Proper SFP module for use

Answered Question
Jan 30th, 2012

Hello,

I have a 15' optical handoff run from our ISP Flashwave to a 3845.  We need an SFP capable of handling 1310nm single-mode transmission, but the GLC-EX-SMD has far more power than we'd need.  I'm thinking a lower-powered SFP that still meets the transmission criteria would be less expensive and wouldn't require a 5dB attenuator. 

I can't find another suitable option, can anyone suggest something different?  And if not, perhaps a link to optical attenuators that would work well with the GLC-EX-SMD?

Thanks in advance!

I have this problem too.
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Correct Answer by Marvin Rhoads about 2 years 2 months ago

You're welcome and thanks for the rating.

Actually Cisco refers to it both ways (1300 and 1310). Please see Table 4 in this document (and contrast with Table 1).

The GLC-LH-SM/D is very commonly used in just this application - metro Ethernet and service provider type of handoffs.

You may also want to take a look a the excellent document on this forum that Tom has put together. I keep it bookmarked.

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Average Rating: 5 (3 ratings)
Tom Randstrom Mon, 01/30/2012 - 18:02

It would be best to match the reach type (1000Base-??) of the optical interface of the connecting Flashwave interface card. I would check with the ISP to see if they can install a data card that accepts a short haul (SX) transceiver. 

A shorter reach 1310nm SFP compatible with the 3845 would be the 1000BASE-LX/LH, part number options include GLC-LH-SM & GLC-LH-SMD.

Marvin Rhoads Tue, 01/31/2012 - 07:05

Adding to Tom's recommendations, I always prefer to use the SMD models when dealing with 3rd party handoffs since they allow me to check the send and receive optical power levels remotely. They cost a bit more but if they save a couple trips to the data center, they more than pay for the delta.

j.england@alask... Tue, 01/31/2012 - 09:17

Thank you Tom and Marvin.  I've actually looked into the GLC-LH-SM/D, but the specs state that they're 1300nm SFPs... my lack of optical experience puts me at a disadvantage in that I don't know if this will work with the ISP's 1310nm handoff. 

Correct Answer
Marvin Rhoads Tue, 01/31/2012 - 09:45

You're welcome and thanks for the rating.

Actually Cisco refers to it both ways (1300 and 1310). Please see Table 4 in this document (and contrast with Table 1).

The GLC-LH-SM/D is very commonly used in just this application - metro Ethernet and service provider type of handoffs.

You may also want to take a look a the excellent document on this forum that Tom has put together. I keep it bookmarked.

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Posted January 30, 2012 at 3:40 PM
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