________________________________ From: Anne & Lynn Wheeler <l...@garlic.com> To: IBM-MAIN@bama.ua.edu Sent: Thu, March 11, 2010 8:43:50 AM Subject: Re: Entry point for a Mainframe? --------------------SNIP--------------------------------
The communication group then did a corporate study that claimed that there wouldn't be customer use of T1 until mid-90s (aka since they didn't have product that supported T1, the study supported customers not needing T1 for another decade). The problem was that 37x5 boxes didn't have T1 support ... and so what the communication group studied was "fat pipes" ... support for being able to operate multiple 56kbit links as single unit. For their T1 conclusions they plotted the number of "fat pipes" with 2, 3, 4, ..., etc 56kbit links. They found that number of "fat pipes" dropped off significantly at four or five 56kbit links and there were none above six. There is always the phrase about statistics lie ... well, what the communication group didn't appear to realize was that most telcos had tariff cross-over about five or six 56kbit links being about the same as a single T1 link. What they were seeing, was when customer requirement reached five 56kbit links ... the customers were moving to single T1 link supported by other vendors products (which was the reason for no "fat pipes" above six). The communication groups products were very oriented towards to the legacy dumb terminal paradigm ... and not the emerging peer-to-peer networking operation. In any case, a very quick, trivial survey by HSDT turned up 200 customers with T1 links (as counter to the communication group survey that customers wouldn't be using T1s until mid-90s ... because they couldn't find any "fat pipes" with more than six 56kbit links). this is analogous to communication group defining T1 as "very high speed" in the same period (in part because their products didn't support T1) ... mentioned in this post: http://www.garlic.com/~lynn/2010e.html#11 Crazed idea: SDSF for z/Linux the various internal politics all contributed to not letting us bid on the NSFNET backbone RFP ... even when the director of NSF wrote a letter to corporation ... and there were observations that what we already had running was at least five years ahead of RFP bid responses (to build something new). misc. old NSFNET related email from the period http://www.garlic.com/~lynn/lhwemail.html#nsfnet Ann In the mid 70's we had a T1 and we muxed it and IIRC we had 1 256K chunk and another chunk (sorry do not remember the speed) connected up to our 3745 and it worked really well (except a really strange bug which took us with the help of chance to figure out what the issue was). We were exercising it and kept it busy at least 20 out of 24 hours a day. I vaguely remember talking about the bug with IBM at the time (we were a small minority user of something like this at the time as IBM apparently only had a few people that seemed to know this part of NCP). Its not too surprising I guess that IBM really did not support a full T1 but if my memory (its iffy here) is correct it had something to do with the speed of the 3745 as to why IBM couldn't support it. SInce memory fades with time and I only remember small pieces we did seem to be on the bleeding edge at that time. Our bug turned out to not to have anything to do with NCP (per se) but I think if IBM would have had more experience they would have helped us find the issue sooner. IIRC there was semi documented information about lic weights (???) and you had to read it closely or you ended up with bad information. Sorry about the sketchiness but we are talking 35 years ago. Ed ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
