mskuhn@faui09.informatik.uni-erlangen.de (Markus Kuhn) (02/02/91)
Some days ago, I asked here about possibitilies for OSI connections on asynchronous/start-stop RS-232 lines. There seems to be some interest in this topic. I got some suggestions: 1. H.T.Alvestrand suggested me to check X.32 in the CCITT Blue Book. I did this. Unfortunately this recommendation says only something about synchronous modes on the V.24 (= RS-232) interface. The other modes are "for further study" (section 4.3.1). Perhaps they intend to use the new HDLC start-stop mode as a further option in the '92 version. 2. Tim Clark reported that in the UK acedemic community, a protocol called ATS is used to convert LAP-B in an asynch protocol. 3. Micheal Roe reported that there is a standard in the TCP/IP world called 'Serial Line IP' that does exactly what I want. So I could run X.25 over TCP/IP. He also suggested to modify LLC-1 (also a HDLC subset) for asynchronous lines in the same way, HDLC does this. This would be the connectionless alternative to my own suggestion of an asynch LAP-B. As I personally prefer X.25, I think, I will implement LAP-B. But the idea of using LLC-1 sounds also quite interesting to me. Unfortunately, ATS and Serial Line IP aren't pure OSI so I don't like them so much. Thank you for your answers. Any further suggestions? Has anyone information about the HDLC start-stop mode (frame format, transparency, etc.)? Is anyone planning to implement something like this? Especially in ISODE (would be great)? Markus Kuhn CS student