使用路由器，为校园网内多个VLAN内电脑设备，自动分配IP地址
使用路由器作DHCP服务器
一个大中型校园网络中，有一台路由器，1000台终端设备，用户的计算机通过以太网交换机连接到路由器上，通过路由器访问其他网络，这些设备手动分配IP地址工作很繁琐，可以通路由器给PC设备自动分配IP地址。
下面演示使用DHCP中继来给电脑终端自动分配IP地址的配置方法，DHCP中继是用于在DHCP服务器与电脑终端之间转发DHCP报文，主要用于DHCP服务器与电脑终端不在同一个网段时。
路由器R1配置
1-启用DHCP服务
[R1]dhcp enable
2-端口配置(配置IP，作为管理IP地址)
[R1]interface GigabitEthernet 0/0/0
[R1-GigabitEthernet0/0/0]ip address 192.168.99.1 24
[R1-GigabitEthernet0/0/0]q
3-建立地址池，有几个VLAN创建几个地址池：
[R1]ip pool vlan10
[R1-ip-pool-vlan10]network 192.168.10.0 mask 255.255.255.0；配置网段
[R1-ip-pool-vlan10]gateway-list 192.168.10.254；PC网关
[R1-ip-pool-vlan10]dns-list 8.8.8.8 114.114.114.114；DNS服务器
[R1]ip pool vlan20
[R1-ip-pool-vlan20]gateway-list 192.168.20.254
[R1-ip-pool-vlan20]network 192.168.20.0 mask 255.255.255.0
[R1-ip-pool-vlan20]dhcp server lease day 3
[R1-ip-pool-vlan20]dns-list 8.8.8.8
[R1-ip-pool-vlan20]q
[R1]
4-在网关所在接口，开启DHCP功能
[R1]interface GigabitEthernet 0/0/0
[R1-GigabitEthernet0/0/0]dhcp select global //全局地址池配置
5-配置路由
[R1]ip route-static 192.168.10.0 24 192.168.99.2
[R1]ip route-static 192.168.20.0 24 192.168.99.2
[R1]
交换机SW1配置
[Huawei]sysname SW1
[SW1]undo info-center enable
[SW1]vlan batch 10 20
1-配置交换机管理IP
[SW1]interface Vlanif 1
[SW1-Vlanif1]ip address 192.168.99.2 24
[SW1-Vlanif1]q
2-启用DHCP
[SW1]dhcp enable
3-配置VLAN
[SW1]int Vlanif 10
[SW1-Vlanif10]ip address 192.168.10.254 24
[SW1-Vlanif10]dhcp select relay //配置DHCP中继
[SW1-Vlanif10]dhcp relay server-ip 192.168.99.1
[SW1-Vlanif10]q
[SW1]
[SW1]int vlan20
[SW1-Vlanif20]ip address 192.168.20.254 24
[SW1-Vlanif20]dhcp select relay
[SW1-Vlanif20]dhcp relay server-ip 192.168.99.1
[SW1-Vlanif20]q
[SW1]
4-配置相应的接口类型
[SW1]interface GigabitEthernet 0/0/1
[SW1-GigabitEthernet0/0/1]port link-type trunk
[SW1-GigabitEthernet0/0/1]port trunk allow-pass vlan 10 20
[SW1-GigabitEthernet0/0/1]q
[SW1]
[SW1]interface GigabitEthernet 0/0/2
[SW1-GigabitEthernet0/0/2]port link-type trunk
[SW1-GigabitEthernet0/0/2]port trunk allow-pass vlan 20
[SW1-GigabitEthernet0/0/2]q
[SW1]
交换机SW3配置
[Huawei]undo info-center enable
[Huawei]sysname SW3
[SW3]dhcp enable
[SW3]vlan batch 10 20
[SW3]interface Vlanif 1
[SW3-Vlanif1]ip address 192.168.99.3 24
[SW3-Vlanif1]q
[SW3]interface GigabitEthernet 0/0/2
[SW3-GigabitEthernet0/0/2]port link-type trunk
[SW3-GigabitEthernet0/0/2]port trunk allow-pass vlan 20
[SW3-GigabitEthernet0/0/2]q
[SW3]interface GigabitEthernet 0/0/10
[SW3-GigabitEthernet0/0/10]port link-type access
[SW3-GigabitEthernet0/0/10]port default vlan 20
[SW3-GigabitEthernet0/0/10]q
[SW3]interface GigabitEthernet 0/0/14
[SW3-GigabitEthernet0/0/14]port link-type access
[SW3-GigabitEthernet0/0/14]port default vlan 20
[SW3-GigabitEthernet0/0/14]q
[SW3]
[SW3]
交换机SW2配置
[Huawei]undo info-center enable
[Huawei]sysname SW2
[SW2]vlan 10
[SW2]interface GigabitEthernet 0/0/12
[SW2-GigabitEthernet0/0/12]port link-type access
[SW2-GigabitEthernet0/0/12]port default vlan 10
[SW2-GigabitEthernet0/0/12]q
[SW2]
[SW2]interface GigabitEthernet 0/0/1
[SW2-GigabitEthernet0/0/1]port link-type trunk
[SW2-GigabitEthernet0/0/1]port trunk allow-pass vlan 10 20
[SW2-GigabitEthernet0/0/1]q
[SW2]
5-测试
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