Date: Thu, 17 Sep 1998 07:37:48 -0700 From: David Greenman <dg@root.com> To: "Kevin Kyeong-il CHOI" <kevin.choi@cnes.fr> Cc: "FreeBSD Question" <freebsd-questions@FreeBSD.ORG>, "FreeBSD Net" <freebsd-net@FreeBSD.ORG>, tcp-over-satellite@achtung.sp.trw.com Subject: Re: Why FreeBSD (or Solaris as well) get stuck in case of long delay ? Message-ID: <199809171437.HAA06002@implode.root.com> In-Reply-To: Your message of "Thu, 17 Sep 1998 08:59:32 %2B0200." <006801bde208$b8e51ac0$52099584@pc-kichoi.cst.cnes.fr>
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> Capacity = RTT x Bandwidth. >and the capacity would be limited by the window size. > >Here, I used 64K for Window size (65536), so the Bandwidth >should be > > Bandwidth = Capacity (65536) / RTT > >I made the delay in one way as 200 ms, and RTT becomes 400 ms, so >the nominal Bandwidth becomes 1310720 bps = 1.3 Mbps. > >Curiously enough, between two Windows boxes, the maximum bandwidth >is obtained, which is about 1.0 ~ 1.1 Mbps. > >BUT, for FreeBSD, or for Solaris, I obtain only 200 ~ 300 kbps. >(precisely 200 kbps for Solaris, and 300 kbps for FreeBSD). FreeBSD is almost certainly still using a window of 16KB. There are problems in the code related to changing the socket buffer size after the system is up. You pretty much have to modify the default value in the kernel source files in order to use a larger window. -DG David Greenman Co-founder/Principal Architect, The FreeBSD Project To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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