MANAGER@SKIDMORE.BITNET (Leo Geoffrion) (12/21/87)
Some internal DEC documentation for the DECserver 500 suggest that it may be incompatible with asynchronous DECnet. In other words, if you intend to use asynchronous DECnet to connect to micros with either DECnet DOS or TSSnet (for the Mac's), then you cannot use a Terminal Server for your communication port. This is somewhat annoying since DEC is steering most buyers toward the DECservers as the preferred mode for user i/o. At the same time, we find that asynchronous DECnet provides the nucleus for integrating micros and Vaxen without expensive Ethernet boards on every micro. (our 9600 Baud PBX lines are fast enough for most small files). Is it indeed impossible to connect asynchronous DECnet on top of LAT-11? Has anyone seen a work-around for this? I'd really hate to have to go back to reinstalling our old DZ-11's. =================================================================== Leo D. Geoffrion BITNET: MANAGER@SKIDMORE.BITNET Associate Director for NYNEX: (518) 584-5000 Ext. 2628 Academic Computing Skidmore College Saratoga Springs, NY 12866
WARNER..NAGY@FNALB.BITNET (Frank.J.Nagy@jade.Berkeley.EDU, (12/23/87)
Leo Geoffrion <MANAGER%SKIDMORE.BITNET@CUNYVM.CUNY.EDU> writes: > Some internal DEC documentation for the DECserver 500 suggest that it may > be incompatible with asynchronous DECnet. In other words, if you intend > to use asynchronous DECnet to connect to micros with either DECnet DOS or > TSSnet (for the Mac's), then you cannot use a Terminal Server for your > communication port. > Is it indeed impossible to connect asynchronous DECnet on top of LAT-11? > Has anyone seen a work-around for this? I'd really hate to have to go back > to reinstalling our old DZ-11's. This might well be true. However, you might want to look into another Digital product, the DECRouter-200 (I think its -200 and not -100), this is a box based upon the DECServer-200 (8 lines) which becomes a DECnet router box on the Ethernet and provides up to 8 asynchronous DECnet connections for PCs, etc. In other words, this does exactly what you want it too and, since the DECRouter is self-contained, does not impose additional load on your host VAXes to handle the async DECnet connections. = Frank J. Nagy "VAX Guru & Wizard" = Fermilab Research Division EED/Controls = HEPNET: WARNER::NAGY (43198::NAGY) or FNAL::NAGY (43009::NAGY) = BitNet: NAGY@FNAL = USnail: Fermilab POB 500 MS/220 Batavia, IL 60510
tedcrane@batcomputer.tn.cornell.edu (Ted Crane) (12/24/87)
In article <8712222310.AA00987@ucbvax.Berkeley.EDU> MANAGER@SKIDMORE.BITNET (Leo Geoffrion) writes: >Some internal DEC documentation for the DECserver 500 suggest that it may >Is it indeed impossible to connect asynchronous DECnet on top of LAT-11? >Has anyone seen a work-around for this? I'd really hate to have to go back >to reinstalling our old DZ-11's. Bullseye. As of the last time I tried this (DECnet via LAT), it didn't quite work. DEC documents it as not working. Typically, DECnet will come up briefly, then fail when you start using it in a non-trivial manner. Sometimes i fails without even being used. I had quite a series of conversations with DEC folk about this limitation, commenting on the dilemma between DEC's current steering of customers toward LAT terminals, but not supporting async DECnet on them. It is a big dilemma when you take into account the proliferation of cheap, standalone VAXen which can reasonably connect to the office network only by telephone line. Unless someone submits an article to contradict your and my experience, why don't we all continue pushing Dr. DEC on this issue. It needs changing!
