Common IPSG Operations : Configuring IPSG Based on DHCP Snooping Dynamic Binding

IPSG based on a DHCP snooping dynamic binding table filters IP packets received by untrusted interfaces, to prevent malicious hosts from stealing authorized hosts' IP addresses to access the network without permission. IPSG based on a dynamic binding table is applicable to the LAN where a large number of hosts reside and the hosts obtain IP addresses through DHCP. The configuration procedure is as follows:

1. Configure DHCP snooping so that a DHCP snooping dynamic binding table is generated.
   1. Run the dhcp enable command in the system view to enable DHCP globally.
   2. Run the dhcp snooping enable command in the system view to enable DHCP snooping globally.
   3. Run the dhcp snooping enable command in the interface or VLAN view to enable DHCP snooping on the interface or in the VLAN.
   4. Run the dhcp snooping trusted command in the interface view or the dhcp snooping trusted interface interface-type interface-number command in the VLAN view to configure a trusted interface.

      The device directly forwards the IP packets received by the trusted interface without checking them against the binding entry.

2. Run the ip source check user-bind enable command in the interface or VLAN view to enable IPSG.

The following example shows how to configure IPSG based on DHCP snooping dynamic binding table:

# Configure DHCP snooping, specify GE0/0/1 as a trusted interface, and enable IPSG on GE1/0/2.

<HUAWEI> system-view
[HUAWEI] dhcp enable
[HUAWEI] dhcp snooping enable
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] dhcp snooping trusted
[HUAWEI-GigabitEthernet0/0/1] quit
[HUAWEI] interface gigabitethernet 1/0/2
[HUAWEI-GigabitEthernet1/0/2] dhcp snooping enable
[HUAWEI-GigabitEthernet1/0/2] ip source check user-bind enable

# Configure DHCP snooping, specify GE0/0/1 as a trusted interface, and enable IPSG in VLAN 10.

<HUAWEI> system-view
[HUAWEI] vlan batch 10
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] port link-type trunk 
[HUAWEI-GigabitEthernet0/0/1] port trunk allow-pass vlan 10
[HUAWEI-GigabitEthernet0/0/1] quit
[HUAWEI] dhcp enable
[HUAWEI] dhcp snooping enable
[HUAWEI] vlan 10
[HUAWEI-vlan10] dhcp snooping enable
[HUAWEI-vlan10] dhcp snooping trusted interface gigabitethernet 0/0/1
[HUAWEI-vlan10] ip source check user-bind enable

More Information: S Series Switches Common Operation Guide