Date: Sat, 21 Jun 1997 20:41:17 -0400 From: "Louis A. Mamakos" <louie@TransSys.COM> To: Terry Lambert <terry@lambert.org> Cc: adam@veda.is, joerg_wunsch@uriah.heep.sax.de, freebsd-current@FreeBSD.ORG Subject: Re: getty modem control Message-ID: <199706220041.UAA25091@whizzo.TransSys.COM> In-Reply-To: Your message of "Sat, 21 Jun 1997 14:05:10 PDT." <199706212105.OAA27805@phaeton.artisoft.com> References: <199706212105.OAA27805@phaeton.artisoft.com>
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> You can't reliably run the computer-modem rate at a higher rate > that the modem-modem rate. Conversely, you can't reliably run > the modem-modem rate at a higher rate than the computer-modem > rate. That's news to me; I routinely ran a serial port at 38.4 kb/s with CTS/RTS hardware flow control with a V.32 (14.4kb/s) modem, and it worked just fine. As I was using it for SLIP, I knew there were no overruns because there were no IP, TCP or UDP checksum errors. > This is because of issues of bufferring, and when common UART > chips trigger interrupts relative to their FIFO size. I do not dispute broken hardware, but it's not all universally busted. > The last modem you could reliably run at differential speeds was > the original MNP Microcom modems; they had huge buffers. This was on a ZyXEL 1496 modem. > Link-level compression is evil anyway; compression belongs on > the host side of the host UART so that the datarate is not > limited by the serial port rate. I disagree. Given that the modem is already doing V.42 link-level reliablity, it fits in very nicely with it's segmentation. louie
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