H3C S3100-52P Operation Manual page 494

Operation Manual – DHCP
H3C S3100-52P Ethernet Switch
sub-option 1 (circuit ID sub-option): Padded with the port index (smaller than the
physical port number by 1) and VLAN ID of the port that received the client's
request.
sub-option 2 (remote ID sub-option): Padded with the bridge MAC address of the
DHCP snooping device that received the client's request.
By default, when an S3100-52P Ethernet Switch serves as DHCP snooping devices,
Option 82 adopts the extended format. Refer to
extended format of the sub-options (with the default padding contents). That is, the
circuit ID or remote ID sub-option defines the type and length of a circuit ID or remote
ID.
The remote ID type field and circuit ID type field are determined by the option storage
format. They are both set to 0 in the case of HEX format and to 1 in the case of ASCII
format.
Figure 2-2 Extended format of the circuit ID sub-option
Figure 2-3 Extended format of the remote ID sub-option
In practice, some network devices do not support the type and length identifiers of the
Circuit ID and Remote ID sub-options. To interwork with these devices, an S3100-52P
Ethernet Switch supports Option 82 in the standard format. Refer to
Figure 2-5
In the standard format, the Circuit ID or Remote ID sub-option does not contain the
two-byte type and length fields of the circuit ID or remote ID.
Figure 2-4 Standard format of the circuit ID sub-option
for the standard format of the sub-options (with the default padding contents).
Chapter 2 DHCP Snooping Configuration
Figure 2-2
2-3
and Figure 2-3 for the
Figure 2-4 and