Configuration - Cisco Catalyst 2000 Configuration Handbook

Configuration

By configuring protocol filtering on a switch, you prevent the port from flooding traffic
of that type received from other ports in the VLAN out the given port. This can be use-
ful in controlling traffic from clients within the same VLAN running different and "chat-
ty" protocols. To configure protocol filtering, use the following steps.
Enable protocol filtering for the switch:
1.
(global) protocol-filter
Protocol filtering is disabled by default. For the ports to control the traffic, you must
first enable protocol filtering for the switch. After enabling the process, you can set
up the ports to react to a given protocol.
Enable protocol filtering on an access port:
2.
(interface) switchport protocol {ip | ipx | group} {on | off | auto}
For each port on which you want to control traffic, you must specify the protocol and
how traffic is to be handled. The protocol option specifies the given type of protocol.
You can choose from among the following options: ip (IP), ipx (IPX), and group
(AppleTalk, DECnet, and Banyan VINES). The options specify how traffic is to be han-
dled. The option on specifies that a port is to receive traffic for the protocol and forward
flood traffic for that protocol. The option off specifies that the port cannot receive or
flood traffic for a given protocol. The option auto indicates that the port will not flood
traffic for a given protocol until it first receives a packet of that protocol on the port.
Table 11-1 lists the default actions if the ports are not configured.
Verification
To verify the configuration of protocol filtering, use the following commands:
(privileged) show protocol-filtering
OR
(privileged) show protocol-filtering interface {type slot/port}
These show commands display the configuration for the specified ports. In IOS, the com-
mand show protocol-filtering without any port designations will show only ports that
have at least one protocol that is in the nondefault mode.
Table 11-1 Protocol Filtering Defaults
Protocol
IP
IPX
Group
Chapter 11: Controlling Traffic and Switch Access 171
Mode
on
auto
auto