2960 switch fiber connection over 40km single strand SM fiber

[mario_kmc]

Hello everyone,

We are having an issue with the connection in the subject. We just gost dark fiber for connecting 2 2960 switches with single strand single mode fiber over more than 10Km.

Looking at the compatibility matrix and the SFP gigabit applications the 1000BASE-BX10 is the best I could find but cannot reach more than 10Km.

Can anyone please propose a solution? If media converters are the only way to go can please sugest manufacturer/model (even with SC connector) since Cisco does not make Media converters.

Thank you

Mario

[Tom Randstrom]

Does your model 2960 switch support CWDM SFPs? 

If so, you could install a single fiber CWDM mux/demux at each end of your fiber link and order the appropriate wavelength CWDM SFPs at each end. This mux/demux has LC connectors, same as what is on the SFP module.  The CWDM SFP's have a 30dB loss budget, plenty of optical power to support 40km fiber and mux/demux losses (approx 2dB per end for 2 channel unit). 

[mario_kmc]

Hi Tom,

Thanks for your time. According to the compatibility matrix yes the 2960 do support CWDM SFP but a quick look does show they are quite expensive. The price would even worsen for adding the mux/demux. Its a good solution for a small aggregation site. We will look into it.

I'm not really an optical guru but when you say "30dB loss budget" does it mean you can have 30dB loss but still get good signal at the receiving end?

MP

[Tom Randstrom · Accepted solution]

A 40 km link is usually run using 1550nm wavelength due to lower light loss on the fiber at this wavelength.  The 1000BaseEX module is spec'd to 40km and runs at 1310 nm wavelength, but you will lose light through a WDM filter (which is integrated in the single fiber SFP) which would reduce the link's length.  I would check with some of the 3rd party media converter manufactures to see if any of them have a lower cost solution that operates over a single fiber at >40km. 

Sorry... a link loss budget is the sum of:

Fiber cable loss + fiber connector losses + fiber splice losses + impairment losses (dispersion or PMD) + aging losses (safety margin).

If the transceiver's Loss Budget is greater than the Link Loss Budget, then the link should operate. 

www.thefoa.org has some good videos for understanding fiber terminology at an easy to understand level.

[mario_kmc]

Tom,

Many thanks and sorry for all the time for feedback.

So everyone knows, we decided on a media converter with 1000Base-BX40 SFP solution. So used to checking only cisco SFP's didnt know there was 1000Base-BX40.

Thanks for the link I'll do my best to at least get the basics.

Regards

Mario