[c-nsp] DS3 problem on PA-T3

[Robert Boyle]

At 11:56 AM 10/1/2008, Jay Nakamura wrote:
>It looks like Opti-3 have "Long" and "Short" option for LBO on the DS3
>interface.  I am going to make sure Verizon set it to short since the coax
>is only about 15' long.

Even with short LBO, we still need the attenuators sometimes. Look 
for LCV errors.

>I don't have any attenuators handy to try that out.  I did however, changed
>the DSU mode to Kentrox and errors have gone away for the last hour.  I
>didn't think that really mattered if you were doing full DS3.

It does matter. Verizon does have a lot of ADC/Kentrox DSUs 
connecting via HSSI to their old frame relay switches in their COs. 
Be careful of a nasty bug we found which will hang the router on boot 
if all of the following are true:

1. You have a PA-T3 or PA-2T3
2. You have dsu mode 2? (Kentrox mode whatever that is - I don't have 
time to look at the config at the moment)
3. A T3 is connected (unplug the T3 RECV and it will boot fine)
4. You reboot (soft or hard)

The router will hang right after it lists the RAM during the POST. 
The problem is with the microcode initialization for the DS3 chip 
when using Kentrox mode and only if there is carrier detected. They 
finally fixed this, but it is late in the 12.3 train and I don't 
think they backported it to 12.2. This is a nasty surprise when you 
reboot the router at a remote POP at 3AM. Just test for this and if 
you have the bug, let me know and I'll track down the bug ID in my 
archives. This problem was reproducible on any 72XX router with any 
PA-T3 or PA-2T3(+) card.

-Robert



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