[Iccrg] Question on RFC 2988 - TCP Retransmission timer

[Ian McDonald]

After some discussion on the Linux networking list I thought I'd ask
the question here.

In RFC 2988 Section 2.4 says:
   (2.4) Whenever RTO is computed, if it is less than 1 second then the
         RTO SHOULD be rounded up to 1 second.

         Traditionally, TCP implementations use coarse grain clocks to
         measure the RTT and trigger the RTO, which imposes a large
         minimum value on the RTO.  Research suggests that a large
         minimum RTO is needed to keep TCP conservative and avoid
         spurious retransmissions [AP99].  Therefore, this
         specification requires a large minimum RTO as a conservative
         approach, while at the same time acknowledging that at some
         future point, research may show that a smaller minimum RTO is
         acceptable or superior.

Given that Linux, BSD etc use 200 milliseconds, not 1 second I am
wondering whether there has in fact been any research done as
mentioned in last sentence. It seems a very high timeout especially on
two locally connected devices.

Apologies if I'm asking on the wrong list.

Regards,

Ian
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