Configuring Ip Source Guard; Default Ip Source Guard Configuration; Ip Source Guard Configuration Guidelines - Cisco Catalyst 2975 Software Configuration Manual

Chapter 20 Configuring DHCP Features and IP Source Guard Features

Configuring IP Source Guard

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Default IP Source Guard Configuration

By default, IP source guard is disabled.

IP Source Guard Configuration Guidelines

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OL-19720-02
Default IP Source Guard Configuration, page 20-17
IP Source Guard Configuration Guidelines, page 20-17
Enabling IP Source Guard, page 20-18
Configuring IP Source Guard for Static Hosts, page 20-19
You can configure static IP bindings only on nonrouted ports. If you enter the ip source binding
mac-address vlan vlan-id ip-address interface interface-id global configuration command on a
routed interface, this error message appears:
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 multiple VLANs and DHCP snooping
is enabled on all the VLANs, the source IP address filter is applied on all the VLANs.
If IP source guard is enabled and you enable or disable DHCP snooping on a VLAN on the
Note
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 learned
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 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
Catalyst 2975 Switch Software Configuration Guide
Configuring IP Source Guard
20-17