LEICHTER@VENUS.YCC.YALE.EDU ("Jerry Leichter ", LEICHTER-JERRY@CS.YALE.EDU) (12/28/87)
Some internal DEC documentation for the DECserver 500 suggest that it may be incompatible with asynchronous DECnet. In other words, if you intend to use asynchronous DECnet to connect to micros with either DECnet DOS or TSSnet (for the Mac's), then you cannot use a Terminal Server for your communication port. This is somewhat annoying since DEC is steering most buyers toward the DECservers as the preferred mode for user i/o. At the same time, we find that asynchronous DECnet provides the nucleus for integrating micros and Vaxen without expensive Ethernet boards on every micro. (our 9600 Baud PBX lines are fast enough for most small files). Is it indeed impossible to connect asynchronous DECnet on top of LAT-11? Has anyone seen a work-around for this? I'd really hate to have to go back to reinstalling our old DZ-11's. Running async DECnet over LAT sometimes works, and sometimes doesn't. The fundamental problem is that both levels are doing timeouts and retries, and they can interfere destructively. The result: Sometimes it works, sometimes it doesn't. If you have a clean, relatively unloaded Ether, the links between your micros and your DECServer are also clean, your hosts aren't very heavily loaded, and your DECServer isn't very heavily loaded - basically, if the setup makes clobbered packets, hence retries, extremely unlikely - you may get re- sults you are happy with, or at least can live with. It's tough to say for sure, which is exactly why it's not supported. -- Jerry
tpmsph@ecsvax.UUCP (Thomas P. Morris) (12/29/87)
In article <8712250035.AA24175@jade.berkeley.edu>, WARNER..NAGY@FNALB.BITNET (Frank.J.Nagy@jade.Berkeley.EDU, writes: > you might want to look into another > Digital product, the DECRouter-200 (I think its -200 and not -100), this > is a box based upon the DECServer-200 (8 lines) which becomes a DECnet > router box on the Ethernet and provides up to 8 asynchronous DECnet > connections for PCs, etc. In other words, this does exactly what you ^^^^^^^^^^ > want it too and, since the DECRouter is self-contained, does not impose ^^^^^^^^^^^ > additional load on your host VAXes to handle the async DECnet connections. > It's not entirely clear that the DECrouter-200 does exactly what many sites want to do: mix, on a dynamic basis, regular asynchronous terminal connections with dynamic asynchronous DECnet (DDCMP protocol) connections, often from the same terminal line connected to a PC. DECnet-DOS is great for _some_ uses, such as wildcarded massive file transfers (where it easily outperforms, in both transfer speed and VAX CPU efficiency, systems like Kermit, and XMODEM or HST/XFR), and even for multiple terminal sessions via SETHOST. But the "responsiveness" of the SETHOST/CTERM terminal emulation in DECnet-DOS leaves __much__ to be desired. (No flames, please: I fully under- stand _why_ the lack of responsiveness occurs.) For that reason, among others, it is very desirable to be able to alternate normal asynchronous connections and dynamic asynchronous DECnet (DDCMP protocol) connections from a single line attached to a PC. (Accomplished via PC/MS-DOS BAT files which rename the autoexec and config files, after which a quick ctrl-alt-del reboot brings up the PC in the desired configuration.) It is not clear, though, from the scant information I've seen in the Networks and Communications catalogs, whether a DECrouter-200 _can_ mix regular asynch and DDCMP connections! Anyone out there with one of these beasts who knows? Tom Morris UNC School of Public Health Division of Computing and Information Systems tom@uncsphvx.bitnet or tmorris@uncsphvx.bitnet or ...!mcnc!ecsvax!tpmsph
tpmsph@ecsvax.UUCP (Thomas P. Morris) (12/29/87)
It appears that the reason why DECservers do not support asynchronous DECnet connections, is that the LT-class terminal port driver used by LAT prototocl connections does not support the SET TERM/PROTO=DDCMP/SWITCH command. FOr the other terminal drivers used by hardwired terminal port inter- faces, this command has the effect of "hooking" the DDCMP protocol driver software into the communications chain "between" the hardware interface and the VMS terminal driver communications handler. (This is a gross over- simplification, but it catches the flavor of what occurs---the terminal line is put into a passall-like mode, and the DDCMP driver handles packet assembly and disassembly, and sequencing and verification according to the DDCMP protocol.) As Mr Nagy alluded to in a previous posting, dynamic asynchronous DECnet (DDCMP protocol) connections _do_ "cost" in terms of overhead on the DECnet host handling the connection. It costs in terms of CPU and interrupt overhead. DECserver async (LAT protocol) connections are more efficient than either DDCMP or normal TX or TT --style async (RS232/ASCII) connections. But the question still exists: WHY IS DDCMP NOT SUPPORTED ON DECSERVERS??!! By setting terminals into passall or similarly transparent modes, other protocols such as Kermit or XMODEM or HST/XFR can be run on DECserver LT-class terminal ports! Supporting DDCMP ought to be possible: 1.) set the terminal-to-DECserver connection to passall or other transparent mode, as used by Kermit, XMODEM, HST/XFR et al; 2.) let the DECserver-to-LAThost connection continue to run normal LAT protocol. (Use LAT as a transport service: this is just what Kermit et al do.) 3.) at the LAThost end of the connection, "connect" a DDCMP protocol driver (protocol _only_: hardware driver not needed as LAT provides the hardware equivalent of the packet transport service trans- parently) BETWEEN the LAT character transport service and the QIO interface. Perhaps this has not been done because the LAT character transport service is __too tightly integrated__ with the QIO interface? Yes, I _do_ recognize that this method would "cost" almost as much LAThost overhead as the standard asynchronous DDCMP terminal driver configuration. On the other hand, this would provide equivalent capability to normal async software, without requiring additional hardware! After all, we didn't have to buy special "hardware" to run DDCMP on our existing terminal cards; why should we have to buy DECrouters? Tom Morris UNC School of Public Health Division of Computing and Information Systems tom@uncsphvx.bitnet or tmorris@uncsphvx.bitnet or ...!mcnc!ecsvax!tpmsph