rando@skipper.dfrf.nasa.gov (Randy Brumbaugh) (07/01/89)
We are having mysterious network problems, and I am hoping someone has had
a similar problem (or, actually I hope they have a solution).
Every morning for the past 5 days our network has been dead. By dead, I mean
that no communication is happening on the cable. Our Sun 3/60's have MANY
messages "transmitter frozen -- resetting" on the console. Our 3/280 repeats
"iebark reset" over and over, and our Masscomp crashes after reporting
something about ring buffer overflows. Our Kinetics Fastpath 4 flashes both
LEDs at the same time. When we tried to bring up our LANalyzer to see what
was going on, it couldn't even initialize the ethernet interface board
(it works fine after things are fixed).
Our network is connected to the facility backbone network through a DEC
LAN Bridge 100. This critter normally sends out about 1 packet a second
to test for loops. You can watch this happen by observing the LEDs on the
unit. When we get this crash, the LED indicating traffic on our side of the
bridge stays dark. Everything on the other side seems to communicate fine.
Using something less than the scientific method we discovered that we can
cure the problem simply by cycling power on our DELNI (DEC version of an
ethernet transciever fan-out box). When it power is restored to it, everything
is fine.
Soon, it started happening more than just early in the morning -- today it
happened three times before lunch. The DELNI trick worked every time. Twice
we had the LANalyzer running during the crash and caught some bad packets. I
don't know if these were a symptom or a cause.
Anyway, I am baffled -- I thought a DELNI was just a collection of op-amps
and resisitors? I don't see how it could get into a bad state if it can't have
ANY state! But if the problem is somewhere else, why does cycling power on the
unit help?
I have heard that certain LAN Bridge PROM revs and Fastpaths are bad mixes. Is this
what happens? What about if a transmitter is babbling? Would it cause these
symptoms? Any help would be appreciated?
Randy Brumbaugh
PRC / NASA Ames-Dryden
rando@skipper.dfrf.nasa.gov
(805) 258-3311 x 5177