[HECnet] MVS and DecNet

[hvlems at zonnet.nl]

DEC had two hardware solutions. The channel attached gateway and a gateway that used a serial interface. The -CT was the size of a VAX 4500, the -ST the size of a LANbridge 100 (to give you an idea). 
The advantage of the -CT over the -ST was the simultaneous sessions it supported, 1024 vs 256.   Important if one used RJE stations because each RJE station used at least one cardreader, console and printer session. I thinks the cardpunch was optional but if you needed more output streams it was useful. 
The -CT connected to ethernet and connected to just one IBM host via its channel interface. All systems that supported the SNA/DECnet package could set up sessions to the -CT and thus the IBM. 
The -ST was kind of point to point: serial to the IBM and synchronous to the VAX host.   (IIRC ..)
The IBM used SNA on either DOS/VSE or MVS.   The latter also supported access to its filesystem, so $ DIR IBM::*.* was possible. An additional SNA gateway software product was required. 
The 3174 emulation was for terminals, it was implemented with yet another box. I forgot which one. It connected to a control unit and the serial backend was hard wired to two DECservers 200 that offered the (reverse) LAT service IBM to the ethernet. Worked a lot better than 3174 emulation on token ring connected Novell pc's. (All this happened between 1988 and 1994). 
In those days DECnet was the lingua franca on the LAN. Phase 4. No way phase 5 could talk directly to VTAM. The hardware gateway products only implemented phase 4. 
There was an SNA product that ran natively on a VMS system, it used a DMF32 to connect to the IBM (at least my memory thinks it was a DMF32. May just as well have been something else :-) . Same functionality as the -ST without the DEMSA box. 
Hans
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Van: Sterling Garwood
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Aan: Sampsa Laine
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Onderwerp: [HECnet] MVS and DecNet
Verzonden: 4 augustus 2012 16:35

Saw your note on Hecnet about MVS and DecNet

I've run MVS 3.8J on Hercules for years on Macs and PCs (usually on Linux)
ISTR that DEC had an interface that sat on the IBM channel and looked like a 3274 control unit --- I also remember going to a demo at DEC late in their life and watching the product crash over and over :-)

The place I worked ended up installing TCPIP on the 370s to talk to the Vaxen - I believe it was a port of the Stanford or UCLA code (don't remember which).
Anyone who needed terminal access to the mainframe went thru the Vax that was the gateway.

Sterling Garwood
slgarwood at charter.net