topic RE: Connecting a 100M switch to a 1G switch with fiber in Network Architecture & Design

Connecting a 100M switch to a 1G switch with fiber

Wayne1 — Thu, 14 Jul 2016 18:31:00 GMT

If you have one 100 meg switch and one gig switch does the fiber have to have converter so they can see each other. Is a converter required?
Had a splicer come in to repair fiber between two building one 100 meg and the other is a gig switch

RE: Connecting a 100M switch to a 1G switch with fiber

Drew_C — Thu, 14 Jul 2016 18:59:00 GMT

Hi Wayne, I've edited the title of this post for clarity.

As long as the 1G switch can negotiate down to 100M, you likely won't need to do any kind of conversion. Unless you're using something other than OM3 or OM4, you should be fine. You may need a mode-conditioning patch cord if you're mixing multi-mode and single-mode fiber.

RE: Connecting a 100M switch to a 1G switch with fiber

Nick_Yakimenko — Thu, 14 Jul 2016 19:00:00 GMT

Please provide correct models of both switches and models of SFP transceivers that you plan to use

RE: Connecting a 100M switch to a 1G switch with fiber

Erik_Auerswald — Thu, 14 Jul 2016 19:21:00 GMT

Hi Wayne,

in general, 100M over fiber is not compatible with 1G over fiber. There exist combined SFPs that support both 100BASE-FX and 1000BASE-SX, but they are not often used because they cost as much or more then one 100BASE-FX and one 1000BASE-SX transceiver together.

100BASE-FX uses the same fiber cables as 1000BASE-SX (multi-mode fiber, MMF). You cannot passively convert between different fiber types, you would need an active converter (e.g. a switch with both types of transceivers).

Best regards,
Erik