Ian McDonald wrote:
Hmmm... RFC2988 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. I went and had a look and this RFC has not been obsoleted. RFC3390 also backs this assertion up. So I'm suspecting that the default should be changed to 1000 to match the RFC which would solve this issue. I note that the RFC is a SHOULD rather than a MUST. I had a quick look around and not sure why Linux overrides the RFC on this one.
If nothing else, 200 ms is a "principle of least surprise" thing since that is the current value (in MS) for TCP_RTO_MIN.
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