Date: Tue, 28 Jan 1997 11:36:05 -0800 From: David Greenman <dg@root.com> To: Petri Helenius <pete@sms.fi> Cc: hal@vailsys.com, hackers@freebsd.org Subject: Re: best mtu for lo0? Message-ID: <199701281936.LAA16507@root.com> In-Reply-To: Your message of "Tue, 28 Jan 1997 19:45:36 %2B0200." <199701281745.TAA25913@silver.sms.fi>
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> > Petri Helenius <pete@sms.fi> wrote: > > > > > What's your lo0 MTU? If it's the 16384 that some > > > non-tcp-knowledgeable person put in sometime in the past > > > I think what you are seeing is called "TCP deadlock" which appears when > > > window size is equal or smaller than the MTU. This makes TCP to be ... > > Is this correct? I notice 2.1.6-R sets MTU for lo0 to 16384. Should > > this be reduced to 1500? Will it affect performance of aliased IP > > addresses, for which a static route through lo0 is usually specified? > >Want me to comment on this (I'm not on the hackers list any longer >though)? > >The above still stands true that if you set your TCPWIN < MTU you'll >experience TCP 'deadlock' which ends up being of horrible performance. Pete is likely correct that window < MTU is a problem (that's obvious, right?), but he's wrong that this is occuring in recent versions of FreeBSD. The send/receive windows are set to 3*MTU, and for lo0 this is 49152 bytes. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project
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