Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!caip!topaz!husc6!talcott!maynard!campbell
From: campbell@maynard.UUCP (Larry Campbell)
Newsgroups: net.sources.d
Subject: Re: \"FAST\" protocol proposal from Hayes
Message-ID: 
Date: Sat, 16-Aug-86 09:18:30 EDT
Article-I.D.: maynard.333
Posted: Sat Aug 16 09:18:30 1986
Date-Received: Sun, 17-Aug-86 10:11:00 EDT
References:   
Reply-To: campbell@maynard.UUCP (Larry Campbell)
Organization: The Boston Software Works Inc., Maynard, MA
Lines: 29
Keywords: errors reliability end-to-end CRC
Summary: reinventing an unreliable wheel

In article  davids@iscuva.UUCP (David Schmidt) writes:

>If you read the documentation carefully you will see that the FAST
>protocal does include the capability of using a CCITT CRC-16 check
>on the file sent.  If this is uses (I wouldn't use FAST without it!)
>then you do have an error-free protocal.

But the use of a CRC is optional.  I think they should make it
mandatory.  This is especially important in the PC world, with so many
people trustingly toting binaries around without sources.  In source
code, errors will almost certainly cause the code not to compile or
link, and will thus be detected.  In binary code, though, the errors
will just cause the code to explode in mysterious ways that are nearly
impossible to detect.

Note also that FAST just has one CRC for the entire file.  The longer
the packet, the greater the probability that CRC-16 will fail to
detect an error.  For almost any reasonably large file, CRC-16 is
nearly worthless.

In any event, why invent yet another protocol?  What's wrong with KERMIT
with sliding windows?  KERMIT is already implemented everywhere, and the
sliding windows give reasonable performance.  It just irks me no end to
see people simultaneously reinventing the wheel and giving up reliability
for performance.  It doesn't matter how fast you can do it wrong!
-- 
Larry Campbell                             The Boston Software Works, Inc.
ARPA: campbell%maynard.uucp@harvard.ARPA   120 Fulton Street, Boston MA 02109
UUCP: {alliant,wjh12}!maynard!campbell     (617) 367-6846