D-Link DGS-1210-28 Reference Manual

Also see for Web Smart Switch DGS-1210-28: Reference guide Manual Reference guide Reference guide Reference guide

Contents

4 Configuration D-Link Web Smart Switch User Manual2255DHCP Relay Agent Information Option 82 State: This field can be toggled between Enabled and Disabledusing the pull-down menu. It is used to enable or disable the DHCP Agent Information Option 82 on theSwitch. The default is Disabled.Enabled – When this field is toggled to Enabled the relay agent will insert and remove DHCP relayinformation (option 82 field) in messages between DHCP servers and clients. When the relay agentreceives 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 tothe packet it is sent on to the DHCP server. When the DHCP server receives the packet, if the serveris capable of option 82, it can implement policies like restricting the number of IP addresses that canbe assigned to a single remote ID or circuit ID. Then the DHCP server echoes the option 82 field inthe DHCP reply. The DHCP server unicasts reply to the back to the relay agent if the request wasrelayed to the server by the relay agent. The switch verifies that it originally inserted the option 82data. Finally, the relay agent removes the option 82 field and forwards the packet to the switch portthat connects to the DHCP client that sent the DHCP request.Disabled - If the field is toggled to Disabled the relay agent will not insert and remove DHCP relayinformation (option 82 field) in messages between DHCP servers and clients, and the check andpolicy settings will have no effect.DHCP Relay Agent Information Option 82 Check: This field can be toggled between Enabled andDisabled using the pull-down menu. It is used to enable or disable the Switches ability to check the validity ofthe packet’s option 82.Enabled – When the field is toggled to Enabled, the relay agent will check the validity of the packet’soption 82 fields. 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 relayagent will drop invalid messages.Disabled - When the field is toggled to Disabled, the relay agent will not check the validity of thepacket’s option 82 fields.DHCP Relay Agent Information Option 82 Policy: This field can be toggled between Replace, Drop, andKeep by using the pull-down menu. It is used to set the Switches policy for handling packets when the DHCPAgent Information Option 82 Check is set to Disabled. The default is Replace.Replace - The option 82 field will be replaced if the option 82 field already exists in the packetreceived from the DHCP client.Drop - The packet will be dropped if the option 82 field already exists in the packet received from theDHCP client.Keep -The option 82 field will be retained if the option 82 field already exists in the packet receivedfrom the DHCP client.DHCP Relay Agent Information Option 82 Remote ID: This field can be toggled between Default and UserDefine.NOTE: If the Switch receives a packet thatcontains the option-82 field from a DHCP clientand the information-checking feature is enabled,the switch drops the packet because it is invalid.However, in some instances, you might configurea client with the option-82 field. In this situation,you should disable the information-check featureso that the switch does not remove the option-82field from the packet. You can configure the actionthat the switch takes when it receives a packetwith existing option-82 information by configuringthe DHCP Agent Information Option 82 Policy.System > DHCP/BOOTP Relay > DHCP/BOOTP Relay Interface SettingsThis page allows the user to set up a server, by IP address, for relaying DHCP/BOOTP information theswitch. The user may enter a previously configured IP interface on the Switch that will be connected directlyto the DHCP/BOOTP server using the following window. Properly configured settings will be displayed in theBOOTP Relay Table at the bottom of the following window, once the user clicks the Add button under theApply heading. The user may add up to four server IPs per IP interface on the Switch. Entries may bedeleted by clicking Delete button.