[Info-vax] Loosing all LAT connections on one machine in DECNet Network

[H Vlems]

On 15 apr, 16:08, JCamCMKRNL <jcam90... at earthlink.net> wrote:
> Answers to many of the questions:
> ---------------------------->Or is the VAX connected via AUI to the DELNI and the decserver connected 
directly to the DELNI ?
>
> Yes. In the Data Center all 5 systems, VAX & PDPs plus one DECServer
> are all connected to one DELNI.
>
> >what version of VMS do you have ?
>
> V5.5-2
>
> >Another thing to try is, from VAX:  SET HOST/LAT <vax>  -or- SET HOST/LAT <pdp>
>
> Good idea, but outgoing LAT is currently disabled. I will enable it
> and try again, but that requires Change Configuration paperwork.
>
> > MC LATCP SHOW SERVICES
>
> I will check this out if/when this problem occurs again.
>
> >What kind of VAX are you running?
>
> Micro VAX 4000-400
>
> >you mention plant, is this a Fuji site?
>
> No. We are a medical manufacturer.
>
> >Is it possible to connect a DEMPR or DESPR to the DELNI and run thinwire between the VAX and the DELNI?
>
> We have no 10-Base2 equipment or media.
>
> >Does LAT report errors?
>
> We have not experienced the problem since the last reboot, and the
> counters currently show no errors, but this was interesting from the
> MCR LATCP SHOW LINK/COUNT
> Transmit Errors -
>    Excessive Collisions:        No
>    Carrier Check Failure:       Yes
>    Short Circuit:               Yes
>    Open Circuit:                Yes
>    Frame Too Long:              Yes
>    Remote Failure To Defer:     No
>    Transmit Underrun:           Yes
>    Transmit Failure:            No
>
> >What happens if you put an AUI loopback plug in the global port of the DELNI< does the LAT service return immediately?
>
> Good suggestion. I would like to try this if/when the problem returns,
> but then the rest of the plant would loose their LAT connections to
> the PDP-11s thus affecting production, so it would not be possible.
>
> >Is LAT running on the PDP-11's, even if they run RSX-11M(+) the DECserver 200's may be used for reverse LAT. Furthermore, outbound LAT is not enabled by default.
>
> Yes, PDP-11s are running LAT.
> Yes, we have reverse LAT ports on PDP-11 and VAX.
> No, outbound LAT is not enabled on any hosts.
>
> >It doesn't have to be hardware. DECnet to/from the VAX still seems to work and - I assume - it is using the same ethernet interface.
>
> That is correct, same interface.
>
> >Looking at the DECserver counters may also provide some more insight: SHOW COUNTER, SHOW NODE {vax} COUNT, SHOW SERVICE {vax}
>
> I dont think the counters on the DECServers will yeild much
> information, because all DECServers throughout the plant loose their
> LAT connections to the VAX when this happens.
>
> -----------------------
> I will keep you all informed.
> I appreciate all of your input.
>
> Jeff Cameron

Jeff, you write that "the counters show no errors, but this was
interesting from the MCR LATCP SHOW LINK/COUNT ...etc"
What counters show no errors?
If the DECnet (LINE!) counters on the VAX are zero while at the same
time the LAT link status parameters indicate some sort of problem
then:
(a) there may a problem with the ethernet interface in the VAX
(b) there may be a problem with the DELNI
(c) the DELNI's transceiver is at fault
There is clearly something wrong on the wire that bothers LAT but
seems to leave DECnet alone.
My guess would be that the transceiver on the DELNI is having
problems.
Both the VAX and the DELNI are built for eternity, an H4005 is not in
the same league (my *humble* opinion).
I hope it's an H4005 or a late model H4000: these share the same wire
tap assembly. Just replace the transceiver body and check.
If it is an older H4000, connect a known good (I hesitate to write
"new") H4005 and connect the DELNI to this replacement device.
Hans

PS
The transceiver on the DELNI wasn't replaced recently was it?

PPS
You wrote that there is no 10BASE2 gear available. Is it possible to
use RJ45 transceivers (enable heartbeat), a low speed UTP switch or
hub with an AUI port on it?

PPPS
The reason I thought of Fuji is that they also use(d) a similar set up
for their plants.