On a semi regular basis the ATM interface of several models (857/877) goes down while the router doesn't really detect it being down.
A shut/no shut on the interface usually resets the condition but I wonder why the router doesn't recover all by itself.
A show dsl int atm0 reveals:
Capacity Used: 10562% 45%
Noise Margin: -9.5 dB 21.0 dB
Output Power: 12.5 dBm 1.5 dBm
All the involved routers are connected via the same ISP...