Assured Forwarding

Assured Forwarding (AF) is a mechanism for assurance of delivery, given a defined rate.

In case of congestion, traffic that exceeds the rate have a higher probability of being dropped.

The four AF classes have the same priority. For each class, packets are given a drop probability.

Drop probability	Class 1	Class 2	Class 3	Class 4
Low	AF11	AF21	AF31	AF41
Medium	AF12	AF22	AF32	AF42
High	AF13	AF23	AF33	AF43