CBWFQ versus dWRED

tgurney · ‎07-22-2009

Basically, the way I read the difference between these two is:

dWRED moves drop probability into the router WAN interface queueing decision process, where CBWFQ simply states a BW reservation for the entire class and drop probability is striclty handled then in the carrier cloud.

CBWFQ seems to be the desired or most used mechanism.

dWRED requires a knowledge of queue size in advance.

Joseph W. Doherty · ‎07-22-2009

I would consider the difference between the two: CBWFQ manages scheduling when dequeuing packets, while WRED manages drops of queued packets. Since they deal with congestion (queued packets) differently, they can be used independently or used together. Both aren't concerned with what happens later downstream (e.g. within carrier cloud), but what happens at some point where packets are queued.

chinkevi_2 · ‎07-22-2009

one is congestion management feature by selective and weighted dropping packet, and one is user defined classification and queue management feature, which also include RED in queue.

I don't think you should compare them side by side.