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1000BASE-SX to 100BASE-FX connection

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Jan 6th, 2006
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I want to uplink a new switch (Catalyst 3560 24 10/100 PoE + 2 SFP Standard Image)to an old switch which is 100BASE-FX using a MM fibre. Hence this is an issue of connecting a 1000BASE-SX port to a 100BASE-FX port using MM fibre. Can the connection work?

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spremkumar Fri, 01/06/2006 - 01:21
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AFAIK 1000BASE GBICs operate only on 1000M Fullduplex, we had tough time patching them up with a 100Mbps port earlier and found that its not compatible/work with different port speeds..


mheusinger Fri, 01/06/2006 - 01:27
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connecting two prots with different speeds can NOT work. The 1000BASE-SX operates on Multimode fibers, but that doesn´t help in case of a speed mismatch. AFAIK you cannot configure it to 100 Mbps.

Hope this helps


konigl Fri, 01/06/2006 - 11:24
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As the others have said, you can't connect 1000BASE-SX directly to 100BASE-FX.

If you want to connect to the old switch using 100BASE-FX, your best bet is to use a 100BASE-TX to 100BASE-FX Fast Ethernet media converter to adapt one of your 10/100 switch ports to the fiber. The copper side of the media converter plugs into one of your 24 10/100 switch ports, the fiber side plugs into the multimode fiber to your old switch. You will need an extra electrical outlet for the media converter's power pack, as it is an active networking component (needs power to work).

There are many manufacturers of Fast Ethenet TX-to-SX media converters out there. Personally, I recommend Transition Networks equipment, I've had good experiences with them. Their web site is:


If you decide to use a media converter, be sure to specify the optical side to be multimode, not single mode; the wavelength should be 1300nm for 100Base-FX (there are some short-haul versions that use 850nm, you probably want to avoid these); and match the optical connectors to the type of fiber patch cable you already have (SC is most common for 100FX, but you may have ST, or even LC or MT-RJ).

solomonthuo Mon, 01/09/2006 - 02:08
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INTERFACE CONVERTER ON GIGABIT SFP PORTS module which i think will solve the proble. I intend to plug the SFP on the 3560 gigabit SFP slots. for more details you can check the datasheet


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