Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!rutgers!seismo!ut-sally!utah-cs!cetron From: cetron@utah-cs.UUCP Newsgroups: comp.protocols.tcp-ip Subject: Re: 4.3 TCP keep-alive question Message-ID: <4509@utah-cs.UUCP> Date: Sat, 18-Apr-87 20:10:12 EST Article-I.D.: utah-cs.4509 Posted: Sat Apr 18 20:10:12 1987 Date-Received: Sun, 19-Apr-87 08:27:22 EST References: <8704182219.AA08621@okeeffe.Berkeley.EDU> Reply-To: cetron@cs.utah.edu.UUCP (Edward J Cetron) Distribution: world Organization: Center for Engineering Design, Univ of Utah Lines: 31 Keywords: Ultrix keepalives missing line of code Summary: Ultrix is missing a line of code In article <...> karels%okeeffe@UCBVAX.BERKELEY.EDU (Mike Karels) writes: ->Curiously, I tried an experiment with keepalives a few weeks ago. ->Your description of the comment in the 4.2 source isn't quite ->accurate; the comment accurately describes what the code does, ->but is wrong about the reasoning. Both 4.2 and 4.3 send -> ->with one byte of (imaginary) data. As you observed, sending -> ->with no data should be sufficient to elicit a response. However, ->although 4.3 systems and Sun 3.x systems responded to such probes, ->Ultrix 1.2 (and 2.0 field test) systems failed to respond, which ->rather annoyed the users whose windows would disappear after some ->minutes of inactivity. I haven't tested this with more systems After spending a week hacking keep-alives into the Tektronix TCP/IP code, I too was quite frustrated when many ultrix users kept calling and complaining about there windows disappearing. After much poring through both the 4.2/4.3 keep alive code and comparing it against the ultrix 1.2 code it became obvious that ONE SINGLE LINE OF CODE IS MISSING in the ultrix networking code. Seems it gets the keepalive, figures out it is a keep alive and then doesn't have that ONE LINE OF CODE which tells the kernel to send out an ack. Looks to me like a typo deleted a line by mistake. I posted this fact here quite a while ago, passed it on to some friends at dec, and would have filed an SPR but I don't have any Ultrix systems to file it under. I had hoped it would be fixed in V2.0 but I quess not. Maybe if I shame the Ultrix people in Nashville next week :-) -ed cetron