Date: Tue, 15 Oct 1996 08:27:52 +1000 (EST) From: "Daniel O'Callaghan" <danny@panda.hilink.com.au> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: question@FreeBSD.org, isp@FreeBSD.org Subject: Re: Modem latencies (was Re: ppp over vty possible ? ) Message-ID: <Pine.BSF.3.91.961015082148.2059K-100000@panda.hilink.com.au> In-Reply-To: <199610141650.RAA13959@labinfo.iet.unipi.it>
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I always was under the impression that the > 100 ms delay in a modem was because of the multiple stages of rs-232 the data must travel. e.g. computer-modem-modem-computer. Even the 16550 buffering into 10 byte blocks would probably have an effect. An empty 64 kbps ISDN link will give a rtt of about 20 ms, so I guess an empty "28.8 kbps ISDN" link would give about 60 ms rtt. Since there are three serial hops in the modem setup, an rtt of 180 ms is probably sort of reasonable. The above is strictly non-technical musing on my part - no basis in fact should be implied. (But factual arguments for and against are welcome) Danny
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