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Switches and filters are defined using the filter add and filter ins commands. The filter add command syntax is:

filter add in_ports=<portlist> <filter_parameter_list> action=<redir|drop> redir_ports=<portlist>

The <filter_parameter_list> is a sequence of zero or more of the filter qualifiers as listed in the following table.

If the <filter_parameter_list> is empty, the filter add command specifies an aggregation of the traffic received on all of 

the in_ports. If the action=redir, the aggregated traffic stream is regenerated to all of the redir_ports.

If the <filter_parameter_list> contains filters, aggregation and regeneration take place as described in the previous 

paragraph. However, the filters are applied to the aggregated traffic stream before it is copied to the Monitor ports. If 

multiple filter qualifiers are specified, a packet must satisfy all of the filter qualifiers in order to be copied to the Moni-

tor ports. In other words, the filter qualifiers are combined with a logical AND condition. A logical OR condition can be 

created by using multiple filter add commands with identical port lists. 

The filter add and filter ins commands define filters but do not activate them. A subsequent filter commit or commit 

command must be executed to the filters. This mechanism enables an interrelated group of filters to be activated simul-

taneously. It also allows you to double-check your filter definitions before you activate them.

It is important to note that packets are filtered using a Content Addressable Memory or CAM. Each filter is a CAM 

entry, and the CAM is filled in the order that the filter add commands are received. Filter ins commands create filters 

in specific locations in the CAM. When a packet is processed, the first filter in the CAM that matches the packet is the 

only filter that is activated. Each packet can activate exactly zero or one filters. See Understand filter interactions

near the end of Chapter 3 for examples.

All supported filter qualifiers are shown in the following table.
Director Filter Parameters

ip_src

IPv4 address

IP source address

ip_src_mask IPv4 address mask

Mask for IP source address

ip_dst

IPv4 address

IP destination address

ip_dst_mask IPv4 address mask

Mask for IP destination address

ip_proto

Number*

Layer 4 IP protocol

l4_src_port

Port number

Layer 4 source port

l4_dst_port

Port number

Layer 4 destination port

vlan

VLAN number

VLAN

* See Appendix C for a complete list of protocol numbers. Some common protocols include:

1

ICMP

Internet Control Message Protocol

2

IGMP

Internet Group Message Protocol

6

TCP

Transmission Control Protocol

17

UDP

User Datagram Protocol

89

OSPF

Open Shortest Path First

132

SCTP

Stream Control Transmission Protocol