2

The MTU for 802.11 is 2296 bytes. Does this mean that if TCP is used over 802.11, the MSS can only be 2296 - 40 = 2256? Can't one use a higher MSS which would then get fragmented over 802.11?

In short, is there a strict limit on the MSS for TCP?

  • 1
    In practical terms, you are only going to get an MTU of 1500 on Wi-Fi because the traffic will probably need to traverse an ethernet network somewhere in the path. Your practical MTU is going to be the smallest MTU in the path. – Ron Maupin May 24 '17 at 18:18
  • Yes, but my question is whether a 'theoretical' MSS greater than 1500 is acceptable at the Transport Layer. – V-Red May 24 '17 at 18:23
  • 1
    Theoretically, your MSS can be 65,535 minus the TCP header size. In realistic terms, it is the MTU minus the IP and TCP header sizes. – Ron Maupin May 24 '17 at 18:25
  • 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 provide and accept your own answer. – Ron Maupin Feb 19 '18 at 5:48
2

Does this mean that if TCP is used over 802.11, the MSS can only be 2296 - 40 = 2256?

MSS = MTU - IP header size - TCP header size:

https://en.wikipedia.org/wiki/Maximum_segment_size

Can't one use a higher MSS which would then get fragmented over 802.11?

Most routers implement MSS adjust functionality. During TCP handshake the MSS get adjusted on each hop along the path to its minimum value. So the following TCP packets with data are fit into the MTUs along the path and packets do not get fragmented.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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