> Lastly, if anybody already worked on this: do you have any additional > suggestion? In particular regarding the testing methodology: since a > few years have passed, I'm not quite sure whether different OSs have > implemented any countermeasure. I'm mainly testing against a FreeBSD > box I control, and I don't think we have any defence against this yet.
It would seem that some hosts are using byte counting to increase cwnd these days (that is, increasing cwnd based on the number of bytes ACKed and not the number of ACK packets that arrive). There are some measurements given in: Alberto Medina, Mark Allman, Sally Floyd. Measuring the Evolution of Transport Protocols in the Internet. ACM Computer Communication Review, 35(2), April 2005. http://www.icir.org/mallman/papers/tcp-evo-ccr2005.ps Also, I think there is wide community consensus that cwnd should be increased by min (number_of_bytes_acked, MSS) on each incoming ACK. RFC2581 is currently being revised and this will be the recommended way path in the revision (in 2581 it notes that an implementation may count bytes instead of packets). allman
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