Cisco IE-3000-8TC User Manual

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Cisco IE 3000 Switch Software Configuration Guide
OL-13018-03
Chapter 23 Configuring DHCP Features and IP Source Guard
Configuring IP Source Guard
• 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.
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.
• When IP source guard with source IP and MAC address filtering is enabled, 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 the 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 IEEE 802.1x port-based authentication is enabled.
• If the number of ternary content addressable memory (TCAM) 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.
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.

Cisco IE-3000-8TC Specifications

General

Brand	Cisco
Model	IE-3000-8TC
Category	Switch
Language	English