Qos utilization on the interface

[masenyam53796]

CBWFQ is configured on the router and the link performs well with no congestion. Will the router still utilize the CBWFQ? I remember attending qos training and learned that under normal condition the router utilizes default queuing method which is FIFO. And only use CBWFQ when there's overutilization on the interface. I am not sure if I remember things correctly from that training because its long time ago, say 15 to 10 years. I guess I am asking whether the router will start to use the qos immediately even when there's no congestion or not.

[Joseph W. Doherty · Accepted solution]

"CBWFQ is configured on the router and the link performs well with no congestion."

Laugh, and how do you know the link is performing well not because there's CBWFQ?

I define congestion when a packet arrives for egress but cannot immediately be transmitted.  How do you define congestion?

As to the basic question of when is CBWFQ actually actively, doing something, that depends on the CBWFQ configuration, and possibly other configuration settings not part of CBWFQ.  For example, marking or policing probably don't require interface congestion (even of the kind the way I define), and CBWFQ only comes into play when an interface hardware FIFO queue (tx-ring) overflows.  (NB: the latter not to be confuse with a software FIFO queue.)

[masenyam53796 · Accepted solution]

Thanks for prompt reply. I am satisfied with the reply. thank you.

[Joseph W. Doherty]

Just "satisfied"?

If you were looking or hoping for a better answer, feel free to further inquire.