Path: utzoo!utgpu!watserv1!watmath!att!linac!uwm.edu!rpi!clarkson!grape.ecs.clarkson.edu!nelson From: nelson@sun.soe.clarkson.edu (Russ Nelson) Newsgroups: comp.protocols.tcp-ip.ibmpc Subject: Re: FTP PC/TCP and Clarkson's NCSA Telnet living together Message-ID: Date: 24 Feb 91 05:51:37 GMT References: <210@hermix.UUCP> Sender: @grape.ecs.clarkson.edu Reply-To: nelson@clutx.clarkson.edu (aka NELSON@CLUTX.BITNET) Organization: Clarkson University, Potsdam NY Lines: 27 In-Reply-To: lance@hermix.UUCP's message of 21 Feb 91 21:57:41 GMT In article <210@hermix.UUCP> lance@hermix.UUCP (Lance Ellinghouse) writes: I would like to be able to use FTP's PC/TCP and IDRIVE (TCP/IP and NFS) while using Clarkson's version of NCSA Telnet. No can do, for two reasons, the first trivial: 1) The packet driver specification only requires a driver to deliver packets to a single receiver. That means that only one protocol stack will ever see the IP packets. There is software for Clarkson-derived packet drivers that will deliver a single packet to multiple receivers. That gets us to problem 2, the serious one: 2) If you had multiple TCP stacks, which one would should the acks be delivered to? Both of them? Only the "right" one? What happens if both stacks tried to glom onto the same UDP port? Who answers ARP requests? Yes, you can get this to "work" by ensuring that one of your IP stacks uses only UDP. Then your problems are merely terrible, as opposed to insurmountable. [I exaggerate the problems -- but it's still not a good thing to do.] -- --russ I'm proud to be a humble Quaker. It's better to get mugged than to live a life of fear -- Freeman Dyson I joined the League for Programming Freedom, and I hope you'll join too. Brought to you by Super Global Mega Corp .com