QoS - Input queue question
I was going over QoS again and there is something that is bugging me. How can an input queue on an interface get congested using the following example out of the Vol 1 book? R6 pings R1 and the interface on R1 drops traffic on the input queue.
R6#ping 126.96.36.199 repeat 1000000 timeout 0 size 1000
Sureley R6 can only transmit at the same speed as R1 can receieve so I dont see a scenario where R6 can overrun the interface? Traffic on R1 should be pulled off the Rx ring and transmitted to the backplane as fast as its sent when we use hardware switching. There should never be a need for the Rx-ring to use the input queue unless we are not using CEF and the routers CPU is busy. Am I correct?