Class maps are used to create classification templates that are later used in policy maps in which QoS mechanisms are bound to classes.
Routers can be configured with a large number of class maps (currently limited to 256).
You can create a class map by using the class-map global configuration command. Class maps are identified by case-sensitive names. Each class map contains one or more conditions that determine if the packet belongs to the class.
There are two ways of processing conditions when there is more than one condition in a class map:
■ Match all: This is the default match strategy. All conditions have to be met to bind a packet to the class.
■ Match any: At least one condition has to be met to bind the packet to the class.
• Match-any requires at least one condition to return a positive answer. If no condition is met, the class map will return a "no match" result.
The figure illustrates the process of determining if a packet belongs to a class (match) or not (no match).
The process goes through the list of conditions and returns the following:
■ A "match" result if one of the conditions is met and the match-any strategy is used
■ A "match" result if all conditions are met and the match-all strategy is used
■ A "no match" result if none of the conditions are met
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