Date: Sun, 07 Jul 1996 18:47:26 -0700 From: David Greenman <davidg@root.com> To: Network Coordinator <nc@ai.net> Cc: freebsd-questions@freebsd.org Subject: Re: Increasing FTP thruput. Message-ID: <199607080147.SAA00690@root.com> In-Reply-To: Your message of "Sun, 07 Jul 1996 21:10:53 EDT." <Pine.BSF.3.91.960707205814.17361A-100000@aries.ai.net>
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>On one of our development machines we are running wu-ftpd. When FTP'ing >over a T-3 to a PPP (28.8kbaud) line from a PPro 200 to it we were seeing >as low as 2.0k/second. Yet, FTP'ing from a Sun 4/75 we were seeing >2.8kbaud solid performance. > >It appears to be [by watching modem lights] that the BSD box isn't >streaming in the sense of a continuous send or receive while receiving >acks along the way. The Sun boxes [all of them] seem to do this out of >the box. > >I verified this behavior on ftp.cdrom.com and random SunOS boxes. > >Any ideas how to make the BSD behavior more like the SunOS? Watching modem lights is an extremely poor way to do critical analysis. The SunOS machines send out ACKs every other packet and further restrict the window size to 4096 bytes. I'm really suprised that FreeBSD comes out worse in your test. If you're doing the tests using ftp.cdrom.com as the endpoint then you might be seeing the effects of asymetric lossage - especially since there are so many intermediate hops involved. I suggest looking for dropped packets in the netstat -s statistics. Oh, and you didn't mention which version of FreeBSD you're using or whether you're using the kernel PPP or usermode ijppp. You could be seeing the effects of one or more bugs in the PPP code. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project
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