Filter Blocks
Filter Blocks
A filter defines a traffic class. A traffic class is the set of all possible packets that match the filter. The filter keyword marks the start of a filter block definition. The string immediately following the filter keyword is the name of the block.
The
filter filtername { filter_attributes
}
In each filter specify one or more attributes (traffic selection criteria), such as source address or destination transport port number, that define the traffic class.An outbound packet matches a filter if and only if it matches all of the attributes specified in the filter. Thus, filter attributes are AND conditions.
IMPORTANT You do not have to specify every possible attribute for a filter. Omitted attributes are considered “don’t cares”. You must however, specify at least one attribute. Filters with no attributes set will cause an error message to be generated.
You can use more than one filter to define a class of traffic that you want to regulate. For example, to regulate all traffic being sent to different hosts that are not consecutively numbered (for example 1.2.3.4 and 1.2.3.6 but not 1.2.3.5), define one filter for each address, then assign both filters to the same policy.
Packets that do match any specified filter are sent out using a default policy. This policy is referred to as the implicit default flow. This policy adheres to: a res (reservation) bandwidth value of 80Kbps; no max (maximum) burst bandwidth value; and no DSCP or VLAN priority marking.
Filter Attributes
Filter blocks can contain any combination of the attributes described in this section, including no attributes, except where otherwise noted. Attributes cannot be specified more than once in a filter.
The following rules apply to filter blocks:
•No default values are used in the syntax below.
•Valid IP addresses must be specified.
64 | Chapter 4 |