D-Link DES-3828 Product Manual - Page 320

xStack DES-3800 Series Layer 3 Stackable Fast Ethernet Managed Switch CLI Manual config dhcp_relay option_82 state Purpose Syntax Description Parameters Restrictions Used to configure the state of DHCP relay agent information option 82 of the switch. config dhcp_relay option_82 state [enable | disable] This command is used to configure the state of DHCP relay agent information option 82 of the switch. The relay agent will insert and remove DHCP relay information (option 82 field) in messages between DHCP server and client. When the relay agent receives the DHCP request, it adds the option 82 information, and the IP address of the relay agent (if the relay agent is configured), to the packet. Once the option 82 information has been added to the packet it is sent on to the DHCP server, which receives the packet, and if the server is capable of option 82, it can implement policies like restricting the number of IP addresses that can be assigned to a single remote ID or circuit ID. The DHCP server will then echo the option 82 field in the DHCP reply. The DHCP server unicasts the reply to the back to the relay agent if the request was relayed to the server by the relay agent. The Switch then verifies that it originally inserted the option 82 data. Finally, the relay agent removes the option 82 field and forwards the packet to the switch port that is connected to the DHCP client that sent the DHCP request. enable - Choose this parameter to enable the addition of option 82 information to a packet. disable- Choose disable the relay agent from inserting and removing DHCP relay information (option 82 field) in messages between DHCP servers and clients, and the check and policy settings will have no effect. Only Administrator or Operator-level users can issue this command. Example usage: To configure DHCP relay option 82 state: DES-3800:admin#config dhcp_relay option_82 state enable Command: config dhcp_relay option_82 state enable Success. DES-3800:admin# config dhcp_relay option_82 check Purpose Syntax Description Parameters Used to configure the checking mechanism of DHCP relay agent information option 82 of the switch. config dhcp_relay option_82 check [enable | disable] This command is used to configure the checking mechanism of DHCP/BOOTP relay agent information option 82 of the switch. The relay agent will check the validity of the packet's option 82 field. If the switch receives a packet that contains the option 82 field from a DHCP client, the switch drops the packet because it is invalid. In packets received from DHCP servers, the relay agent will drop invalid messages. enable - Choose this parameter to enable validity checking of option 82 within packets. 316