Date: Wed, 11 Feb 2004 13:35:17 +0000 (GMT) From: Richard Wendland <richard@starburst.demon.co.uk> To: silby@silby.com (Mike Silbersack) Cc: freebsd-net@freebsd.org Subject: Re: dummynet = local taffic > 100ms - help! Message-ID: <200402111335.NAA09040@starburst.demon.co.uk> In-Reply-To: <20040211025940.J1798@odysseus.silby.com> from "Mike Silbersack" at Feb 11, 2004 03:01:25 AM
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> It breaks TCP Timestamp generation slightly, but that's not likely to > break much of anything in practice. Well, with HZ=10000 RFC1323 TCP connections will stop after 59.7 hours, with HZ=100000 after 6 hours. For those with long running TCP connections (eg remote backup) that could be a big deal. See 4.2.3 of RFC1323. It does seem quite a few people want HZ>1000 so I think the time has come to isolate the TCP timestamp option clock from the HZ value to avoid this problem. For now they should set net.inet.tcp.rfc1323=0 to avoid breaking RFC1323. Note this doesn't affect routed packets, only TCP connections to/from that host. Tom Pavel sent some patches to this list on 14 Jan 2004 that he has been using to overcome this HZ/RFC1323 problem. Richard -- Richard Wendland richard@wendland.org.uk
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