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From: paul@csnz.co.nz (Paul Gillingwater)
Newsgroups: comp.dcom.modems,comp.mail.uucp
Subject: Re: Telebits and uucp g-protocol
Keywords: Telebit Trailblazers, g-protocol, uucp
Message-ID: <47@csnz.co.nz>
Date: 14 Jun 89 19:33:44 GMT
References: <335@nixtor.UUCP>
Reply-To: paul@csnz.co.nz (Paul Gillingwater)
Organization: Computer Sciences of NZ Limited
Lines: 35

In article <335@nixtor.UUCP> davidm@nixtor.UUCP (David Macklem) writes:
>I  have a number of questions about Telebits and the g-protocol
>spoofing that they do. Hopefully someone out there will explain.
Oh, I couldn't resist answering this one.  Sorry my reply is
a bit late: comes of living 10,000 miles away I guess...

>I understand that the Telebit TB+ modems can do the uucp g-protocol
>between themselves. This ability sure is nice but it doesn't really
>offload the CPU that much, does it? 
The key word here is "spoof".  Two matched TB's running at 19,200
on their DTE interfaces will "pretend" to do uucp - but in reality
they are using their own protocol, called PEP, which is a packetised
error-correcting ARQ type protocol.  The TB's will feed all the
right answers back to uucico so that it thinks it's talking uucp-g
with another uucico -- but it's not.

>My second question is related to the first. Since the Telebits can do
>the error-checking and correction themselves why don't all uucico's
>communicating using modems that agree on some protocol use the
>f-protocol? 
The danger of assuming that you are using an error-free link is that
the end-points are not secure.  By that, I mean that you can lose 
characters at each end due to things like missed interrupts,
overrun errors between the modem and the computer due to poor 
handshaking, etc. That's why it's better to allow the protocol
to check.
>Any takers?
Yep!
>David Macklem 		Nixdorf Computer Canada, Limited
From a fellow colonialist...

-- 
Paul Gillingwater, Computer Sciences of New Zealand Limited
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