TCP fast retransmit

[Esztermann, Ansgar]

Hello list,

is there some documentation available on TCP fast retransmit? There seem to be quite a lot of descriptions -- from informal to scholarly papers -- on the various algorithms available to calculate the proper size of the congestion window, but I have been unable so far to find out *when* a fast retransmit is triggered. RFC 2581 states the third dupACK "should" do it, and this seems to be quoted fairly often. However, I can easily produce connections that fail to perform fast retransmit even after 5 dupACKs. Some people mention Linux uses a different (presumable more sophisticated) algorithm to trigger fast retransmits, but no-one seems to elaborate.


Thanks,

A.
-- 
Ansgar Esztermann
DV-Systemadministration
Max-Planck-Institut für biophysikalische Chemie, Abteilung 105

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