Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!pacbell!att!chinet!les
From: les@chinet.UUCP (Leslie Mikesell)
Newsgroups: comp.dcom.modems
Subject: Re: 'g' & packet sizes & extensions
Message-ID: <6517@chinet.UUCP>
Date: 6 Sep 88 17:19:54 GMT
References: <7272@bigtex.uucp> <10500003@osiris.cso.uiuc.edu> <6452@chinet.UUCP> <7832@mtune.ATT.COM> <169@arnold.UUCP>
Reply-To: les@chinet.UUCP (Leslie Mikesell)
Organization: Chinet - Public Access Unix
Lines: 20

In article <169@arnold.UUCP> dave@arnold.UUCP (Dave Arnold) writes:

>I really doubt the 'd' protocol has goals much different than 'x' or
>'e' or 't'.  Seems like all these could have been combined into one.
>One prococol for an error-free channel.  Or am I missing somehting?

E protocol does no flow control or error checking of its own which makes
it reasonable only over network connections where end-to-end error checking is
already done.  Even with trailblazers there is the link between the serial
port and the modem, and the problem of flow control.  The need for different
protocols follows the transmission channel requirements (i.e. is it 8-bit
transparent, does it have a turn-around delay, is flow control required..).
Then the protocol needs to be tuned for frame size and the window of 
unacked data (keeping in mind the question of "How much data are you
willing to throw a something that may be trying to interpret it as
dialing commands or operating system commands or...").  Since the
uucico convention is to select a protocol by a letter code with no
parameters, the different protocols are required.

Les Mikesell