimode GBICs to bring them to the nearest two remote wiring closets. It's one extra hop but it would be a lot cheaper than using single mode fiber.


  1. I know it's not ideal but we have a budget to fit into. Will the above configuration work?
  2. Can you connect GLCSXMM fiber GBICs one end to a multimode transceiver the other end (which in turn uplinks to a gigabit port on the switch) ?
  3. Does anyone know the part number for the transceivers I should use? I prefer to use all Cisco equipment where possible.
  4. Has anyone every done it like this succesfully and what problems did you run into?

Many Thanks for taking the time to read this and any response would be appreciated.

paolo bevilacqua
Hall of Fame Master

You should use native fiber interfaces for all switches, not interface converters. There are also cisco-compatible brands for cost saving.