I was learning about the differences between TCP and UDP and I came across this rather inexplicable information on this page. It says:

Most users think of TCP and IP as a tightly knit pair, but TCP can be, and frequently is, used with other transport protocols.

For example, TCP or parts of it are used in the File Transfer Protocol (FTP) and the Simple Mail Transfer Protocol (SMTP), both of which do not use IP.


1 Answer 1


TCP and UDP are layer 4 (transport) protocols. They always use IP as the layer 3 (network) protocol.

The text you quote is just plain wrong.

You may notice that the page you reference was marked for cleanup. That should indicate that you should be suspicious of the accuracy.

  • 1
    I see the point that the book is trying to make, which is that there are setups where you can run TCP without an IP address, but that would be using a network design that is remarkably antiquated and you would probably only find in government and DoD networks. Commented Sep 6, 2016 at 14:09
  • @ZackScaringello how would it run without ip? Using the likes of MAC address I presume? Any little explanation would help.
    – Kraken
    Commented Sep 6, 2016 at 17:37
  • Flat layer 2 networks, hubs, and direct connections can use TCP without using IP addresses. Granted those are archaic networks and not one you are likely to ever encounter in the wild. Commented Sep 6, 2016 at 17:38
  • I would argue that the phrase "and frequently is," in the quote above is just wrong and misleading. There may be archaic and unusual cases of it (I'll have to take your word -- I've never seen it), but for all practical purposes, it doesn't exist. And for the networking student trying to understand the functions of layers, such oddball cases make things more confusing.
    – Ron Trunk
    Commented Sep 6, 2016 at 18:48

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.