[e2e] Since we're already learning TCP fundamentals...

Bob Braden braden at ISI.EDU
Sun Mar 12 19:50:25 PST 2006

You are confusing a segment with a record.  You meant to ask,
why doesn't TCP count records?  (A segment is just another
name for a TCP packet; the sender is free to packetize any way it
pleases, so the count of segments has no significance.)

One simple answer to counting records is: because
if you count records, the protocol has to negotiate record sizes.
That is an extra mechanism.

Bob Braden

At 10:32 PM 3/10/2006 +0100, Michael Welzl wrote:
>... here's a stupid question:
>Why does TCP count bytes and not segments?
>Bytestream semantics, I know - but what's the benefit? TCP is
>not supposed to receive half a segment AFAIK, and counting
>segments = less space, or less risk of wrapping.
>There must have been a reason for this design choice.
>I expected to find an explanation in RFC 793, but I couldn't
>find anything - might have overlooked it though...

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