Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!cbmvax!grr
From: grr@cbmvax.UUCP (George Robbins)
Newsgroups: comp.dcom.modems
Subject: Re: Best modems for SLIP: summary of responses
Message-ID: <6992@cbmvax.UUCP>
Date: 26 May 89 11:49:42 GMT
References: <17691@mimsy.UUCP> <1989May23.173557.1790@utzoo.uucp> <1989May25.015027.7319@tmsoft.uucp>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Organization: Commodore Technology, West Chester, PA
Lines: 32

In article <1989May25.015027.7319@tmsoft.uucp> mshiels@tmsoft.UUCP (Michael A. Shiels) writes:
> 
> If small backchannels hurts SLIP then wouldn't full duplex V32 modems work
> a lot better?

Obviously!  Full duplex V.32 would be ideal for SLIP at 9600 baud.  However,
given a modem that understands SLIP packets and optimizes for this, you
could have 9600->19200 buad in direction of the main data flow and whatever
is needed to the less demanding direction.  A 1.5x or better improvement in
communications speed is probably worthwhile, especially in interactive
situations.

On the other hand, a non-V.32 modem that doesn't understand slip and plays
adaptive half-duplex/back channel games, may give lousey performance since
it doesn't understand packet boundries or acknowledgment.  In this case
the USR HST asymetrical back channel might work better than a Telebit and
might give performance similar to a V.32 modem on a lightly loaded link.

On a fully loaded link with similar volumes of data going in both directions,
you'd need something that actually delivers an aggregate throughput of greater
than baud to beat the V.32 modem (assuming the V.32 modem is getting 19.2K). 

At present, I don't have any slip connections, and lots of UUCP and dial-in
connections, so the question is somewhat academic.  I did order a pair of
the T2500 modems to *play* with, along with a pile of T1000's and TB+'s to
*work* with.  8-)

Time will tell.
-- 
George Robbins - now working for,	uucp: {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing	arpa: cbmvax!grr@uunet.uu.net
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)