# 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 |