Classes

A class specification begins with the keyword class, followed by an optional list of parameters, in parentheses, zero or more selectors (selectors are typically if constructs, see section 2.6), and an optional list of items attached to the class, in curly braces.

Examples:

// clear TOS byte of all packets with EF and no ECN bits set

dsmark(set_tc_index) {
    class (0x2e << 2, mask 0);
}

egress {
    class (<$one>)
        if ip_dst == 10.0.0.1;
    class (<$two>)
        if ip_dst == 10.0.0.2;
    class (<$three>)
        if 1;

    prio {
        $one = class (1);
        $two = class (2);
        $three = class (3);
    }
}

The number of a class is usually automatically assigned. It can be explicitly set by including it among the parameters, e.g.

class (1) ...;