MSR36-20_1设备作为DHCP服务器，S5820V2-54QS-GE_2上分别创建vlan10和vlan20，连接PC_3和PC_4，交换机连接路由器的接口属于vlan100，配置IP地址10.1.1.2/24，通过DHCP服务器给vlan10和vlan20的PC机分配IP地址。
DHCP服务器的配置：
[DHCP server]dhcp enable
[DHCP server]dhcp server ip-pool 1
[DHCP server-dhcp-pool-1]network 192.168.1.0 24//给vlan10的PC机分配的IP地址
[DHCP server-dhcp-pool-1]gateway-list 192.168.1.1//让PC机获取IP地址的同时也获取到网关的信息
[DHCP server]dhcp server ip-pool 2
[DHCP server-dhcp-pool-2]network 192.168.2.0 24
[DHCP server-dhcp-pool-2]gateway-list 192.168.2.1
[DHCP server]dhcp server forbidden-ip 192.168.1.1//192.168.1.1的地址已经给了网关，不允许再把这个地址分配给PC机
[DHCP server]dhcp server forbidden-ip 192.168.2.1
[DHCP server]ip route-static 192.168.1.0 24 10.1.1.2//DHCP server上配置到达PC所在网段的静态路由，经常有同学这一步的命令忘记敲了。
[DHCP server]ip route-static 192.168.2.0 24 10.1.1.2
DHCP中继设备的配置：
[SW]dhcp enable
[SW]interface Vlan-interface 10
[SW-Vlan-interface10]dhcp select relay//给vlan10的三层虚接口设置中继功能
[SW-Vlan-interface10]dhcp relay server-address 10.1.1.1//因为中继的功能可以把广播变成单播的报文，需要在中继接口指定DHCP服务器的IP地址信息
[SW]interface Vlan-interface 20
[SW-Vlan-interface20]dhcp select relay
[SW-Vlan-interface20]dhcp relay server-address 10.1.1.1
