Filters are used to assign the incoming packets to one of the classes for the queuing discipline.
This is done when the enqueue function of the queuing discipline is called.
Filters are kept in filter lists, either per class or per queuing discipline based on the queuing discipline.
Filter lists are ordered by the priority and are keyed by the protocols for which they apply.
Filters may have internal elements that are referenced by 32-bit handles.
Filters are handled by the following operations.
- classify, init, destroy, get, put, change, delete, walk, dump.
Types of filters
- Generic Filters - E.g. Routing table based classifiers
- Specific Filters - E.g. RSVP classifiers, u32 classifiers and recently tc_index classifiers that are used for classifying aggregates