[nsp] DSL - PPPoE sessions dropping

[Brian Lehigh]

Hello all,
We have been experiencing an odd problem which is causing a tremendous
amount of frustration with our DSL customer base.  We have about 1300
DSL customers coming into a 7206VXR NPE-400 via a DS3 to the local
Telco's ATM network.  Now, up until about a month or so ago everything
was going great.  Recently, we have begun seeing customers' PPPoE
sessions dropping and coming right back on.
Initially, we had a problem with the brand of CPE we were using where
the modems would lock-up if the PPPoE session was dropped unexpectedly,
causing our customers to have to power-cycle their modems several times
a day.  This issue has been resolved, however, we are still seeing the
sessions drop and then re-establish.  Sometimes it's not for days,
sometimes it's several times a day.  We have verified these modems
remain on with constant traffic being passed.  For some reason something
is causing the session to be dropped.  We are not seeing legitimate PADT
packets so something makes me think something is occurring in the ATM
cloud that is causing this to occur.
Have any of you ever seen anything like this before?  Any suggestions?
Any debugging that you think we could do to help narrow this down?
As it stands, the ATM DS3 is stable and running clean.  We are not
getting much support from the local Telco.  They are basically telling
us that the circuit is clean and they don't see any errors and have told
us the problem is with PPPoE.
What do you guys think?
 
Thanks,
 
-Brian