AR series routers support the following preferential transmission assurances to user-defined traffic classifiers:
Assured forwarding (AF): AF ensures the low probability of dropping packets when the rate of outgoing service traffic does not exceed the minimum bandwidth. It is used for services with heavy traffic that need to be ensured.
Expedited forwarding (EF): EF is used for services that require low delay, low drop probability, ensured bandwidth, and occupying low bandwidth, for example, voice packets.
In addition to common EF queues, the device provides a special EF queue, LLQ queue with the shortest delay. LLQ provides good QoS assurance for delay-sensitive services such as VoIP services.
Best effort (BE): AR series routers allocate the remaining bandwidth that is not used by EF and AF queues to BE queues.