Can I connect SINGLE MODE SFP (GLC-LH-SM=) to MULTIMODE fiber which has ST connector on Patch Panel side

[SP2]

Can I connect SINGLE MODE SFP (GLC-LH-SM=) to MULTIMODE fiber patch cord which has ST connector on the other side (Patch Panel). What is the loss for this set up ?

[Tom Randstrom · Accepted solution]

The short answer is yes.

The SFP data sheet outlines link length of up to 550mtrs on multimode fiber.  You will need to use a Mode Conditioning Patch Cord (MCPC) if your installed MMF is OM1 or OM2 rated, 62.5 micron or 50 micron core (use standard MMF patch cord if your installed fiber is OM3/OM4. You can purchase MCPCs with hybrid connectors; LC on one end and ST on the other; available at many reputable suppliers.  My link to a hybrid MCPC is for a 62.5 micron MMF.

I hope this helps.   

[walter baziuk]

the correct answer is NO

SM and MM are physically different
the connecters do not care about Sm or MM or speed(typically). they are simply standard means to carry and connect the single. common inplant fibre connecters are:

• ST is very old,
  
• MTRJ, typically only used in 100 mb/s system and by the military, never really caught on
  
• SC was common for a while, but was a bit bulky, was used in GBIC modules
  
• LC is the common standard now and is used for 1g, and 1gbs links. is the only type used in SFP
  

to connect a SM line to a MM line requires some form of media conversions
options include:

1. a layer 1 media converter. they are typically made with two ends. the ends can be copper or fibre (sm or MM) you buy the converter to meet your needs ie 1G CU Rj45 to 1 Gb/s MM fibre or
   in your case 1 Gb/s MM  fibre to 1 Gb/s SM  fibre
   they can be ordered as single units or get a chassis that holds around a dozen. the chassis simply provides a means to hold them and a common power supply
   
2. a layer two switch that accepts SFP modules
   simply place an SM sfp in one position and and a MM sfp in another position. then create a vlan between them.
   With a switch , you can also add a span port to monitor the traffic. This option cost more that option 1 , but works well especially if you can't get a media converter quickly
   

[Leo Laohoo]

I'll agree with Tom here.  It can be done if you use a mode-conditioning patch cord.

[Marvin Rhoads]

Seconding Tom's correct answer.

Note the OP is aksing about moving the signal from a SM transceiver (emitting coherent laser-generated light) across MM fiber (optimized for incoherent LED-generated signals). As Tom notes it will work (given use of a MCPC on OM1 or OM2 fiber).

You give up some of the distance you would normally expect when using SM end-to-end but it will work if you take the specifications and tolerances into account.

[SP2]

Thanks all for your comments. The situation now I have is little compicated. Our switches have SFP-LH-SM (LC connector- SINGLE MODE FIBER) on them for which we have LC-SC Mode Conditioning patch cords(CAB-MCP-LC) to connect to my MMF cable plant. But the fibre patch panels are old ones and have ST connectors on them. I don't have budget to buy more MCPCs with LC-ST type connectors. So I researched and found that there is some sought of connector/converter/plug which can connect SC connector of my MCPCs to ST connector on existing fibre patch panel. Is it true, are you guys aware of this type of connector/converter/plug ? Please help...

Thanks in advance!

[walter baziuk]

sc to ST is not common.

find a local supplier of patch cables and see if they can make it. as long as they can do those two types of connectors, they can make a custome cable. it might not be cherap though

[Tom Randstrom]

Yes, there are fiber optic bulkhead adapters to would allow you to connect a ST connector to SC connector.  The link below is to such a product. 

http://www.l-com.com/productfamily.aspx?id=531

Good luck!