How does LLQ ensure that voice traffic is always expedited?
A.
LLQ adds WRED to CBWFQ. This allows delay-sensitive data such as voice to be dequeued
and sent first.
B.
LLQ uses CBWFQ to prioritize voice traffic and by dequeuing the voice packets so they can be
handled first.
C.
The strict priority queue has a higher weight than the queues in CBWFQ. This weight allows the
delay-sensitive data such as voice to be dequeued and sent first.
D.
The LLQ strict priority queue allows delay-sensitive data such as voice to be dequeued and
sent first (before packets in other queues are dequeued), giving delay-sensitive data preferential
treatment over other traffic.
Explanation:
Without Low Latency Queueing, CBWFQ provides weighted fair queueing based on
defined classes with no strict priority queue available for real-time traffic. This scheme poses
problems for voice traffic that is largely intolerant of delay, especially variation in delay. For voice
traffic, variations in delay introduce irregularities of transmission manifesting as jitter in the heard
conversation. The Low Latency Queueing feature provides strict priority queueing for CBWFQ,
reducing jitter in voice conversations. Configured by the priority command, Low Latency Queueing
enables use of a single, strict priority queue within CBWFQ at the class level, allowing you to
direct traffic belonging to a class to the CBWFQ strict priority queue.
http://www.cisco.com/en/US/docs/ios/12_0t/12_0t7/feature/guide/pqcbwfq.html