[c-nsp] Correct debug command on Cisco 7206VXR to analyze PPP sessions for just one VC

[Frank Bulk]

We have an issue with our transport network where certain customer's ATM
traffic doesn't seem to be flowing smoothly between the customer modem and
our central broadband aggregator, the Cisco 7206VXR.  Specifically, some
PPPoA sessions aren't being established.  Our transport network vendor has
asked us to look at the PPP traffic for just one VC, but it looks like the
'debug ppp' commands don't give us that level of granularity.  If I turn it
on, as I have in the past, the flood of debug traffic will swamp the console
and only a power recycle will recover the unit for us (and disconnect 2000+
customers for several minutes)/

We can run the 'debug atm packet interface atm X/Y.Z vc A/B' command, but
the output too low-level for us to use.

Is there any other way on the Cisco 7206VXR to look at the PPP traffic on a
certain VC?  We're using version 12.2(26).

Regards,

Frank