G.655 fiber and GLC-LH-SM GLC-ZX-SM


I have a project which uses Cisco catalyst switch 2970 for two sites, connected by G.655 single mode fiber. Depending on the distance, I will be using either GLC-LH-SM or GLC-ZX-SM SFP transceiver module for my switch.

From Table 2 SFP Transceiver Module Cabling Specifications in the URL

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the SMF fiber recommended for GLC-LH-SM or GLC-ZX-SM is G.652.

However, the fiber will be G.655 instead of G.652 standard.

My question is whether there will be any issue using G.655 fiber for GLC-LH-SM or GLC-ZX-SM?

If not, assuming that I cannot change the fiber to G.652, is there any solution?

Thank you very much for any pointers and advice.

Best regards


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, the SMF fiber recommended for GLC-LH-SM or GLC-ZX-SM is G.652.

if you look at:

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it implies that the G.655 fibre is "better" quality - similar loss, and lower dispersion than base G.652.

the description here also implies G.652 is the baseline, and the other variaties mentioned are improved for various applications.

FWIW most of the issues mentioned are only a problem at higher speeds (say

10G), with DWDM, and /or long distances, so as long as you are not trying to push the limits on the kit you use you should be OK.

i think it will be OK - but you arent paying for formal professional opinions on Usenet........

go to whoever you are buying the cisco gear from and get them to issue an opinion (preferable backed by Cisco, and in writing).

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For the benefit of those who is following this thread, I just got reply from Cisco engineer, so I would like to share the knowledge with the group:

" Cisco does not certify the use of the G.655 fiber with Gigabit Ethernet. It does not mean that it would not work but the distance could be impaired. For example, if you use G.655 fiber with the

1000BaseLX/SX cable, its response would be like a multimode fiber instead of a singlemode fiber. The reason is that the G.655 standard specify that the cable cut-off is
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