Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!rutgers!seismo!uunet!steinmetz!davidsen From: davidsen@steinmetz.UUCP Newsgroups: comp.dcom.modems Subject: Re: 9600 bps dialups Message-ID: <6142@steinmetz.steinmetz.UUCP> Date: Thu, 4-Jun-87 13:22:37 EDT Article-I.D.: steinmet.6142 Posted: Thu Jun 4 13:22:37 1987 Date-Received: Sat, 6-Jun-87 09:48:51 EDT References: <521@alliant.UUCP> Reply-To: davidsen@kbsvax.steinmetz.UUCP (William E. Davidsen Jr) Distribution: world Organization: General Electric CRD, Schenectady, NY Lines: 27 Keywords: fast modems V.32 In article <521@alliant.UUCP> steckel@alliant.UUCP (Geoff Steckel) writes: >Advertisements for V.32 -->REAL 9600 BAUD FULL DUPLEX<-- modems have >been appearing in the trade press. These cost (now) between >US$1500-2500 each (not cheap! (:-) ) but should be extremely useful to >high bandwith full duplex protocol users (e.g. UUCP mailers!). Say what? uucp (at least the sysV and BSD versions) don't seem to use bidirectional high speed. If you watch a modem running at a speed slow enough so you can see what's happening, the send channel is busy nearly 100% of the time, but the receive channel is used only for ACK packets. Because of this the USRobotics with 300 baud back channel works very nicely as far as I can see (I'm still waiting for mine). Am I missing something about uucp or are you? I'm told that using other window protocols that on long messages the line may actually turn around and send a buch of ACK packets back at 9600. This is invisible to the connected systems (except for a slight drop in throughput). The high speed to low speed bandwidth is 32:1, which should work as well as full duplex on any system which uses a reasonable packet size for send. Even window kermit, using 70 byte packets (or thereabouts) rarely turns the line around. The inherent delays at each end would leave a little slop. -- bill davidsen (wedu@ge-crd.arpa) {chinet | philabs | sesimo}!steinmetz!crdos1!davidsen "Stupidity, like virtue, is its own reward" -me