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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter22 Configuring DHCP Features and IP Source Guard Features
Configuring IP Source Guard
If the number of ternary content addressable memory (TCAM) entries exceeds the maximum, the
CPU usage increases.
In a switch stack, if IP source guard is configured on a stack member interface and you remove the
switch configuration by entering the no switch stack-member-number provision global
configuration command, the interface static bindings are removed from the binding table. They are
not removed from the running configuration. If you again provision the switch by entering the
switch stack-member-number provision command, the binding is restored. To remove the binding
from the running configuration, you must disable IP source guard before entering the no switch
provision global configuration command. The configuration is also removed if the switch reloads
while the interface is removed from the binding table. For more information about provisioned
switches, see the “Stack Offline Configuration” section on page5-7.
Enabling IP Source Guard
Begin in privileged EXEC mode.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Specify the interface to be configured, and enter interface configuration
mode.
Step3 ip verify source
or
ip verify source port-security
Enable IP source guard with source IP address filtering.
Enable IP source guard with source IP and MAC address filtering.
Note When you enable both IP source guard and Port Security by using
the ip verify source port-security interface configuration
command, there are two caveats:
The DHCP server must support option 82, or the client is not
assigned an IP address.
The MAC address in the DHCP packet is not learned as a secure
address. The MAC address of the DHCP client is learned as a
secure address only when the switch receives non-DHCP data
traffic.
Step4 exit Return to global configuration mode.
Step5 ip source binding mac-address vlan
vlan-id ip-address inteface interface-id
Add a static IP source binding.
Enter this command for each static binding.
Step6 end Return to privileged EXEC mode.
Step7 show ip verify source [interface
interface-id]
Verify the IP source guard configuration.
Step8 show ip source binding [ip-address]
[mac-address] [dhcp-snooping | static]
[inteface interface-id] [vlan vlan-id]
Display the IP source bindings on the switch, on a specific VLAN, or on
a specific interface.
Step9 copy running-config startup-config (Optional) Save your entries in the configuration file.