According to some sources, SONET is physical layer.

But some sources say that SONET can carry IP directly. Also, SONET defines its own frame -- it has a header and a payload. That must make SONET a data link.

What is the truth about SONET? Also, where can you see SONET equipment and fiber optic lines?

  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer.
    – Ron Maupin
    Commented Dec 17, 2020 at 21:15

1 Answer 1


SONET defines a physical layer (or variants thereof) and a common data link layer, similar to Ethernet.

(Circuit-switching) SONET used to be a popular carrier technology but has largely been replaced by (packet-switching, much more efficient) Ethernet.

Your Answer

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

Not the answer you're looking for? Browse other questions tagged or ask your own question.