dd@ariel.unm.edu (dd) (12/08/89)
I am trying to front-end an IBM 7171 with a CISCO ASM. I have gotten it to work, but there are some performance problems. Has anyone out there done this thing, and could I please ask you some questions? Thanks in advance. -- Don Doerner dd@ariel.unm.edu University of New Mexico CIRT 2701 Campus Blvd, NE Albuquerque, NM, 87131 (505) 277-8036
cire@CISCO.COM (cire|eric) (12/08/89)
This sounds interesting. What exactly is an IBM 7171 and how are you trying to connect the cisco to it? -c cire|eric "I could have done it in a much more complicated way", said the Red Queen, immensely proud. -- Lewis Carrol, Alice in Wonderland Eric B. Decker Token Ring Development cisco Systems - engineering Menlo Park, California email: cire@cisco.com uSnail: 1360 Willow Rd., Menlo Park, CA 94025 Phone : (415) 326-1941
dboyes@rice.edu (David Boyes) (12/12/89)
In article <8912090646.AA16735@ucbvax.Berkeley.EDU> cire@CISCO.COM (cire|eric) writes: > >This sounds interesting. What exactly is an IBM 7171 and how are you >trying to connect the cisco to it? >Eric B. Decker >cisco Systems - engineering >email: cire@cisco.com The 7171 is a protocol conversion box that provides IBM 3278 emulation for a large set of standard async ASCII terminals. It grew out of a research project at Yale that eventually produced a beastly gadget called a Series/1 that did essentially the same job, but was much more difficult to configure and use. The 7171 is essentially an industrial grade PC with a 370 channel interface and up to 64 async ports (minimum 8, expandable in 8 port increments) running a embedded program that translates keyboard input from popular ASCII terminals to the 3270-style data streams that IBM mainframes expect. It also translates 3270 data streams from the host into appropriate escape sequences for each type of supported ASCII terminal by doing lookup of sequences stored in EEPROM. Users can add new terminal types by running a configuration program on an ordinary IBM PC or PS/2 and download the configuration into the controller via a serial line. It's a very well-thought out box -- IBM did a good job with the Yale research. Some sites provide TCP access to their IBM boxes by attaching a terminal server to the async ports on a 7171 and configuring the terminal server to rotor between free ports, like this: | |--------| net | | |======== | |------|====| 7171 |======== large IBM iron |---| TS |====| | | |------|====| | | |--------| Users can then 'telnet' to the terminal server and be automagically assigned a 7171 port w/o having to drag serial cables all over the place (assuming their 'telnet' does a reasonable terminal emulator that the 7171 can understand -- although 7171s can deal with terminals as dumb as ADM-3s, so it doesn't have to be much). It's a pretty smooth setup, once you get all the configuration stuff right in the terminal servers *and* get the right cables and modem signals rigged between the terminal server and the 7171. My guess is that the original poster has probably set up something very much like this and is having some problems getting everything set up and working smoothly. Disclaimer: I don't work for IBM. I just like the 7171 -- I've babysat several of them in different places, and they're very well-behaved. 8-) -- David Boyes "... no love was left; All Earth was but one thought - and dboyes@rice.edu that was death Immediate and inglorious; and the pang of of famine fed upon all entrails - men Died and their bones were tombless as their flesh ..." - Lord Byron
robert@trwind.UUCP (Robert W. Snyder) (12/15/89)
Robert Snyder > >I am trying to front-end an IBM 7171 with a CISCO ASM. I have >gotten it to work, but there are some performance problems. Has >anyone out there done this thing, and could I please ask you some >questions? > I have not seen any responses on this that helped you with the 7171 problems so I thought I would try to help by sharing the problems I recalled. I developed a terminal server for TRW and I eventually had a field engineer interface one to a 7171 in a milking machine fashion. There were a few problems I had to contend with. 1. At the time the 7171 did not do xon/xoff flowcontrol properly Symptom: The network conection would appear to lock up or have character loss. Analysis: After looking at a lot of serial data analyzer output, I discovered that when the terminal server flow controlled the 7171, the 7171 not only discontinued the transmission of normal data traffic but also discontinued sending xons/xoffs, which caused it to enter a "catch 22" state where both sides where flow-controlled and neither could release flow-control until some action was taken by the other or it would drop characters on the floor because the 7171 refused to inform the terminal server that it could not receive anymore characters. Resolution: IBM fixed their code by offering an option to either allow flowcontrolling of flowcontrol characters or a mode that I needed to succeed that allowed flowcontrol characters to be transmitted. 2. The 7171 that I was interfacing to required that certain hardware lines be asserted to transmit characters to the unit. Once those lines were asserted the 7171 began transmiting characters almost instantly. Symptom: The user would see a message the looked like this "gin:" instead of "Login:" (I dont remember the actual message but it was some sort of logon message) Analysis: When the hardware line were asserted the network link was not quite up. It was a couple character times off Resolution: I fixed my code. I mention the second problem just because the 7171 was the only device I ran into that exhibited this operation. Disclaimer: My experiences with the 7171 are specific to interfacing problems I experienced about 3 to 4 years ago. I am not an expert on the 7171, just good with terminal servers and serial devices. -- Robert Snyder Disclaimer -- nobody claims dis, but me TRW Information Networks Division 23800 Hawthorne Blvd, Torrance CA 90505 USENET: trwind!robert INTERNET: robert@trwind.TRW.COM Phone 213-373-9161