Date: Thu, 20 Feb 1997 10:31:53 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: msmith@atrad.adelaide.edu.au (Michael Smith) Cc: terry@lambert.org, msmith@atrad.adelaide.edu.au, hackers@FreeBSD.ORG Subject: Re: sbwait hang? Message-ID: <199702201731.KAA15469@phaeton.artisoft.com> In-Reply-To: <199702200206.MAA14275@genesis.atrad.adelaide.edu.au> from "Michael Smith" at Feb 20, 97 12:36:45 pm
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> > This was recently discussed on -current, but the file was on a Linux > > box. Make sure TCP extensions are off on both ends; you probably have > > broken hardware somewhere in between which is lighting all the bits. > > The file is on BSD box 1. BSD box 1 has a modem on a serial port. > BSD box 2 has another mode on a serial port. BSD box 2 dials BSD box > 1, connects via SLIP. BSD box 2 attempts to transfer the File Of > Death from BSD box 1. Note that the file can come from systems > further away (BSD box 1 is a router), the transfer will still fail. > > Other traffic, including larger files, moves fine. This file stops after > about 4M. Your modem is looking for in-band data. The file is (unfortunately) providing it. I guess the next question is whether or not the modem is looking on purpose, or by accident, or as a result of a defect. What flavors are the modems? Is the receiving modem a US Robotics Courier/14.4 FaxModem, and the sender a modem utilizing the Rockwell modem chipset? If so, swap the modems. If the problem goes away, your US Robotics needs a firmware update. If one modem is an older modem with MNP (trellis encoding) turned on, but is not a older MNP modem manufactured by Multitech, then it is probably in violation of the MNP4 specification, and has enabled in-band flow control whenever MNP is enabled in lieu of providing sufficient buffer memory on board the modem, in order to underprice the Multitech offerings (the initial non-Multitech MNP modems did this as standard practice). If the modems are Telebit Trailblazer's, Trailblazer+'s, or you are going through a NetBlazer, then you should make sure "spoofing" is disabled. The older spoofing fails in the face of more recent additions to the SLIP standard. You should also check the status of S register 53 to make sure it is set correctly. If you don't have specific knowledge of the hardware, the first step would be to swap the modems, and go from there, to see if the problem is unidirectional (in the host or in the client software), or if it is that one of the modems can't transmit (or the other cannot recieve) the particular byte stream. Good luck; I'm afraid you'll need it... Regards, Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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