FoxGate S63 series, Руководство по настройке

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DHCP option 82 Configuration
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SubOpt: the sequence number of sub-option, the sequence number of Circuit ID
sub-option is 1, the sequence number of Remote ID sub-option is 2.
Len: the number of bytes in Sub-option Value, not including the two bytes in SubOpt
segment and Len segment.
33.1.2
option 82 Working Mechanism
DHCP option 82 flow chart
If the DHCP Relay Agent supports option 82, the DHCP client should go through the
following four steps to get its IP address from the DHCP server: discover, offer, select and
acknowledge. The DHCP protocol follows the procedure below:
1
）
DHCP client sends a request broadcast message while initializing. This request
message does not have option 82.
2
）
DHCP Relay Agent will add the option 82 to the end of the request message it receives,
then relay and forward the message to the DHCP server. By default, the sub-option 1 of
option 82 (Circuit ID) is the interface information of the switch connected to the DHCP
client (VLAN name and physical port name), but the users can configure the Circuit ID as
they wish. The sub-option 2 of option 82(Remote ID) is the MAC address of the DHCP
relay device.
3
）
After receiving the DHCP request message, the DHCP server will allocate IP address
and other information for the client according to the information and preconfigured policy
DHCP Server
DHCP Client
DHCP Relay Agent
DHCP Request DHCP Request Option82
Option82 DHCP Reply
DHCP Reply