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We have existing equipment that uses 100BASE-FX (multi-mode fiber). Will it work with 1000BASE-LX (also multi-mode) through autonegotiation? Virtually everything I found on the web about autonegotiation was for copper interefaces.

This question is different from this which covers the fiber.

EDIT: 2/8/11: changed gigabit to -LX so both are 1300 nm.

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up vote 2 down vote accepted

No, not by design, though it wouldn't be hard to design a NIC/module that could handle both but you'd need to let us know what equipment is at the gig end to allow us to help you on that.

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Some (unknown) proprietary equipment. My question is more about does the standard support autonegotiation? Require it? – Brian Carlton Feb 8 '11 at 21:14
No, the encoding is wildly different for a start. – Chopper3 Feb 8 '11 at 21:21
I think what Chopper means to say is that equipment that supports 1000BaseSX doesn't necessarily support 100BaseFX, it's possible the equipment supports both, but certainly not all cards do. – Chris S Feb 8 '11 at 21:32

The optical wavelengths of the two standards you mentioned, 100Base-FX and 1000Base-SX, are incompatible with each other.

100Base-FX uses a 1300 nm near-infrared (NIR) light wavelength, while 1000Base-SX uses a 770 to 860 nanometer, near infrared (NIR) light wavelength.

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