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22-18
Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02
Chapter 22 Configuring DHCP Features and IP Source Guard
Configuring IP Source Guard
• When configuring IP source guard on interfaces on which a private VLAN is configured, port
security is not supported.
• IP source guard is not supported on EtherChannels.
• You can enable this feature when IEEE 802.1x port-based authentication is enabled.
• If the number of hardware entries exceeds the maximum available, the CPU usage increases.
Enabling IP Source Guard
Beginning in privileged EXEC mode, follow these steps to enable and configure IP source guard on an
interface.
To disable IP source guard with source IP address filtering, use the no ip verify source interface
configuration command.
To delete a static IP source binding entry, use the no ip source global configuration command.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Specify the interface to be configured, and enter interface configuration
mode.
Step 3
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.
Step 4
exit Return to global configuration mode.
Step 5
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.
Step 6
end Return to privileged EXEC mode.
Step 7
show ip verify source [interface
interface-id]
Display the IP source guard configuration for all interfaces or for a
specific interface.
Step 8
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.
Step 9
copy running-config startup-config (Optional) Save your entries in the configuration file.