Dhcp Snooping Option 82 Application Examples - Planet WGSW-52040 Configuration Manual

Command
Port mode
ip dhcp snooping trust
no ip dhcp snooping trust

37.3 DHCP Snooping Option 82 Application Examples

DHCP Client PC1
Figure 37-1: DHCP option 82 typical application example
In the above example, layer 2 Switch1 will transmit the request message from DHCP client to
DHCP serer through enable DHCP Snooping. It will also transmit the reply message from the
server to DHCP client to finish the DHCP protocol procedure. After the DHCP SNOOPING
option 82 function is enabled, the Switch1 appends the port information of accessing Switch1
to the request message from the client by option 82.
The following is the configuration of Switch1(MAC address is 00-30-4f-02-33-01):
Switch1(config)#ip dhcp snooping enable
Switch1(config)#ip dhcp snooping binding enable
Switch1(config)# ip dhcp snooping information enable
Switch1(Config-If-Ethernet1/12)#ip dhcp snooping trust
Linux ISC DHCP Server supports option 82, its configuration file /etc/dhcpd.conf is
ddns-update-style interim;
ignore client-updates;
class "Switch1Vlan1Class1" {
match if option
Switch1
Vlan1:eth1/3
agent.circuit-id
37-86
Explanation
Set or delete DHCP SNOOPING trust
attribute of ports.
DHCP Server
= "Vlan1+Ethernet1/3" and option