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Configuring IP Source Guard
How to Configure IP Source Guard
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 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.
How to Configure IP Source Guard
Enabling IP Source Guard
Command
Purpose
1.
configure terminal
Enters global configuration mode.
2.
interface
interface-id
Specifies the interface to be configured, and enters interface
configuration mode.
3.
ip verify source
or
ip verify source port-security
Enables IPSG with source IP address filtering.
Enables IPSG with source IP and MAC address filtering.
Note:
When you enable both IPSG 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.
Summary of Contents for IE 4000
Page 12: ...8 Configuration Overview Default Settings After Initial Switch Configuration ...
Page 52: ...48 Configuring Interfaces Monitoring and Maintaining the Interfaces ...
Page 108: ...104 Configuring Switch Clusters Additional References ...
Page 128: ...124 Performing Switch Administration Additional References ...
Page 130: ...126 Configuring PTP ...
Page 140: ...136 Configuring CIP Additional References ...
Page 146: ...142 Configuring SDM Templates Configuration Examples for Configuring SDM Templates ...
Page 192: ...188 Configuring Switch Based Authentication Additional References ...
Page 244: ...240 Configuring IEEE 802 1x Port Based Authentication Additional References ...
Page 298: ...294 Configuring VLANs Additional References ...
Page 336: ...332 Configuring STP Additional References ...
Page 408: ...404 Configuring DHCP Additional References ...
Page 450: ...446 Configuring IGMP Snooping and MVR Additional References ...
Page 490: ...486 Configuring SPAN and RSPAN Additional References ...
Page 502: ...498 Configuring Layer 2 NAT ...
Page 770: ...766 Configuring IPv6 MLD Snooping Related Documents ...
Page 930: ...926 Configuring IP Unicast Routing Related Documents ...
Page 976: ...972 Configuring Cisco IOS IP SLAs Operations Additional References ...
Page 978: ...974 Dying Gasp ...
Page 990: ...986 Configuring Enhanced Object Tracking Monitoring Enhanced Object Tracking ...
Page 994: ...990 Configuring MODBUS TCP Displaying MODBUS TCP Information ...
Page 996: ...992 Ethernet CFM ...
Page 1066: ...1062 Using an SD Card SD Card Alarms ...