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From: casey@gauss.llnl.gov (Casey Leedom)
Newsgroups: comp.dcom.modems
Subject: Re: V32bis
Message-ID: <89275@lll-winken.LLNL.GOV>
Date: 12 Jan 91 03:27:12 GMT
References: <19700002@inmet> <3713.27832d53@hayes.uucp> <87110@tut.cis.ohio-state.edu> <3722.278c7fbc@hayes.uucp> <6130@khaki8.UUCP>
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| From: necka@motcid.UUCP (William J. Necka)
| 
| | From:  tnixon@hayes.uucp (Toby Nixon)
| | 
| | | From: bsmith@rose.cis.ohio-state.edu (brentley r smith)
| | | 
| | | How does V.32bis compare to "HST", U.S. Robotics' proprietary protocol?
| | | Are the mechanics of the protocols similar?  Is the (theoretical)
| | | throughput similar?
| | 
| | If you only transmit in one direction, the theoretical throughput of
| | V.32bis and HST are identical. ...  Of course, the performance of V.32bis
| | is vastly superior to HST when transmitting in both directions
| | simultaneously, which is required in many high-speed applications.
| | Full-duplex modems are much more flexible in terms of the applications
| | which can be supported.
| 
| 	On the contrary, the success of the HST demonstrates that the
| majority of applications make little demand in one direction, while
| maximizing the other.

  Toby didn't say that the majority of applications need to transmit in
both directions simultaneously.  He said that a full duplex connection
offered you more flexibility ``in terms of the applications which can be
supported [effectively.]''

  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.

    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.

| 	Because the HST does not have too cancel it's own echo, it can
| train/retain is milliseconds instead of seconds.

  The long retrain problem has been essentially solved with V.32bis.

| 	Granted the V.32 performance can be better in full-duplex
| operation; however that was not its intended design [of HST].  Providing
| fast file transfers at a reasonable price was.

  Last I looked the HST (and PEP) modems were fairly expensive compared
to the new V.32 modems appearing from just about every modem
manufacturer.  I expect that V.32bis will be adopted very quickly by the
same manufacturers and competition will push the price down well below
the HST (and PEP) proprietary modems.

  Now, I don't really want to paint too rosy a picture because I'm
suffering from V.32 connections dropping all the time in my new home.  My
PEP connections never drop (I have no idea how well HST does with
marginal lines.)  Thus, PEP is by no means a ``total failure.'' I just
wish we had something that was as robust as PEP and had descent full
duplex performance.

Casey