Date: Tue, 17 Jul 2007 07:16:03 -0400 From: Randall Stewart <rrs@cisco.com> To: James Healy <jhealy@swin.edu.au>, Mark Allman <mallman@icir.org> Cc: freebsd-net@freebsd.org, Andrew <andybrand@swin.edu.au> Subject: Re: Odd congestion window behaviour [ was: Draft email to freebsd-net ] Message-ID: <469CA4F3.4080302@cisco.com> In-Reply-To: <469C27CB.9090906@swin.edu.au> References: <469AF916.6090901@swin.edu.au> <469AFE80.2090304@swin.edu.au> <469B5069.6080706@cisco.com> <469C27CB.9090906@swin.edu.au>
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James Healy wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > >>I.e. where we keep past connection state and use that >>as a reference for the initial cwnd. I asked Mark about >>this in the past.. and he said that his paper was >>mis-interpreted and this is incorrect behavior. If you >>have no connections up to a peer you should not use any >>past value for the cwnd... > > > So it's possible that the inital cwnd shouldn't be set by the hostcache > at all? > > If this was the case, does that mean we'd just use the rfc 3390 logic if > enabled, with fallback to the manual sysctl variables as a last resort? > IMO if you want to follow the true spirit of RFC3390 and RFC2581 then yes.. you should ONLY use RFC3390 (or 2581) to set your initial cwnd. I am adding Mark Allman on this to get his opinion.. Mark, here is your big chance to chime in on something that has had your name in comments in FreeBSD code for years... Basically let me referesh your memory in case you are not on net@freebsd.org (or you can go look at the thread). Currently FreeBSD will dig into its hostcache and set the cwnd of a new connection to the previous value with some constraints.. James posted these a fe days ago when noting funny behavior. I chimed in and said really IMO using the previous cwnd of old connections is NOT a good idea.. (I can see using the previous ssthresh.. but not cwnd).. and it is exactly why our SCTP implementation DOES NOT do this.. What do you think Mark (since your name is in the comments to justify this action).. R > James > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.7 (FreeBSD) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org > > iD8DBQFGnCfL4oawkrbYo/kRAuRMAJ47fESbkRB076y7w4hUA25FJp8i+wCcCg13 > aMQJpkHxjy6RdWXVoGmHhX4= > =QYKp > -----END PGP SIGNATURE----- > > Swinburne University of Technology > CRICOS Provider Code: 00111D > > NOTICE > This e-mail and any attachments are confidential and intended only for the use of the addressee. They may contain information that is privileged or protected by copyright. If you are not the intended recipient, any dissemination, distribution, printing, copying or use is strictly prohibited. The University does not warrant that this e-mail and any attachments are secure and there is also a risk that it may be corrupted in transmission. It is your responsibility to check any attachments for viruses or defects before opening them. If you have received this transmission in error, please contact us on +61 3 9214 8000 and delete it immediately from your system. We do not accept liability in connection with computer virus, data corruption, delay, interruption, unauthorised access or unauthorised amendment. > > Please consider the environment before printing this email. > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" > -- Randall Stewart NSSTG - Cisco Systems Inc. 803-345-0369 <or> 803-317-4952 (cell)
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