H3C Technologies H3C S7500E Series Switches - Manual (Page 42)

4-7
Figure 4-8 Sub-option 1 in normal padding format
z 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. The following figure gives
its format. The value of the sub-option type is 2, and that of the remote ID type is 0.
Figure 4-9 Sub-option 2 in normal padding format
2) Verbose padding format
The padding contents for sub-options in the verbose padding format are as follows:
z Sub-option 1: Padded with the user-specified access node identifier (ID of the device that adds
Option 82 in DHCP messages), and the type, number, and VLAN ID of the interface that received
the client’s request. Its format is shown in Figure 4-10 .
Figure 4-10 Sub-option 1 in verbose padding format
In Figure 4-10 , except that the VLAN ID field has a fixed length of 2 bytes, all the other padding
contents of sub-option 1 are length variable.
z 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
that in normal padding format, as shown in Figure 4-9 .
Option 184
Option 184 is a reserved option, and parameters in the option can be defined as needed. The device
supports Option 184 carrying the voice related parameters, so a DHCP client with voice functions can
get an IP address along with specified voice parameters from the DHCP server.
Option 184 involves the following sub-options: