Path: utzoo!mnetor!uunet!husc6!bbn!uwmcsd1!ig!jade!ucbvax!VENUS.YCC.YALE.EDU!LEICHTER
From: LEICHTER@VENUS.YCC.YALE.EDU ("Jerry Leichter ", LEICHTER-JERRY@CS.YALE.EDU)
Newsgroups: comp.os.vms
Subject: re: DECServer and DECnet incompatibility??
Message-ID: <8712280028.AA22150@ucbvax.Berkeley.EDU>
Date: 27 Dec 87 21:23:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 27


	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