Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!uunet!telebit!brian From: brian@telebit.com (Brian Lloyd) Newsgroups: comp.dcom.modems Subject: Re: MNP 10 (was: T1000) Keywords: V.32 MNP 10 QX/4232hs Message-ID: <1991May9.052239.20672@telebit.com> Date: 9 May 91 05:22:39 GMT References: <1991May01.021126.1382@nstar.rn.com> <1991May8.233217.3108@am.dsir.govt.nz> Sender: news@telebit.com Organization: Telebit Corporation; Sunnyvale, CA, USA Lines: 39 Nntp-Posting-Host: napa.telebit.com bkc@am.dsir.govt.nz (Barney Campbell) writes: >tim@dal.fsd.mot.com (Tim Dawson) writes: >> ... The problem is simply this: V.32 knows 9600 and 4800 baud - - - - >> PERIOD! If you train down to 4800 and then retrain again and 4800 for >> some reason is not clean (line hit, etc) V.32 standard says to >> DISCONNECT - they are incapable of continuing from this point, and >> also cannot train back up to 9600 once fallback has occured. This is >> not a problem with a vendor, this is a problem with a protocol - V.32 >> does not have the same kine of robust error recovery and correction as >> PEP. ... >Presumably this is the kind of problem Microcom is seeking to give a >solution for by providing MNP class 10 (Adverse Channel Enhancements [TM]) >(including speed recovery) in for example the QX/4232hs V.32 modem. >Barney Campbell MNP 10 does not address the issue of the quality of the underlying data pump. This leads to a process whereby someone attempts to "cure" the problem with a link by adding an error correction scheme. This will serve to buy you a few db but it won't solve the problem when the data pump has insufficient S/N to retain synchronization. I like V.32 and V.32bis (especially when I am running SLIP or PPP). They work great over most landlines in the United States. PEP is still a win when the link is marginal as in a cellular phone or an international call. Sometimes the right tool is a rifle and sometimes the right tool is a shotgun. Brian -- Brian Lloyd, WB6RQN Telebit Corporation Network Systems Architect 1315 Chesapeake Terrace brian@napa.telebit.com Sunnyvale, CA 94089-1100 voice (408) 745-3103 FAX (408) 734-3333