H3C S9500 Series Operation Manual page 58

Operation Manual – DHCP
H3C S9500 Series Routing Switches
sub-option 1: Padded with the user-specified access node identifier, and the type,
number, PVC identifier (used when the interface type is ATM), and VLAN ID of the
interface that received the client's request. Its format is shown in the following
figure.
Figure 3-5 Sub-option 1 in verbose padding format
Note:
In the above figure, except that the VLAN ID field has a fixed length of 2 bytes, all the
other fields of sub-option 1 are length variable.
sub-option 2: Padded with the MAC address of the DHCP relay agent interface or the
MAC address of the DHCP snooping device that received the client's request. It has the
same format as normal padding format, as shown in
II. Handling strategies for Option 82 on the relay agent
If the DHCP relay agent 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 relay agent will
remove Option 82 before forwarding the reply to the client.
If a client's
request message
has...
Option 82
Handling
Padding format
strategy
Drop —
Keep —
Normal
Replace
Verbose
3-9
Chapter 3 DHCP Relay Agent Configuration
Figure 3-4.
The DHCP relay agent
Drop the message.
Forward the message
without changing Option 82.
Forward the message after
replacing the original Option
82 with the Option 82
padded in normal format.
Forward the message after
replacing the original Option
82 with the Option 82
padded in verbose format.
will...