[c-nsp] Output drops on PPP multilink int

[Church, Charles]

Anyone,
 
    Seeing lots of output drops on ppp multilink interfaces across our
network, all multiple T1s, on 2600s through 3800 routers.  The
underlying T1 serial ints don't have many drops (maybe 0.1% of those
found on the multilink int worst case).  Any idea what would cause drops
on the interface?  There is no QOS or anything like that on the mu2 int,
just an inbound ACL.  Google search didn't really turn up anything too
useful.  CPU and memory on the routers look pretty good.  T1s seem
pretty clean, the couple routers I watched closely didn't have any T1
errors during the time frames when drops where occuring.  All are
running recent 12.3 or 12.4 mainline releases.  Utilization on the
multilink interface was low (under 25%), at least according to the 30
second load interval.
 
Thanks,
 
Chuck