AI, ML, Development + Cisco Learning Blog Learning about Machine Learning, Artificial Intelligence, related devlopment topics and formerly Routing and Switching, Datacenter, Security and other topics, CCIE #23664, Frank Wagner

9. November 2008

multiple LLQ Low Latency Queues / bandwith (remaining) percent

Filed under: QoS — ocsic @ 11:26

LLQ means priority a queue, to forward voice and video traffic before all other traffic.

If you have multiple LLQ queues, the difference between the single and multiple queue configuration is, that if you have at least two priority queues, both get policed. So if configured in a single police-map command, you will always policed the traffic at a maximum rate. Even if more bandwidth will be available, in case one queue fills up and the other still is not yet. The traffic will strictly be policed at the maximum rate.

The bandwidth percent gives the option to reserve a percentage of a link, also in case the link speed will change in the future. It will be calculated dependent on the actual link speed for the interface. This is changeable with the „bandwidth“ command on the interface.

The bandwidth remaining percent gives the option, to configure a remaining bandwidth on the actual link. If the link for example has a bandwidth of 1000 kbps and there is already different LLQ’s (100,200), then this is added to 300 kbps being already reserved. „max reserved-bandwidth“ will be per default 75% on an interface, which is 750 kpbs. So if you configure a reservation from the remaining percent, it will be calculated from

750 kbps

-300 kbps


450 kbps.

So if you configure „bandwidth remaining percent 50“ you will get 225 kbps from the bandwidth of the interface.


Cisco Qos, Exam Certification Guide, Second Edition, Wendell Odom

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