[Info-vax] LAT query

[Hans Bachner]

Rich,

Rich Jordan schrieb am 05.01.2021 um 17:50:
> Running into a novel (for me) LAT issue.  We have a site with a DS20 and a DECserver 708 with current software.  LAT is used for a couple of faxmodem connections and one management terminal that still connects that way.
> 
> We are putting an emulator in to replace the alpha.  The machine was setup offline, IP and DECNet address changed but we missed adding a service name parameter to the LAT startup so when it initially booted on the customer network, it also presented the same LAT service name as the actual Alpha.  That was quickly corrected, the emulator rebooted, and the emulator now has its separate LT service name.  The emulator and the alpha are on the same subnet/VLAN/switch with no filtering or load balancing or other possible known problem causers.

Did you configure the emulator to use the same MAC address as the 
physical DS20? This must be avoided if they are in the same LAN 
(specifically: same broadcast domain). Different DECnet addresses 
should/might hide this problem, but it's better to avoid that in the 
first place.

> Now the DECserver keeps 'losing' the alpha and the emulator as services it will connect to.  Only one of them shows up as an available service at a time, either 'alpha' or 'emu'.  You cannot connect to 'alpha' when the DECserver sees 'emu' and vice versa.  The services on both machines appear to be running normally.  One day (or for several hours) one will be available, then for reasons unknown it switches to the other.
> 
> We can bounce the decserver if that is likely to help, but I don't recall ever seeing behavior like this before, albeit with older DECservers than the 708.  Any ideas?
> 
> Thanks

Make sure LAT is started after DECnet during system startup. On the 
running system, stop LAT ($ MC LATCP SET NODE /STATE=OFF if LAT is not 
actively used by some process) and restart it with
$ @SYS$STARTUP:LAT$STARTUP

If this does not help, please post the results of the following commands:

- on both physical and emulated Alpha:
$ MC LATCP SHOW NODE
$ MC LATCP SHOW SERVICE <service-offered-by-this-node>
$ MC LATCP SHOW LINK /FULL

- on the DECserver:
Local> show node <ds20>
Local> show service <service-on-ds20>
Local> show node <emulated>
Local> show service <service-on-emulated>

Thanks  regards,
Hans.