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Duplex mismatch using fibre to UTP transceiver with a 3524 & 5505

We have a situation where we are using several remote 3524 switches, which need to be connected to our core Switches (5505s)some distance away in another building. We have fibre links to and from these locations, but our 5505s only have 10BaseFL connections at present and their are no plans to upgrade these. In order to facilitate a 100Mbs connection back into the core switches, we have used a 100Mbs UTP to fibre Tranceiver at each end of the connection. These appear to be working correctly, but when I checked the error logs they were showing a duplex mismatch. I then tried every possible permutation of duplex and speed at each end of the connection, icluding auto at both ends. Eventually, using the auto at both ends the duplex negotiated at half.

Any suggestions as to what might be causing this??


Re: Duplex mismatch using fibre to UTP transceiver with a 3524 &

Let me see if I get this right the fiber on the 5500 is 10basefl and you are trying to get 100 meg out of the link ? Not going to happen , the most you can get out of those links will be 10 meg full duplex , that is all . If you look at the switches these will only be running 10 meg . You need to get 10 meg transcievers and then hardcode both ends to 10meg/fullduplex . You are going get all kinds of errors and performance issues trying to use 100 meg trancievers and is why you are getting the mismatches also . Can't force 100 meg down a 10 meg pipe . If I misunderstood you please post back and we'll take another shot at this .

New Member

Re: Duplex mismatch using fibre to UTP transceiver with a 3524 &

I think you missed the point! I am not using the 10BaseFL connections on the 5505, I am only using our internal fibre links to transport the data back and forth. These are transceived at each end back into UTP and connected to each switch. It appears that the transceivers are causing the problem, even though they are capable of running at 100Mbs and full duplex.

Hope this is clear!

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