10gig lx4 over smf

Unanswered Question
Oct 16th, 2009

Hello all, I have a 6509 with a few 3750E switches that I connect with 10gig-LX4 X2 modules. We have been connecting them with MMF. I have heard that you could also connect them with SMF. As a test, I connected one of the 3750's with SMF and it worked over a distance of 320 meters. I could not find this info any where on Cisco's site. Is this an unsupported cofiguration?

I have this problem too.
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viyuan700 Fri, 10/16/2009 - 06:20

10gig-LX4 X2 has a transmitter that can be used with both single mode and multi mode. I don't have a link from Cisco but check this link


When you use with FDDI grade MM and OM1 and OM2 fiber you need a Mode conditioning patch cord.

When you use over single mode you can get a distance of upto 10Km. Since your distance is only 320m, so check your power at both receiving ends and if more than -0.5dBm then use an attenuator. Else it can damage your receiver. See this link and read notes for LX4 since you are not using MCP mode conditioning patchchord you have to use an attenuator.


Tom Randstrom Fri, 10/16/2009 - 06:38

Cisco probably expects you would use an 10G-LR module on SMF instead of the 10G-LX4. Thus, their current documentation does not outline LX4 for SMF. It would technically be an unsupported configuration. You might be able to verify with Cisco TAC as maybe they have tested in this configuration and not published.

tjd2112pcca Fri, 10/16/2009 - 10:44

The 5-db attenuation talks about mmf without an MCP cable. The LX4 notes says there is no saturation over single mode. Thanks for the info!

viyuan700 Fri, 10/16/2009 - 11:55

I told you to be careful after going through the Max Trans power and Max Receive level as they were equal. I didnot read that whole info.But There is no harm in checking power level there are so many things which are written but works bit different.


But if somebody need info about LX4 on single mode can go through that page

"Please note the 10GBASE-LX4 devices can reach up to 10km over single-mode fiber as per compliance to IEEE."


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