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Newbie question: Can I connect SX to LX GBIC?

ariesto.kosasih
Level 1
Level 1

If I have 2 switches within 5 meter distance... but one is LX and one is SX, will it work if I connect them both together?

Thank's in advance.

4 Replies 4

Prashanth Krishnappa
Cisco Employee
Cisco Employee

No you cannot mix GBICs on the same link

To be more specific, you cannot mix them because the optics operate at different wavelengths. SX GBICs operate at 850-nanometer, and LX/LH GBICs operate at 1300-nanometer. They won't "see" each other.

Also, I think there's a subtle difference in the way the GBICs put the light into the fiber: SX GBICs put it out off-set from the center of the fiber strand, in a way that generates multiple modes ("multimode"); LX/LH GBICs put it out down the center, so that there's a "single mode". When LX/LH GBICs are used with multimode fiber, they generally need a mode conditioning launch cable, that takes the single mode output of the LX/LH GBIC and steps it into the multimode fiber in such a way as to avoid flaws in the center of the multimode fiber strand, essentially "multimoding" it. Because the optical power is stronger, and because of the characteristics of the 1300-nm light, it lets you go farther on multimode fiber (550m) than the SX GBICs (220-275m).

Hope that helps.

Thank you very much.... now I learn something new! :)

It helps a lot!

-Ariesto

On the other hand, you can under certain circumstances use LX/LH and

ZX GBICs together. We have a link where this was used because *one*

of the original ZX GBICs was malfunctioning, and replacing it with an LX

just worked. LX at both ends could not be used due to length/loss budget.

(It is out of spec, and you can of course not count on *any* support for such

a mix of GBICs - thus definitely not recommended. But it's nice to know

that it can be done in a pinch.)

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