Multimode at 1Km

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Nov 6th, 2008
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I have a couple of 2950's I need to connect over a length of multimode fibre (50/125), my problem is that the total length is nearly 1Km. I'm aware that the maximum distance the cisco GBics etc and SFP's are a maximum of 550m - but I need more!!

Any suggestions would be greatly appreciated (expect change the fibre to single mode which I cant do!!!)

Many Thanks,


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e.claveau Thu, 11/06/2008 - 04:42
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I think what you're looking for is a multimode conditioning cable (CAB-GELX-625). Although you need LX/LH (singlemode) GBIC's for it to work.

mark.hall@dyfed... Thu, 11/06/2008 - 07:48
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Thanks for the response. I think I'll go for a media converter instead which will give me a 'guaranteed' service up to 2Km on multimode (alebit with a reduced throughput of 100Mbps which is fine for this application).

bbaillie Fri, 11/07/2008 - 19:59
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Well here is the pickle, an SFP is produced by a Cisco competitor that will do Gigabit over multimode for a max distance of 2 KM. If your switch is a 2950G then use the command "service unsupported-transceiver" ( this is a hidden command )on the switch reboot it and purchase a pair of AT-SPEX SFPs from Allied Telesyn they use LC connection like everybody else. They are very new, very cool, and nobody else to my knowledge can match them. Yup I have a pair and they do work, but you didn't hear it from me ;-).



bbaillie Sat, 11/08/2008 - 09:29
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OOPS, mybad, the 2950 series doesn't support SFPs, you will need a 2940-8TF or go to the 2960 series for the SFP support at minimum. I looked again and you are using 50/125 I tested on 62.5/125. Personally I would contact Allied Telesyn for a demo pair, but then again they are less than $450.00 American each so definitely worth the risk.



mark.hall@dyfed... Tue, 11/11/2008 - 01:03
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Hi Brian,

Many thanks for this info - certainly keep this handy info for the future.




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