Re: [ns] ECN!!!

[Sally Floyd <floyd@aciri.org>]

> thanks for the reply.Can you please let me know if the two way tcp
>supports ECN??according to the ns manual,no validations have been done for
>this.I am using a tcp-full.

There is a validation test for ecn with two-way TCP, "./test-all-ecn-full",
but it is not yet finished, and has not been added to the main
validation test suite, because two-way TCP does not yet pass it
correctly.  In particular, the test ecn_timeout_reno_full fails,
because with two-way TCP, the congestion window is reduced twice
when ECN is followed, in the same window of data, by a retransmit
timeout.

The test ecn_smallwinEcn_reno_full also fails, because two-way
TCP does not respond correctly to ECN when the congestion window
consists of only one packet.  This is described in the cvs log for
the file test-suite-ecn-full.tcl, at
"http://www.isi.edu/cgi-bin/nsnam/cvsweb/ns-2/tcl/test/test-suite-ecn-full.tcl".

If anyone wanted to make the appropriate changes to the two-way 
TCP implementation, I would be happy to check the changes into NS.

- Sally
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http://www.aciri.org/floyd/
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