ebd@fang.ATT.COM (Elliot B Dierksen) (03/06/91)
I just recently got a Telebit T2500 and I have some questions about what
certain things are. I know that PEP is it's own protocol and that compression
is a modification of the data. I know that MNP goes on top of Bell and
V.2[12] modes. I know V.32 is it's own thing and I think MNP can be used in
conjunction with it. I guess my question is really: What are V.42 and LAP-M?
Are they used in conjunction with V.32 or do they replace it?? My first
choice response would be a book I can buy that explains all this type of
stuff. I understand how PEP handles the multi-carrier transmission, but I
would like a technical explanation of V.[34]2 and LAP-M.
Any help would be greatly appreciated,
EBD
--
Elliot Dierksen "It's such a fine line between clever and stupid."
-- "This is Spinal Tap"
Work) ebd@fang.att.com (407) 660-3377
Home) elliot@alfred.UUCP (407) 290-9744tnixon@hayes.uucp (03/07/91)
In article <1991Mar5.192716.28859@fang.ATT.COM>, ebd@fang.ATT.COM (Elliot B Dierksen) writes: > I just recently got a Telebit T2500 and I have some questions about what > certain things are. I know that PEP is it's own protocol and that compression > is a modification of the data. I know that MNP goes on top of Bell and > V.2[12] modes. I know V.32 is it's own thing and I think MNP can be used in > conjunction with it. I guess my question is really: What are V.42 and LAP-M? > Are they used in conjunction with V.32 or do they replace it?? My first > choice response would be a book I can buy that explains all this type of > stuff. I understand how PEP handles the multi-carrier transmission, but I > would like a technical explanation of V.[34]2 and LAP-M. Well, one thing you could do is look at the "lexicon" that is periodically published in this newsgroup. I think it adequetely answers your questions. But I'll address the V.42 issue here, anyway. CCITT Recommendation V.42 is the international standard for error control in modems. It can be used in conjunction with any full-duplex modulation scheme that uses async-to-sync conversion (e.g., Bell 212, V.22, V.22bis, V.26ter, V.32, V.32bis). It specifies two protocols: a primary protocol in the main body of the standard, known as LAPM (link access procedure for modems), and an alternative protocol, specified in an annex, which provides for backward compatibility with modems that implement MNP classes 2-4. LAPM is based on prior existing international standards HDLC (high-level data link control), LAPB (X.25), and LAPD (ISDN). The alternative protocol is "frozen" and will not be extended; all future enhancements to V.42 will apply only to LAPM. This includes, for example, Recommendation V.42bis, which is the international standard for data compression in modems. -- Toby Nixon, Principal Engineer | Voice +1-404-840-9200 Telex 151243420 Hayes Microcomputer Products Inc. | Fax +1-404-447-0178 CIS 70271,404 P.O. Box 105203 | UUCP uunet!hayes!tnixon AT&T !tnixon Atlanta, Georgia 30348 USA | Internet hayes!tnixon@uunet.uu.net