>you sure? > >well, OK, I actually braved my garage and dug out my old text Business >Telecommunications by Sanford Rowe. This is the one that hooked me into >networking as opposed to PC support 15 years ago. I vaguely recalled SNA as >being nine layers, but I must have confused that with the nine bits in an >EBCDIC character. > >In any case, there it is - OSI and SNA side by side. Wow it's been a while. >Interesting the way the two organizations pictured how data communications >works. > >Wonder if Howard has any comment as to the relative merits of either >perception?
In my days at the Corporation for Open Systems, I remember both John Aschenbrenner, the lead SNA architect at the time for IBM, and Rick McGee, director of the SNA architecture center, say it was pure coincidence. John also noted that no one in IBM ever came up with a coherent explanation of why there is no Physical Unit Type 3, although the best guess is that at one point it dealt with media. While the number of layers in the original (NOT evolved) models happened to be the same, the architectural principles, especially in management, were quite different. SNA was hierarchical while OSI was peer-to-peer. APPN/APPC was the evolution to an architecture much more like OSI and the Internet suite, but still had to retain legacy compatibility. > >Another aside, and it has been a very long while since I read this, so I >can't validate either its accuracy or my memory, but at one time the largest >seller of "OSI compliant" gear in the world was IBM. Probably due to their >selling into the US Govt GOSIP market. I can't say IBM was the largest, but I do remember that IBM had an extensive OSI product line that they refused to sell in the US until GOSIP was passed. They released it in the US a few days later. They were so serious about this policy that they were judged non-responsive when they refused to quote OSI software to to the very visible Corporation for Open Systems, the North American OSI/ISDN consortium. > >Tanks for the memories. > >Chuck > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] >Sent: Monday, December 10, 2001 8:56 AM >To: [EMAIL PROTECTED] >Subject: Re: Does session layer protocol use IP address ? [7:28378] > > >I was told that there are 7 layers in the OSI model (from a guy who worked >on this stuff back in the early 80's) only because IBM's protocol had 7 >layers at the time, and OSI had 6. They added the session-layer to make it >seem like a viable model. True story. :) > >Steve Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=28785&t=28378 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
