DHCP Option 82
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Chapter 17. DHCP Option 82
17.1 Introduction to option 82 supporting
Option: A length-variable field in DHCP packets, carrying information such as part of the
lease information and packet type. It includes at least one option and at most 255 options.
Option 82: Also known as relay agent information option. This option is a part of the Option
field in DHCP packet. According to RFC3046, option 82 lies before option 255 and after the
other options. Option 82 includes at least one sub-option and at most 255 sub-options.
Currently, the commonly used sub-options in option 82 are sub-option 1 and sub-option 2.
Sub-option 1: A sub-option of option 82. Sub-option 1 represents the agent circuit ID,
namely Circuit ID. It holds the port number and VLAN-ID of the switch port connected to the
DHCP client, and is usually configured on the DHCP relay. Generally, sub-option 1 and
sub-option 2 must be used together to identify information about a DHCP source.
Sub-option 2: A sub-option of option 82. Sub-option 2 represents the remote agent ID,
namely Remote ID. It holds the MAC address of the DHCP relay, and is usually configured on
the DHCP relay. Generally, sub-option 1 and sub-option 2 must be used together to identify
information about a DHCP source.
17.2 DHCP Option82 Configuration
17.2.1 Enable DHCP Option82
To enable option 82, you need to perform the corresponding configuration on the DHCP
server and the DHCP relay.
If the packet contains option 82, the DHCP relay processes the packet depending on the
configured policy
：
Drop: Specifies to discard the DHCP request packets that carry option 82.
Keep: Specifies to remain the DHCP request packets that carry option 82 unchanged.
Replace: Specifies to replace the option 82 carried by a DHCP request packet with that of
the DHCP relay.
Summary of Contents for S6424-S2C2 series
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