Path: utzoo!mnetor!uunet!mcvax!enea!ttds!rajaei From: rajaei@ttds.UUCP (Hassan Rajaei) Newsgroups: comp.protocols.tcp-ip Subject: Re: OSI does not mean X.25 Message-ID: <1157@ttds.UUCP> Date: 8 Apr 88 14:44:11 GMT References: <76.008873@adam.DG.COM> Reply-To: rajaei@ttds.UUCP (Hassan Rajaei) Organization: The Royal Inst. of Techn., Stockholm Lines: 36 In article <76.008873@adam.DG.COM> writes: > >Evidently there are still people who see "OSI" and hear "X.25" and >"connections". ** THIS IS NOT A VALID ASSUMPTION! ** > >You can have OSI with a Transport protocol similar to TCP (ISO 8073) >and a connectionless internetwork protocol (ISO 8473) even more similar >to IP. You do not have to have X.25. You do not have to have PTTs. >You do not have to have network connections. There is NO part of OSI I am really glad you mentioned this. There has been a confusion between OSI model and X.25 protocol for a long time just because X.25 was the only available implementation of OSI. The OSI model is so general that you may do any thing with it (except the overhead!). If there is not an standard protocol available for your need within the model, that doesn't mean the model itself is incapabel of doing that. In spite of many standard protocols available for OSI at present time, I believe we need many new ones in future even for the low layers like physical, link and network. The existing standars for low layers are incapable of handling the ultra super speed networks of the future (FDDI can handle just 150 Mbps). The same is true with X.25 and its IP X.75 which are not only limited by speed but rather make the network very vulnerable because of their connection- oriented behaviour throughout the network (internetworks). As Lyman Chapin said the limitation is not in the model but in the protocols. There is much to be done for OSI model to be accepted (or rejected!) world wide, both with new standard protocols and implementations. Hassan Rajaei The Royal Inst. of Technology Stockholm Sweden rajaei@tds.kth.se