[c-nsp] VIP with no PAs

[Bill Wichers]

> I'm having yet another recurrence of strange VIP problems in our 7513.
> This VIP seems to fail every 3-6 months with cache memory parity errors.
> This time it only last two months before it started crashing. Anyway, I
> opened up another case with TAC and the engineer suggested that I pull
> the VIP, remove the port adapters, and reinsert the VIP and then monitor
> it for a while. I've always been under the impression that you weren't
> supposed to insert a VIP that had no PAs installed.
>
> I'm giving him the benefit of the doubt but this still worries me a
> bit. Does that sound like good or bad advice?

VIPs with no PAs installed aren't supported, but there might be some
undocumented test mode or something like that. Can't say I've ever tried
to insert one without any PAs (it's not a very useful configuration :-).

If you're getting VIP crashes I'd bet you have bad RAM, or maybe a bad bus
interface. I've seen both before. Easiest solution is to just replace the
entire VIP. The RAM problem specifically I've seen result in VIP crashes
in the "every few months" timeframe, and the time between crashes
shortened over time. I had a problem just like that once before that we
though was a bad link at first (it was causing BGP flaps), but eventually
traced it back to a bad SDRAM on the VIP.

> [As a side note, after analyzing the crash files, he really has no idea
> what's causing the thing to crash. He also wants me to replace our RSP
> to see if that stabilizes the VIP, so I'll be coming in again in the wee
> hours tomorrow morning to take care of that.]

The RSP suggesting seems odd to me. Do you have any other VIPs in the
chassis that are NOT showing the problem?

     -Bill


*****************************
Waveform Technology
Systems Engineer