Congestion Management and Queuing - LLQ

LLQ (Low Latency Queuing) - offers all of the benefits of CBWFQ, but with the ability to offer low delay and jitter queues for supporing VoIP/ToIP. As with CBWFQ all traffic not identified using class-maps is assigned to the default-class, which uses all remaining available bandwith. Default-class can use FIFO or WFQ, also with WRED.

Strict priority queues enable low-delay transmission of real-time data, the queue is policed, this prevents starvation of the other queues.

Configuration of LLQ follows the same methods as CBFWQ, an additional 'priority' command is used to specify strict-priority queues.

E.g.
policy-map enterprise_qos
class voice
priority 50
class business
bandwith 200
class class-default
fair-queue

The policy above offers strict-priority queue for voice class, with bandwidth guarantee of 50Kb/sec, business class is guaranteed 200Kb/sec using CBWFQ.