Operation Manual – DHCPH3C S7500 Series Ethernet Switches Chapter 3 DHCP Relay Agent Configuration3-5To enhance reliability, you can set multiple DHCP servers on the same network.These DHCP servers form a DHCP server group. When the interface establishesmapping relationship with the DHCP server group, the interface forwards the DHCPpackets to all servers in the server group.Follow these steps to configure an interface to operate in DHCP relay agent mode:To do… Use the command… RemarksEnter system view system-view —Configure the DHCPserver IP address(es) in aspecified DHCP servergroupdhcp-server groupNo ipip-address&<1-8>RequiredBy default, no DHCPserver IP address isconfigured in a DHCPserver groupinterface interface-typeinterface-numberMap an interface to aDHCP server groupdhcp-server groupNoRequiredBy default, a VLANinterface is not mapped toany DHCP server groupNote:z You can configure up to eight external DHCP IP addresses in a DHCP servergroup.z You can map multiple VLAN interfaces to one DHCP server group. But one VLANinterface can be mapped to only one DHCP server group. If you execute thedhcp-server groupNo command repeatedly, the new configuration overwrites theprevious one.z You need to configure the group number specified in the dhcp-server groupNocommand in VLAN interface view by using the command dhcp-server groupNo ipipaddress-address&<1-8> in advance.3.2.4 Configuring DHCP Relay Agent SecurityI. Configuring address checkingWhen a DHCP client obtains an IP address from a DHCP server with the help of aDHCP relay agent, the DHCP relay agent creates an entry (dynamic entry) in the useraddress table to track the IP-MAC address binding information about the DHCP client.You can also configure user address entries manually (static entries) to bind an IPaddress and a MAC address statically.The purpose of the address checking function on DHCP relay agent is to preventunauthorized users from statically configuring IP addresses to access externalnetworks. With this function enabled, a DHCP relay agent inhibits a user from
