Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ucbvax!hwalhw50.BITNET!DEGROOT From: DEGROOT@hwalhw50.BITNET ("Kees de Groot ", DEGROOT@HWALHW50) Newsgroups: comp.protocols.misc Subject: RE: Personal protocols: Where do they fit in the big picture? Message-ID: <8810241351.AA29661@rutgers.edu> Date: 24 Oct 88 08:52:00 GMT Article-I.D.: rutgers.8810241351.AA29661 Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 32 Hamed Nassar wonders: > === personal protocols: where do they fit in the big picture === > People have been asking me this question. Personal protocols (such as > kermit, xmodem, ymodem, modem, tlink, sealink, link, >cis a, cis b, cis , etc..etc.(where banana = any thing)), where >do they fit in the ISO reference model? I would say they represent the application layer. There are two applications at both sides communicating with each other, more or less duplicating functions of the lower layers. If the lower layers provide more functionality you can choose a more appropriate protocol. Eg. if you use one of those ISDN-killing-modems which transport data error-free at astonishing speeds then you can use a simpler protocol. But if you have no error-handling what so ever then you should use a protocol that handles this itself. Modems as the Telebit trailblazer do 'protocol-spoofing'. They collect packets ACKing each packet directly to the host and send them in one long datapacket to the other modem which handles them one by one to the receiving host. I have always thought you could see this as a (confusing) implementation of the layers 1,2 and 7 (physical, data- and application layer). Comments? Tel. +31-8370- .KeesdeGroot (DEGROOT@HWALHW50.BITNET) o\/o THERE AINT NO (8)3557/ Wageningen Agricultural University [] SUCH THING AS 4030 Computer-centre, the Netherlands .==. A FREE LUNCH! X25: PSI%(+204)18370060638::DEGROOT DISCLAIMER: My opinions are my own alone and do not represent any official position of my employer. - if you go too far to the east, you find yourself in the west .. -