Dhcp Snooping Support For Option 82 - HP 4800G Series Configuration Manual

Figure 5-2 Configure trusted ports in a cascaded network
DHCP client
Host A
DHCP snooping
GE1/0/1
GE1/0/3
DHCP client
Host B
GE1/0/1
GE1/0/4
DHCP client GE1/0/3
Host C
DHCP client
Host D
Table 5-1 describes roles of the ports shown in
Table 5-1 Roles of ports
Device
Switch A GE1/0/1
Switch B GE1/0/3 and GE1/0/4
Switch C GE1/0/1

DHCP Snooping Support for Option 82

Option 82 records the location information of the DHCP client. The administrator can locate the DHCP
client to further implement security control and accounting. For more information, refer to
option (Option 82).
If DHCP snooping supports Option 82, it will handle a client's request according to the contents defined
in Option 82, if any. The handling strategies are described in the table below.
If a reply returned by the DHCP server contains Option 82, the DHCP snooping device will remove the
Option 82 before forwarding the reply to the client. If the reply contains no Option 82, the DHCP
snooping device forwards it directly.
Switch A
GE1/0/1
GE1/0/2 GE1/0/4
GE1/0/3
GE1/0/2
DHCP snooping
Switch B
Untrusted port
DHCP server
GE1/0/2 Eth1/1
DHCP snooping
Switch C
Untrusted ports
Trusted ports disabled from recording binding entries
Trusted ports enabled to record binding entries
Figure 5-2.
Trusted port disabled from
recording binding entries
GE1/0/3
GE1/0/1
GE1/0/3 and Ethernet 1/4
5-3
Trusted port enabled to
record binding entries
GE1/0/2
GE1/0/2
GE1/0/2
Relay agent