Re: [tsvwg] [Tsvwg] lookup time (was Re: WGLC for Port Randomization starts now (April 1st))

Mark Allman <mallman@icir.org> Mon, 15 June 2009 12:38 UTC

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From: Mark Allman <mallman@icir.org>
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Cc: Alfred Hönes <ah@tr-sys.de>, "James M. Polk" <jmpolk@cisco.com>, tsvwg <tsvwg@ietf.org>
Subject: Re: [tsvwg] [Tsvwg] lookup time (was Re: WGLC for Port Randomization starts now (April 1st))
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> If you retry random port, chances are that you may retry the same port
> more than once, instead of trying a different port that might be
> available. The larger the number of ports in uses, the more likely
> this would be. (see the pseudo-code).

Sure.  Of course.  But, we can put this in concrete terms it would
seem.  I.e., if we use something like alg. 3 then for a given connection
ID we will not test for some port X again before exhausting all the
non-X ports.  In something like alg. 2 you can in fact check X more than
once with a probability defined by the port usage at the given time and
also not test for all possible ports.

allman