The Question is:
We have a variety of VMS systems that access a variety of LAT terminal servers
to talk to printers, process equipment, etc... This is all spread over a
couple of square miles.
What I'd like to do is obtain the hardware (MAC) addresses of the terminal
servers that these VMS systems connect to for the purposes of inventorying and
Since the VMS systems do talk to these terminal servers, presumably the MAC
address is there someplace. How can I get to it?
The Answer is :
Certain MOP-compliant devices can provide various configuration
and maintenance information via the MOP SYSID message -- please
see the DECnet MOP specifications (pointer in the FAQ) for details
on the MOP SYSID, and please also see DECnet-related documentation
on the MOP configurator surveillance.
If the network devices do not provide MOP SYSID messages, then the
detection and configuration will be rather more difficult. This
could involve monitoring LAT traffic for addresses using typical
promiscuous mode network monitoring, of course. Tools such as
[NETMON]MONLAT.MAR (on the OpenVMS Freeware) may be of interest,
as well as various commercial network monitoring packages.
At the LAT protocol level, the terminal server devices are the
initiators of an asymmetric betwork connections, and these devices
have to be expressly configured to permit "reverse LAT" connections;
connections from the host to the terminal server. In other words,
the default LAT configuration has the terminal server detecting and
connecting to the host(s), and not the reverse.