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New Member

3750G and 2955C connected over MM Fiber?


I have a 3750G switch port cabled to a 2955C switch with multimode fiber. At the moment I have a SFP of type GLC-SX-MM in the SFP port on the 3750G.

The fiber port on the 2955C is labelled 100FX MM.

When I have the 2 connected over the fiber, I get no link LED on either end.

I suspect that the GLC-SX-MM (being Gigabit only) and the 100FX port are not able to communicate due to the speed difference. Is that correct? Do I need to replace the GLC-SX-MM with a GLC-FE-100FX to get link?

New Member

Re: 3750G and 2955C connected over MM Fiber?

Hi Charlie,

can you configure both the end for the speed of 100Mbps with "speed" interface command and check.



New Member

Re: 3750G and 2955C connected over MM Fiber?

Only the Copper SFP allows you to set the interface speed or to Auto-negotiate

The gig fiber SFP's support only Gig. I'm not sure if there are any Cisco SFP's that do 100 meg.


New Member

Re: 3750G and 2955C connected over MM Fiber?

Hello friend, remembers that single modules SFP GLC-SX-MM work on 1000mbps single in multiway and the fiber does not negotiate speeds, the only thing that you can make have a pair of equal modules in the ends or is GLC-FE-100X or GLC-SX-MM thus to be able to communicate them

note:both modules must handle he himself type of signaling MM or SM

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