环境：AR3为PC1的网关，AR4为DHCP服务器，与客户端地址不在同一个网段。

AR3的配置：

sysname AR3
#
dhcp enable
#
interface GigabitEthernet0/0/0
 ip address 192.168.10.254 255.255.255.0 
 dhcp select relay
 dhcp relay server-ip 192.168.100.2
#
interface GigabitEthernet0/0/1
 ip address 192.168.100.1 255.255.255.252 

AR4的配置：

sysname AR4
#
dhcp enable
#
ip pool x
 gateway-list 192.168.10.254 
 network 192.168.10.0 mask 255.255.255.0 
 dns-list 114.114.114.114 
#
interface GigabitEthernet0/0/0
 ip address 192.168.100.2 255.255.255.252 
 dhcp select global
#
ip route-static 192.168.10.0 255.255.255.0 192.168.100.1
#

DHCP中继的报文是通过单播发送的，服务器是通过路由器的端口