Configuring LLQ – Low Latency Queuing
Well, since I covered the CBWFQ in my last post I think it’s only natural I jump into the configuration of yet another QoS configuration Low Latency Queuing or LLQ. LLQ simply builds off the CBWFQ, let’s look at the configuration from my last post concerning CBWFQ:
Now let’s configure LLQ:
See the difference? Notice the priority keyword, that is what configures LLQ. Not too complicated right? Now what does this priority command really do for us, well it creates a low latency queue for traffic that needs to be transmitted before other type of data. So if there is data in the low latency queue when does the data in the other queue’s get transmitted, easy when the low latency queue is empty or when the low latency queue exceeds its specified amount of bandwidth. The low latency queue is also policed by the bandwidth we have allocated it. If the low latency queue ever exceeds the amount of bandwidth it has been allocated it will drop the packet and move to another queue.
Below is a flow chart from the QoS Exam Guide explaining how the LLQ works: