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1.
Create and maintain binding table for ARP Inspection function.
2.
Filter the DHCP server’s packets that the DHCP server connects to an un-trusted
port.
The DHCP server connected to an untrusted port will be filtered.
Notices
There are a global state and per VLAN states.
When the global state is disabled, the DHCP Snooping on the Switch is disabled even
per VLAN states are enabled.
When the global state is enabled, user must enable per VLAN states to enable the
DHCP Snooping on the specific VLAN.
VLAN 1
: port 1-4.
DHCP Client-1
: connect to port 3.
DHCP Server
: connect to port 1.
Procedures:
1.
Default environments:
A.
DHCP Client-1: ipconfig /release
B.
DHCP Client-1: ipconfig /renew
DHCP Client-1 can get an IP address.
2.
Enable the global DHCP Snooping.
A.
L2SWITCH(config)#dhcp-snooping
B.
DHCP Client-1: ipconfig /release
C.
DHCP Client-1: ipconfig /renew
DHCP Client-1 can get an IP address.
3.
Enable the global DHCP Snooping and VLAN 1 DHCP Snooping.
A.
L2SWITCH(config)#dhcp-snooping
B.
L2SWITCH(config)#dhcp-snooping vlan 1
C.
DHCP Client-1: ipconfig /release
D.
DHCP Client-1: ipconfig /renew
DHCP Client-1 cannot get an IP address.
; Because the DHCP server connects to a un-trust port.
4.
Enable the global DHCP Snooping and VLAN 1 DHCP Snooping.