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Ask the Wizard Questions

DECnet setup

The Question is:

I'm not very familiar with openvms yet but i'll be going
for the training soon.  Anyway I have just installed a
brand new vax4000 (NEWVAX) and I've been trying to configure
the network.  I have another vax4000, let's call it OLDVAX.
My problem is I cannot set host to OLDVAX from NEWVAX
unless I do a set host to NEWVAX from OLDVAX first.
"Set host NEWVAX" works all the time.
"Set host OLDVAX" only works if I do it right after I do
"set host NEWVAX" from oldvax.
Could you please advise why this is so.

Appreciate it, thanx.

The Answer is:

SET HOST is a DECnet application - what version of DECnet is being used?  I
would guess Phase IV.

I wonder what the failing SET HOST command returns as the error message.

SET HOST simply tries to establish a logical link to the CTERM object on the
specified target node.  The image on the local side is RTPAD.EXE.

One thing that can go wrong is if the remote node database is not correctly
setup.  What does NCP SHOW NODE OLDVAX say?  It seems to me that it must be
right or it would never work.

The link request doesn't go directly to the target, rather, it first is sent to
the router - unless there is no router.  NCP SHOW KNOWN CIRCUIT to see the
adjacent router.  The router forwards the link request packet to the target and
doesn't clear the on-Ethernet bit if appropriate.  The target caches the
Ethernet address of NEWVAX and uses it to transmit directly, skipping the router.

Perhaps we have a node number conflict?  SHOW NET on both nodes.

So the following scenario would reproduce his problem

DECnet Phase IV.
OLDVAX and NEWVAX are on the same LAN.
OLDVAX and NEWVAX are in different DECnet areas.
There is no area router for the OLDVAX area.
There is an area router for the NEWVAX area.

So SET HOST from OLDVAX to NEWVAX always works (and would create a cache
entry for OLDVAX on NEWVAX).
SET HOST from NEWVAX to OLDVAX only works if there's a cache entry for

His most logical fix would therefore be to either renumber OLDVAX to be in
the same area as NEWVAX, or put up an area router for OLDVAX.