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From: vjs@rhyolite.wpd.sgi.com (Vernon Schryver)
Newsgroups: comp.dcom.modems
Subject: Re: V32bis
Message-ID: <81164@sgi.sgi.com>
Date: 15 Jan 91 02:38:57 GMT
References: <19700002@inmet> <3713.27832d53@hayes.uucp> <89275@lll-winken.LLNL.GOV>
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In article <89275@lll-winken.LLNL.GOV>, casey@gauss.llnl.gov (Casey Leedom) writes:
> 
>   But you're right, as long as the applications you want to work with
> don't need it the full duplex channel, they'll be happy with a half
> duplex channel like that offered by HST or PEP.  However
> 
>    1.	Neither HST or PEP are international standards.  With the
> 	increasing move towards standards, especially in the typically
> 	provincial U.S., this is going to become a big problem
> 	disadvantage.

This is the arguement that said OSI would replace TCP/IP by 1985.  I know
because I took the OSI pledge in 1984.  I have since developed an opinion
about the accuracy any arguement based on such "circular lemming" logic.

"Blank will be popular real soon, because everyone will be using it."


>   2.	Half duplex modems are also going to fall on their face with the
> 	increasing incidence of home networks with SLIP/PPP links to work,
> 	X Terminals like the GraphOn and NCD/XRemote, and other
> 	applications which definitely need a full duplex channel.

On the contrary, X terminals would benefit from a good asymmetric splitting
of bandwidth.  Consider the nature of your typical xterm TCP traffic, in
terms of packet sizes and rates, including TCP acks.  I do not know what
the right split is nor how dynamic it should be.  It's "obvious" that an
automatic, instantaneous, infinitely variable split between 28.8/0 and
0/28.8 would be far better than 14.4 full duplex.  (Yes, it's also
obviously impossible to be either instantaneous or infinitely variable.)

The troubles we've seen with machines like the NCD over TB's are not
related to PEP, but to NCD's less than heavy weight implementation of
TCP/IP.  For example, no routing, even RIP, causes some hassle, although it
no doubt makes the code in the terminal smaller and easier to maintain.

That PEP and HST may be fading does not imply asymmetric modem protocols
are dead, any more that the fact that the 300/1200 async, private line
modem I used in 1970 is long forgotten, along with the fancy graphics
terminal and the computer it connected.


Vernon Schryver,   vjs@sgi.com