Date: Wed, 11 Feb 2004 14:50:49 +0100 From: Andre Oppermann <andre@freebsd.org> To: richard@wendland.org.uk Cc: freebsd-net@freebsd.org Subject: Re: dummynet = local taffic > 100ms - help! Message-ID: <402A3339.1BAAF97F@freebsd.org> References: <200402111335.NAA09040@starburst.demon.co.uk>
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Richard Wendland wrote: > > > 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. I remember some comments (by BDE?) to the effect that the patch is not entirely correct. -- Andre
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