Connecting Fiber optics to Ethernet requires an Media converters

However, What i understood is Simplex fiber connection (only one single strand) is for one direction data transfer vs Duplex (dual strand) can be used in 2 way data transfer.

My question is: How come my fiber ISP router is connected using only one single strand ? While Internet is 2 way communication.

and will single strand fiber can communicate in both direction between 2 Media Converters ?


  • 1
    "Connecting Fiber optics to Ethernet requires an Media converters". No. Ethernet can use either copper or fiber optic as physical medium. We generally don't use media converter but transceiver (SFP, SFP+,QSFP...) in a switch to use ethernet over optical fiber.
    – JFL
    May 7, 2020 at 14:34
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    Ethernet is a family of protocols, and it can run over a variety of media depending on the specific ethernet variant. 10Base-T, 100Base-TX, 1000Base-T, 10,GBase-T are some that run over twisted-pair copper. There are also many variants that run over the various fiber grades over various distances. This answer lists a bunch of ethernet variants.
    – Ron Maupin
    May 7, 2020 at 15:19

1 Answer 1


Just like radio communications, where different systems can communicate simultaneously using different frequencies, simplex fiber optic communications also uses different frequencies of light (i.e., different colors).

In a simplistic example, the downlink to you uses red light, but the uplink to the ISP uses blue light.

Both colors of light can be carried on one fiber strand.


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