  Problems with third-party LAT terminal servers? 
 The Question is:
 
A previously independent network (with 16 nodes
and unknown protocols) was brought onto our
network. (I know, I know, stop laughing now...)
This black box network, once connected to our
large multi-protocol network, caused an existing
and previously operational LAT/VAX/terminal
server-type network to experience intermittent
operation (all terminal server/LAT connex. would
get terminated with "illegal circuit" indications
at the terminals every 1 to 3 minutes). The
terminal servers are a combination of Xyplex and
Cabletron ETSMIM cards. A NGC protocol sniffer
shows the VAX machine issuing a disconnect
because of an illegal format, with a VAX source
circuit id of 0000. Note that people using
TCP/IP to connect to the same resource experience
no problems (using "Reflections"? software).
What might be the various reason(s)/cause(s)
for LAT to terminate ALL the terminal sessions?
(note that the users can connect right back to
the vax again, but then they get kicked off
within minutes). I read as much as I can find
about the lat protocol, but I haven't found
"troubleshooting" type of info, just "theory of
operation" type info. Thanks!!
 
 
 The Answer is:
 
  TCP/IP is an entirely separate protocol from LAT, only those problems in
  common network hardware, with bridges, or resulting from network congestion
  will tend to affect both protocols.
 
  This question is well beyond the purvue of the OpenVMS Wizard, and this
  will require the assistance of the customer support center to resolve.
  It would appear that there are network problems or potentially problems
  with the LAT implementation on the Xyplex or Cabletron servers, or there
  are problems induced by other hardware present on the network.
 
