Low Latency Queuing

A Low Latency Queue (LLQ) is a non-configurable strict priority queue. LLQs are designed to guard against:

• Packet loss
• Delay
• Jitter

LLQ hardware resources can not be configured, but a policy can be configured for a CoS that is mapped to an LLQ. In this way, traffic associated with high value real-time voice or video packets can be mapped to an LLQ. The LLQ priority will determine when mapped traffic will be serviced relative to other traffic. For example, S-Series queues 0, 9, and 10 are LLQs. If a voice policy is mapped to a CoS with a TxQ reference that is in turn mapped to queue 9, this voice traffic will be serviced as soon as queue 10 is empty and will continue to be serviced ahead of any lower priority queue until there is no traffic left in queue 9.

LLQs are hardware dependent. Use the show cos port-config txq command to display LLQs for a given module.