From owner-freebsd-net  Fri Sep 20 19:20:12 2002
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Date: Fri, 20 Sep 2002 19:19:03 -0700 (PDT)
From: Julian Elischer <julian@elischer.org>
To: Mike Silbersack <silby@silby.com>
Cc: net@freebsd.org
Subject: Re: Tcp question.
In-Reply-To: <20020920204805.G6326-100000@patrocles.silby.com>
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p.s. just for kicks I turned off newreno and set teh slowstart
flightsize up..
net.inet.tcp.local_slowstart_flightsize: 65535
net.inet.tcp.newreno: 0


no real difference.

On Fri, 20 Sep 2002, Mike Silbersack wrote:

> 
> On Fri, 20 Sep 2002, Julian Elischer wrote:
> 
> > OK so I have 3 machines:
> >
> >
> > A------router--------B-------router--------C
> >
> >
> > if I send data from B to A I see 7MB/sec.
> > if I send data from B to C I see 700KB/sec
> >
> > tcpdump shows some odd behaviour in the slow link:
> > (tcpdump run from (B))
> 
> Could you repost with more of the timestamp intact?  It's really hard to
> read as is.
> 
> > 000221 C.ssh > B.916: . [tcp sum ok] ack 66194 win 24624
> >   nop,nop,timestamp 259781842 16260556> (DF)
> >   (ttl 64, id 18252, len 52)
> > **why wait here**?
> > 003030 C.ssh > B.916: . [tcp sum ok] ack 68930 win 24624
> >   nop,nop,timestamp 259781842 16260556> (DF)
> >   (ttl 64, id 18253, len 52)
> > 000279 C.ssh > B.916: P 3769:3813(44) ack 70298 win 24624
> >   nop,nop,timestamp 259781842 16260556> (DF)
> >   (ttl 64, id 18254, len 96)
> 
> Hm, the TCP stack doesn't look like it thinks that it's waiting... the
> timestamps don't seem to be incrementing.  Of course, since I can't see
> the timestamp, I don't know what waiting means. :)
> 
> Have you tried disabling delayed acks just to be doubly sure that the
> delayed ack code isn't causing the problem somehow?
> 
> Also, is C really a FreeBSD box?  I didn't think we used window sizes
> of 24K.
> 
> Mike "Silby" Silbersack
> 
> 
> 
> 
> 
> 


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