You create filters to identify packet flows as members of a particular class. Each filter contains selectors, which define the criteria for evaluating a packet flow. The IPQoS-enabled system uses the criteria in the selectors to extract packets from a traffic flow. The IPQoS system then associates the packets with a class. For an introduction to filters, see IPQoS Filters.
Use only as many selectors as you need to extract packets for a class. The more selectors that you define, the greater the impact on IPQoS performance.
The following are the most commonly used selectors. The first five selectors represent the IPQoS 5-tuple, which the IPQoS system uses to identify packets as members of a flow. For a complete list of selectors, see Figure 3, Table 3, Filter Selectors for the IPQoS Classifier.
Source address.
Destination address.
Source port number. You can use a well-known port number, as defined in /etc/services, or a user-defined port number.
Destination port number.
IP protocol number or protocol name that is assigned to the traffic flow type in /etc/protocols.
Addressing style to use, either IPv4 (the default) or IPv6.
Contents of the DS field, that is, the DSCP. Use this selector for extracting incoming packets that are already marked with a particular DSCP.
Priority level that is assigned to the class. For more information, see Defining the Classes for Your QoS Policy.
Either the UNIX user ID or the user name that is used when the upper-level application is executed.
Project ID that is used when the upper-level application is executed.
Direction of traffic flow. Acceptable values are either LOCAL_IN, LOCAL_OUT, FWD_IN, or FWD_OUT.