I've heard the use of serial interfaces of router is not so common in the current network environment. But in some exams like CCNA, you can still see questions including the knowledge of serial interface. So, I don't know if it is true or not that using serial interfaces is not common.

  • 3
    Not common does not mean "non-existent". Almost everything is ethernet these days, but you'll still run across the rare T1, T3, and OC-x (as well as DOCSIS cable, xDSL, and cellular) interfaces. P-t-p microwave still exists, but it was always rare.
    – Ricky
    Commented Jun 20, 2019 at 1:23
  • 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 could post and accept your own answer.
    – Ron Maupin
    Commented Jan 4, 2023 at 20:12
  • Are you talking serial network interfaces or serial management interfaces? (the unqualified word "interface" in the context of routing usually refers to a network interface, but it can also refer to any kind of physical data connection or port) Commented Jan 6, 2023 at 0:21

3 Answers 3


As Ricky Beam has already written, even though Serial connections might not be common where you live, that doesn't mean they don't exist.

Over 90% of the connections we have in Europe use either Ethernet or xDSL. But in countries like Philippines, Nigeria and Cameroon, we have a lot of Serial connections.

In the end i guess it depends a lot upon where you are and what is available, that is also why Cisco have not ruled this type of connection out of their certifications. I do not know of any database specifying the most used connections based on which country you are located.


Serial interfaces are commonly used in my work as a Field Engineer. What you've heard is a misconception.


Long distance Ethernet has grown massively in popularity, because it is cheap, and because it means you don't have to deal with two different technologies for LAN and WAN.

However, building physical infrastructure has both significant economies of scale and significant regulatory implications. So, except for very short distances, it's rarely economical to do it yourself.

What that means is you ultimately have to deal with what the local communications provider(s) will sell you at a price you can afford. If the local communications network is still using oldschool telco equipment and standards then you will have to deal with that.

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