Dhcp Snooping Support For Option - H3C S7500E Series Operation Manual

Operation Manual – DHCP
H3C S7500E Series Ethernet Switches
ports, GE2/0/3 on Switch A, GE2/0/1 on Switch B, GE2/0/3 and GE2/0/4 on Switch C,
which are not directly connected to DHCP clients, from recording client's IP-to-MAC
bindings.
DHCP client
Host A
DHCP client
Host B
DHCP client
Host C
DHCP client
Host D
Figure 5-2 Configure trusted ports in a cascaded network

5.1.3 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
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, it forwards it directly.
DHCP snooping
Switch A
GE2/0/1 GE2/0/2 GE2/0/4
GE2/0/3
GE2/0/1
GE2/0/4 GE2/0/2
DHCP snooping
GE2/0/3
Switch B
Relay agent option (Option
Chapter 5 DHCP Snooping Configuration
GE2/0/1
GE2/0/2 GE2/0/1
DHCP snooping
GE2/0/3
Switch C
82).
5-3
DHCP server