DECnet problems

[der Mouse]

I'm having a little problem with DECnet.  We have a VAX which is
running 4.3, and I undertook to write a DECnet for it.  (No, using
Ultrix is not an option, I'm afraid.)

This has been going smoothly until very recently.  The routers think
the node is reachable (no great feat).  Then I tried to make it
actively refuse connections instead of just sitting there.  So I made
it send Disconnect Initate messages in response to Connect Initate
requests.  This was all going very well.  I got everything to compile
and then went to test it.  Well, where do I test it from?

- Test from Ultrix 1.2 machine: works almost-fine.  The Ultrix machine
  gives me "Connection rejected by object".  (This is why it's "almost"
  fine: I was putting error 4, "Destination end user does not exist",
  into the DI message.)

- Test from Ultrix 2.0 machine: works just the same as the 1.2 machine.

- Test from VMS 4.4 machine: deathly silence.  NCP's `show node count'
  command on the VMS machine informs me that zero messages and zero
  bytes have been received from my test node!  Something is clearly
  wrong at a fairly basic level.

- Test from VMS 4.5 machine: same deathly silence.

Now it's not a mixup with the Ethernet cache, because the Ultrix 2.0
machine and the VMS 4.5 machine are both in another area on the far
side of some DECnet routers, while the Ultrix 1.2 machine and the VMS
4.4 machine are on the same Ethernet as the machine this work is
happening on.  Debugging information saved by my code indicates that it
thinks it's sending packets just the same in all cases (except, of
course, that it's sending them directly for the Ethernet hosts and to
the designated router router for the distant hosts).  Thus the problem
is not with my receiving the CI from VMS, for example.

Any ideas what could be going wrong here?  Interoperability with Ultrix
is all that's required for our application, but I can't help feeling
that there must be something basic wrong with what I'm doing if it will
talk to Ultrix but not VMS.  (I can provide great detail, including
complete dumps of the packets involved, if necessary.)

					der Mouse

			uucp: mouse at mcgill-vision.uucp
			arpa: mouse at larry.mcrcim.mcgill.edu