I am new to networking, know about Ethernet and that Ethernet cables exist to make a wired networks. I also know about fiber optic cables which have a glass like material inside and transmit light signals instead of electrical ones. Now my question is, can I use fiber optic cables to for Ethernet or different type of implementation is made using fiber optic cables?

Thanks for your time!

  • 1
    Again, homework?
    – cpt_fink
    Commented Aug 5, 2018 at 4:36
  • 1
    "Ethernet and that Ethernet cables" You need to specify the type of ethernet cable. Ethernet runs on a variety of media: coax, UTP, STP, fiber, free-space laser, etc. Many people call UTP cables ethernet cables, but UTP can be used for other protocols, e.g. token ring, T1, POTS, etc. When you say ethernet cable, you must be specific to the particular medium you mean.
    – Ron Maupin
    Commented Aug 6, 2018 at 22:11

2 Answers 2


Ethernet uses a variety of cable types - an Ethernet cable can be pretty much anything. Ethernet has been using optical fiber for decades. The first standard was 10 Mbit/s FOIRL in 1987. The currently fastest PHYs run 400 Gbit/s. 800 Gbit/s and 1.6 Tbit/s started development in 2021. Fiber is actually the cable type with the most Ethernet variants by far, more than all others combined.

Fiber has become common in datacenters due to the frequency and reach limitations of twisted-pair copper - currently and probably permanently limited to 40 Gbit/s over only 30 m of category-8 twisted pair or just 10 Gbit/s over the full 100 m (of category 6A).

Depending on your requirements, you're probably looking for one of these:

  • 1000BASE-SX: 1 Gbit/s over up to 550 m of OM2 multi-mode fiber
  • 1000BASE-LX: 1 Gbit/s over up to 10 km of single-mode fiber
  • 10GBASE-SR: 10 Gbit/s over up to 400 m of OM4 MMF
  • 10GBASE-LR: 10 Gbit/s over up to 10 km of SMF

There are many other PHY standards for various data rates and distances, also many common non-standards for even longer distance. The required optical transceivers are usually SFP (1G) or SFP+ modules (10G) plugged into your network hardware. External media converters for devices without SFP slot are also available.

For a complete, up-to-date list of physical layer variants you can check WP.


Now my question is, can I use fiber optic cables to for Ethernet or different type of implementation is made using fiber optic cables?

Ethernet can be thought of as having multiple layers, exactly how many depends on who you ask and which variant of Ethernet you are talking about but we can divide it into four main parts.

  • Framing/filtering, encapsulating the higher level packets into an Ethernet frame with source and destination mac address and filtering packets based on those MAC addreses.
  • Serialisation and where nessacery medium access control, taking packets in memory and turning them into line-rate streams of data sent at the correct time.
  • Physical layer encoding, turning line rate data streams into electrical or optical signals suitable for the physical medium.
  • Physical medium, the actual wires or glass that carry the data.

The key is that as long as the first of these stays the same we can build a single consistent network, the end devices only need to know about the lower ones for their immediate link, they don't have to care about what they are on the rest of the network.

In some cases, external or pluggable transcievers are used, so the end device doesn't have to care about the last two points even for it's immediate connection. Those details are encapsulated in the transciever.

So yes the implementation details are different between Ethernet over Twisted pair and Ethernet over Fiber (and there are multiple variants of each) but it is still considered Ethernet.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.