[e2e] bytes vs packets

Fernando Gont fernando at gont.com.ar
Mon Jul 28 13:27:31 PDT 2003


In the TCP section of David Clark's "The Design Philosophy of the DARPA 
Internet Protocols", he mentions three reasons for TCP acknowledging bytes 
rather than packets:

(1) Permit the insertion of control information into the sequence space of 
the bytes, so that control as well as data could be acknowledged.
(2) Permit a TCP packet to be broken up into smaller packets if necessary 
in order to fit through a net with a small packet size.
(3) Permit a number of small packets to be gathered together into one 
larger packet in the sending host if retransmission of data was necessary.

When he discusses the first reason (1), he states: "That use of the 
sequence space was dropped, in favor of ad hoc techniques for dealing with 
each control message."
Why does he say "it was dropped"? Control information (SYNs, FINs) *is* 
still included in the sequence space. Or does he refer to some other 
control information? If so, which one?

While discussing the third reason (3), he states "It was not clear if this 
advantage would be important; it turned out to be critical."
Wasn't any sending-side solution (such as Nagle's algorithm) considered at 
that time?


Fernando Gont
e-mail: fernando at gont.com.ar || fgont at acm.org

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