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QoS clear documentation


I'm missing a QoS document explaining clearly WHEN particular QoS tools (queuing, policing, shaping) are applied, what happens if configured but no congestion occurs on the line, when exactly they start to be active in a case a congestion comes.

Another topic missing is hieararchical (nested) polices.

I've seen many QoS documents but none of them descibed those topics in sufficient details.



New Member

Re: QoS clear documentation

Hi, Milan -

Thank you for your posting. You have raised several issues.

First, as to available QoS documentation, perhaps the most comprehensive document is the Cisco IOS Quality of Service Solutions Configuration Guide, Release 12.4T, at

This guide contains the majority of the available features, although there are a few that are available only on specific trains (for example, on the XE or SR trains). For the most part, though, the 12.4T CG is the superset, with the other trains being subsets.

Second, regarding hierarchical (nested) policies, these kinds of policies (policy maps) form the foundation for many QoS features. The main source (to date) of information about hierarchical policy maps is contained in the single-source module called “Applying QoS Features Using the MQC,” at

However, other features also involve hierarchical policies, such as are found in the links below:

The above resources may not specifically address what you are looking for, but they help to illustrate the roles that hierarchical policies play.

Third, we are aware that our document set as currently structured does not always address the larger topic of when to enable certain features. That is specialized design-level information such as is typically addressed in white papers and TAC documentation. Because of the many variables involved in permutations of product interactions and network designs, such information would be impossible to include in our document set.

Finally, if you can summarize the types of equipment you are working with, the Cisco IOS releases, and enough of the network design to highlight a specific QoS implementation objective, we suggest that you present that picture to the technical side of this forum, in addition to following up with TAC. If it becomes apparent that there is additional information we should be adding to our documents, we will ensure that your suggestions reach the right team so that appropriate actions may be taken.