Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!wuarchive!usc!snorkelwacker!bu.edu!shelby!msi-s0.msi.umn.edu!cs.umn.edu!cybrspc!roy From: cybrspc!roy@cs.umn.edu (Roy M. Silvernail) Newsgroups: alt.sources.d Subject: Re: v11i020: Idle demon Message-ID: Date: 25 Aug 90 03:11:56 GMT References: <1138@mpirbn.mpifr-bonn.mpg.de> Organization: Villa CyberSpace, Minneapolis, MN Lines: 28 p554mve@mpirbn.mpifr-bonn.mpg.de (Michael van Elst) writes: > In article <2868@wyse.wyse.com> bob@wyse.UUCP (Bob McGowen x4312 dept208) wri > >If my understanding of "sliding window" protocols is correct, it IS possible > >for a download to never (or seldom) have a response. The basic idea is that > >if an error has not occured, why spend the overhead to ack the packet. > > No, even with a "sliding window" protocol, acknoledgements are sent. > The main difference is that you don't wait for an ack to continue > transmission but wait if a specified number (window size) of acks > is missing. I think Bob is thinking of a streaming protocol, such as Zmodem. Zmodem will leave the return channel completely empty, unless an error is discovered by the receiving end. Streaming protocols are, of course, distinct from sliding-window protocols. Now, the question in my mind (and this really has nothing to do with the original thread :-) is... which type is SEAlink? I have used it on several systems, and had varying results. In some cases, it has behaved as a streamer (with no activity seen on the alternate-channel modem light), and sometimes it's acted like a sliding-window, if not downright packetized. -- Roy M. Silvernail | #include | Does virtual now available at: | main(){ | reality need cybrspc!roy@cs.umn.edu | float x=1; | swap space? (cyberspace... be here!)| printf("Just my $%.2f.\n",x/50);} | -- me