Dell N3200-ON EMC Networking N-Series Switches CLI Reference Guide version 6.7 - Page 1516

ip dhcp relay information option server-override Use the ip dhcp relay information option server-override command to enable sending sub-option 5 (link-election) and sub-option 11 (server override) in option 82. Syntax ip dhcp relay information option server-override no ip dhcp relay information option server-override Default Configuration Sending of sub-option 5 (link-selection) and sub-option 11 (server-override) is not enabled globally, nor or any interface. Command Mode Global Configuration mode, Interface Configuration mode User Guidelines Configuring ip dhcp relay information option server-override enables the insertion of sub-option 5 and sub-option 11 in relayed DHCPDISCOVER messages. The server override and link-selection sub-options contain the incoming interface IP address of the DCHPREQUEST. The relay agent sets the gateway IP address (giaddr) to an IP address reachable by the DHCP server (outgoing interface IP address or the address configured by the ip dhcp relay source-interface command) and sets the Server Identifier Override suboption to an IPv4 address reachable by the DHCP host that sent the DHCPDISCOVER. The DHCP server uses the link selection sub-option to locate the address pool for the DHCP client and sets the server identifier option in the DHCPOFFER to the value of the Server Identifier Override sub-option received from the switch relay agent. The DHCP server sends the response to the IP address received in the giaddr option. This causes the DHCP client to use the Server Identifier Override IP address when unicasting DHCPRENEW messages and support behavior similar to DHCPv6 relay. Layer 3 Routing Commands 1516