From owner-freebsd-net Thu Sep 17 11:43:55 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id LAA00579 for freebsd-net-outgoing; Thu, 17 Sep 1998 11:43:55 -0700 (PDT) (envelope-from owner-freebsd-net@FreeBSD.ORG) Received: from pluto.cs.uah.edu (pluto.cs.uah.edu [146.229.2.78]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id LAA00539; Thu, 17 Sep 1998 11:43:33 -0700 (PDT) (envelope-from kkirby@pluto.cs.uah.edu) Received: from pluto (from pluto [146.229.2.78]) by pluto.cs.uah.edu (SMI-8.6/SMI-SVR4) id NAA24282; Thu, 17 Sep 1998 13:42:31 -0500 Date: Thu, 17 Sep 1998 13:42:31 -0500 (CDT) From: Kris Kirby Reply-To: Kris Kirby To: freebsd-questions@FreeBSD.ORG cc: Kevin Kyeong-il CHOI , FreeBSD Net Subject: Re: Why FreeBSD (or Solaris as well) get stuck in case of long delay ? In-Reply-To: <199809171437.HAA06002@implode.root.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > > 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 > I think it is worth noting that 200Kbytes/s is equal to 1.6 Mbit/s. And thus, 300Kbytes/s is equal to 2.4 Mbit/s. Does that even it out? Kris Kirby UAH Mail CS Home WWW ------------------------------------------- TGIFreeBSD... 'Nuff said. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message