D-Link DGS-1250 Emulator - Page 108
ip dhcp relay information check
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DGS-1250 Series Gigabit Ethernet Smart Managed Switch CLI Reference Guide request packet is a relayed packet, the Gateway IP Address (GIADDR) of the packet is the source of the request. If the GIADDR is zero, the subnet of the received interface is the source of the packet. In a DHCP relay pool, the user can further use the class command and the relay target command to define the relay target address for the request packets that match the option pattern. Example This example shows how to create a DHCP relay pool, called pool1. In the relay pool, the subnet 172.19.18.0/255.255.255.0 is specified as the source subnet. 10.2.1.1 is specified as the relay destination address. Switch# configure terminal Switch(config)# ip dhcp pool pool1 switch(config-dhcp-pool)# relay source 172.19.18.0 255.255.255.0 switch(config-dhcp-pool)# relay destination 10.2.1.1 switch(config-dhcp-pool)# 15-4 ip dhcp relay information check This command is used to enable the DHCP relay agent to validate and remove the relay agent information option in the received DHCP reply packet. Use the no form of this command to globally disable the check for Option 82. ip dhcp relay information check no ip dhcp relay information check Parameters None. Default By default, this option is disabled. Command Mode Global Configuration Mode. Usage Guideline This command takes effect when the service dhcp command is enabled. The ip dhcp relay information check command and the ip dhcp relay information check-reply command together determine whether the check function of Option 82 is effective for an interface. If the ip dhcp relay information check-reply command is not configured for an interface, the global setting takes effect. If the ip dhcp relay information check-reply command is configured for an interface, the interface setting takes effect. When the check for Option 82 of the reply packet is enabled, the device will check the validity of the Option 82 field in DHCP reply packets it receives from the DHCP server. If the Option 82 field in the received packet is not present or the option is not the original option inserted by the agent (by checking the remote ID sub-option, the relay agent drops the packet. Otherwise, the relay agent removes the Option 82 field and forwards the packet. If the check is disabled, the packet will be directly forwarded. Example This example shows how to enable the global DHCP relay agent check. Switch#configure terminal Switch(config)# ip dhcp relay information check switch(config)# 105
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