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 then 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.
The following table lists 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 Table 37–1.
Table 33–2 Common IPQoS Selectors
Name |
Definition |
---|---|
saddr |
Source address. |
daddr |
Destination address. |
sport |
Source port number. You can use a well-known port number, as defined in /etc/services, or a user-defined port number. |
dport |
Destination port number. |
protocol |
IP protocol number or protocol name that is assigned to the traffic flow type in /etc/protocols. |
ip_version |
Addressing style to use. Use either IPv4 or IPv6. IPv4 is the default. |
dsfield |
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 |
Priority level that is assigned to the class. For more information, see How to Define the Classes for Your QoS Policy. |
user |
Either the UNIX user ID or user name that is used when the upper-level application is executed. |
projid |
Project ID that is used when the upper-level application is executed. |
direction |
Direction of traffic flow. Value is either LOCAL_IN, LOCAL_OUT, FWD_IN, or FWD_OUT. |
Be judicious in your choice of selectors. 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.