why sometimes a continuous ping on Cisco router suddenly pause?

[luck_zhao]

If inscribe,need to return to go on which great god can answer me? thanks!

[Flavio Miranda]

Hi There might be many reason a ping could suddenly stop. For example, interface flap, routing flap, internet flap. It would be necessary to look into logs on the router or in any device surrounding it.

[MHM Cisco World]

Some points here 

1-arp is aging which is small chance 

2-the CoPP is accpet specific rate over specific time' when this rate up this limit then packet will drop

3-the Queue is face some QoS congestion and hence QoS drop ping 

[Joseph W. Doherty]

Is the "pause" a latency jump or a lost response?

Both share many of the same possible causes, but jumps in latency might also be the targeted host was busy and since processing ping replies is usually low priority, especially on network devices, a pause might also be due to that.

Some devices might also consider a continuous stream of pings a DoS attack.