H3C Technologies H3C S10500 Series Switches - Manual (Page 83)

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Table 4 describes the roles of the ports shown in Figure 34 .
Table 4 Roles of ports
Device Untrusted port
Trusted port disabled from
recording binding entries
Trusted port enabled to
record binding entries
Switch A GigabitEthernet 1/0/1 GigabitEthernet 1/0/3 GigabitEthernet 1/0/2
Switch B
GigabitEthernet 1/0/3 and
GigabitEthernet 1/0/4
GigabitEthernet 1/0/1 GigabitEthernet 1/0/2
Switch C GigabitEthernet 1/0/1
GigabitEthernet 1/0/3 and
GigabitEthernet 1/0/4
GigabitEthernet 1/0/2
DHCP snooping support for Option 82
Option 82 records the location information of the DHCP client so the administrator can locate the DHCP
client for security control and accounting purposes. For more information, see the chapter “DHCP relay
agent configuration.”
If DHCP snooping supports Option 82, it handles a client’s request according to the contents defined in
Option 82, if any. The handling strategies are described in Table 5 .
If a reply returned by the DHCP server contains Option 82, the DHCP snooping device removes the
Option 82 before forwarding the reply to the client. If the reply contains no Option 82, the DHCP
snooping device forwards it directly.
Table 5 Handling strategies of DHCP snooping
If a client’s
requesting message
has…
Handling
strategy
Padding format The DHCP snooping device will…
Drop — Drop the message.
Keep Random
Forward the message without changing Option
82.
normal
Forward the message after replacing the
original Option 82 with the Option 82 padded
in normal format.
verbose
Forward the message after replacing the
original Option 82 with the Option 82 padded
in verbose format.
Option 82
Replace
user-defined
Forward the message after replacing the
original Option 82 with the user-defined
Option 82.
— normal
Forward the message after adding the Option
82 padded in normal format.
— verbose
Forward the message after adding the Option
82 padded in verbose format.
no Option 82
— user-defined
Forward the message after adding the
user-defined Option 82.