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Cisco IE 3010 Switch Software Configuration Guide
OL-23145-01
Chapter 21 Configuring DHCP Features and IP Source Guard Features
Configuring IP Source Guard
Static IP source binding can only be configured on switch port.
• When IP source guard with source IP filtering is enabled on an interface, DHCP snooping must be
enabled on the access VLAN for that interface.
• If you are enabling IP source guard on a trunk interface with m ultiple VLANs and DHCP snooping
is enabled on all the VLANs, the source IP address filter is applied on all the VLANs.
Note If IP source guard is enabled and you enable or disable DHCP snooping on a VLAN on the
trunk interface, the switch might not properly filter traffic.
• If you enable IP source guard with source IP and MAC address filtering, DHCP snooping and port
security must be enabled on the interface. You must also enter the ip dhcp snooping information
option global configuration command and ensure that the DHCP server supports option 82. When
IP source guard is enabled with MAC address filtering, the DHCP host MAC address is not learn ed
until the host is granted a lease. When forwarding packets from the server to the host, DHCP
snooping uses option-82 data to identify the host port.
• 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 802.1x port-based authentication is enabled.
• If the number of ternary content addressabl e memory (TCAM) entries exceeds the maximum, t he
CPU usage increases.
Enabling IP Source Guard
Begin in privileged EXEC mode.
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.