Date: Wed, 24 Jul 2002 12:55:19 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: Danny Carroll <danny@legalaliens.org> Cc: net@freeBSD.org Subject: Re: Dummynet queues and one-pass Message-ID: <Pine.BSF.4.21.0207241251590.4594-100000@InterJet.elischer.org> In-Reply-To: <20020724192423.AAF3837B409@hub.freebsd.org>
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> Dummynet queues and one-pass: > I am just starting to look at Dummynet to try > and tune my ADSL connection. > My problem is that an upload from my end at full rate cripples the download. > I *thought* this was to do with ack packets not getting through but now I am > not so sure so I guess if there are any TCP/IP guru's out there, then > comments on this (common) issue are welcome. My copies of Internetworking > with TCP/IP Vols I, II, and III have been lent to a non-returner.... :( > > So. I have 1024Kbit down and 256Kbit up. > If I upload something, I get about 23-25KBytes/sec > If I Download something I get about 110KBytes / sec. > If I do both at the same time, the rates drop to 16 and 89 respectivly. > Actually the Upload xfer just stops and starts. This does look like your ack packets are being held up behind a large queue of incoming packets at the far end of the link. > > These tests were to an FTP server at my ISP with a 15MB binary file) > I left one_pass at 1 and added 4 rules to my ipfw. > add 10 pipe 1 tcp from any to [ftpserveraddress] tcpflags ack > add 20 pipe 1 tcp from [ftpserveraddress] to any tcpflags ack > add 30 pipe 2 tcp from any to [ftpserveraddress] tcpflags !ack > add 40 pipe 2 tcp from [ftpserveraddress] to any tcpflags !ack > > Then I configured both pipes to have 2048 bandwidth. (I do not want to > limit the flow..) > But looking at ipfw show, I noticed the ack rules (10 and 20) were the ones > matching most of the data and packets. > 30 and 40 were only matching a few. > So I didn't bother to configure the queues for giving priority to the ack > packets (which is what I *thought* I should do) because I didn't understand > what I was seeing. > If most packets are ack packets, what packets types are the ones that I need > to give more priority to so that my up/down connections will not stall? > Any comments? Nealy all tcp packets have ACK. They may just not be ACKing NEW data.. try limit you incoming data rate to 22KB/sec (select a rule that does NOT apply to the acks of the upload) The acks for the upload will slip in througn that 1K/S gap you leave them. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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