Odd 7206 VXR crash

Last night we swaped a 7206-VXR in for our aging 7206. We'd had
the VXR for a few weeks, it had been powered up for a couple of
weeks and tested some, though not of course moving actual traffic.
At any rate, we hadn't seen any glitches.

So we pulled the PAs from the 7206, installed them in the VXR,
booted, watched it for a while and went home. Half an hour later
we were off the net. Since it was about 2 a.m. and I was in no
shape to troubleshoot, I went in, swapped the cards back into the
old router, booted it, and went home.

Here's the strange thing: When I got there, there were _no_ lights
on the VXR --- not even the power LED. There is no indication of
anything going wrong in the console log (we use the serial console
to manage our routers, and conserver to log console activity). The
power switch was on and the power cable firmly connected on both
ends before we left, and no gremlins broke into our machine room
in the mean time. No other machine experienced a power loss.

Does anyone have any idea where I should even start
troubleshooting this?

 

[...newly installed 7206VXR failed...]

: Here's the strange thing: When I got there, there were _no_ lights
: on the VXR --- not even the power LED. There is no indication of
: anything going wrong in the console log (we use the serial console
: to manage our routers, and conserver to log console activity). The
: power switch was on and the power cable firmly connected on both
: ends before we left, and no gremlins broke into our machine room
: in the mean time. No other machine experienced a power loss.

: Does anyone have any idea where I should even start
: troubleshooting this?

I had a VXR that showed similar symptoms. The power LED would light up,
when power was applied, and then shut off a few seconds later.
Reseating the I/O and CPU boards solved the problem, and it has been
running for over a year since then.

I've aways assumed the power supply was waiting for a signal from
the I/O card and/or CPU and would shutdown when it never arrived.

 

That's actually not very similar --- our VXR booted, detected all it's
interfaces, and was in operation, happily routing packets for roughly
an hour before suddenly shutting itself off. We had had it powered
up for two weeks solid prior to placing it in service --- but it wasn't
under load then, and it had three fewer port adapters.

People in private mail have suggested that the p/s is old and/or
flakey and having trouble with the load of four PAs that it didn't
show without that load, and/or the contacts need cleaning. I'm
going to try cleaning the contacts. I'm also trying to borrow some
spare PAs from friends colleagues around Boston so we can test it
under load without actually placing it in service. And next time I
place it in service, it will have two power supplies installed.