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Fibre Connection

We have recently obtained a IGB Fibre Link from Colt and we are connecting it straight to the IGB interface on a 2950-24.

The IGB link is presented t us as SC and the IGB interface on the Switch is MTRJ. So I have used a SC-MTRJ fibre to do the connection. The connection does not come up on the 2950-24.

Even though Colt has been in several times to prove that there is traffic coming out of their equipment, I just don't get the IGB link come up on the 2950-24. The IGB interface on the 2950 is ok as I have connected it to another IGB interface and it came up ok but only when we connect the IGB fibre, it just does not work. Doing a loopback at both ends is also ok.

What can be wrong?

Thanks for your help


Re: Fibre Connection

Have you put a cross in one end (TX -> RX), standard MTRJ to SC patch cables are straight through, if you used them at both ends you would have patched RX to RX and Tx to TX, you need to use a special Cross Over MTRJ to SC cable at one end to get TX -> RX

Community Member

Re: Fibre Connection


As the other end of the fibre cable is SC and there are 2 of them. I toggled them to get the TX/RX.

So when you say special cross over, does toggling the SC interface give the same effect.

Also i read some wavelength level for fibres on the Cisco Website -

Optical transmitter 1300

optical receiver sensibility -14 dBm2

optical transmitter power -19 to -14 dBm

transmit -19 to -14dBm

But it was specified for the 2950C-24, can it also apply to the SX specification for 2950?



Re: Fibre Connection

MT-RJ is an SX interface and uses multimode fiber. Is the fiber from Colt multimode or single mode? How long is the run? Multimode can go about 900 feet. If its single mode you need LX interfaces (GBIC required so you need a different 2900). If its multimode but farther than 900 feet you need LX interfaces with a conditioning cable to make them work on MMF.

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