the clock should come from the line, yes. If this are'nt working you rably have errors on the line or some other Problems from your provider. The only thing i have in mind what can need you to configure internal clocking is when you put 2 routers back-2-back.
Have you checked the error counters with sh int and sh controller? Do you see any problems there?
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...