测试目的
路由器接口通过DHCP协议动态获取IP地址
应用场景
模拟自动化网管配置，上联设备作为DHCP中继，配置中继信息，当下联设备插入上联设备下联口，下联设备开启DHCP地址分配，则下联设备上联口即可获得IP地址。从而实现下联设备的上线实现统一管理。
测试环境
eNSP 1.3.00.100 V100R003C000SPC100window 10
测试拓扑
拓扑配置
DHCP服务器配置
修改路由器名称。开启全局DHCP功能。配置端口地址，开启端口DHCP分配使能。构建IP地址池。配置静态路由。
sys
Enter system view, return user view with Ctrl+Z.
[Huawei]sysname DHCP-Server
[DHCP-Server]
[DHCP-Server]dhcp enable
[DHCP-Server]
[DHCP-Server]interface GigabitEthernet 0/0/0
[DHCP-Server]ip address 192.168.100.1 255.255.255.0
[DHCP-Server]dhcp select global
[DHCP-Server]q
[DHCP-Server]
[DHCP-Server]ip pool pool-10
[DHCP-Server-ip-pool-pool-10]network 192.168.10.0 mask 255.255.255.252
[DHCP-Server-ip-pool-pool-10]gateway-list 192.168.10.1
[DHCP-Server-ip-pool-pool-10]q
[DHCP-Server]
[DHCP-Server]ip route-static 192.168.0.0 16 192.168.100.2
[DHCP-Server]q
save
The current configuration will be written to the device.
Are you sure to continue? (y/n)[n]:y
It will take several minutes to save configuration file, please wait.......
Configuration file had been saved successfully
Note: The configuration file will take effect after being activated
云图配置
云图没有亦可以，只是体现DHCP服务器可能在不同的网络。开启两个UDP端口即可。 
上联设备（DHCP中继）配置
修改名称开启全局DHCP功能。配置GE0/0/1和DHCP服务器互联。配置GE0/0/0端口地址，DHCP中继，DHCP服务器地址。
sys
Enter system view, return user view with Ctrl+Z.
[Huawei]sysname DHCP-Relay
[DHCP-Relay]dhcp enable
[DHCP-Relay]
[DHCP-Relay]interface GigabitEthernet 0/0/1
[DHCP-Relay-GigabitEthernet0/0/1]ip address 192.168.100.2 255.255.255.0
[DHCP-Relay-GigabitEthernet0/0/1]q
[DHCP-Relay]
[DHCP-Relay]interface GigabitEthernet 0/0/0
[DHCP-Relay-GigabitEthernet0/0/0]ip address 192.168.10.1 255.255.255.252
[DHCP-Relay-GigabitEthernet0/0/0]dhcp select relay
[DHCP-Relay-GigabitEthernet0/0/0]dhcp relay server-ip 192.168.100.1
[DHCP-Relay-GigabitEthernet0/0/0]q
[DHCP-Relay]q
save
The current configuration will be written to the device.
Are you sure to continue? (y/n)[n]:y
It will take several minutes to save configuration file, please wait.......
Configuration file had been saved successfully
Note: The configuration file will take effect after being activated
下联设备（DHCP客户端）配置
修改名称开启全局DHCP功能。开启GE0/0/0的DHCP地址分配开启默认路由
sys
Enter system view, return user view with Ctrl+Z.
[Huawei]sysname DHCP-Client
[DHCP-Client]
[DHCP-Client]dhcp enable
[DHCP-Client]
[DHCP-Client]interface GigabitEthernet 0/0/0
[DHCP-Client-GigabitEthernet0/0/0]ip address dhcp-alloc
[DHCP-Client-GigabitEthernet0/0/0]q
[DHCP-Client]q
save
The current configuration will be written to the device.
Are you sure to continue? (y/n)[n]:y
It will take several minutes to save configuration file, please wait.......
Configuration file had been saved successfully
Note: The configuration file will take effect after being activated
抓包报文
通过抓包报文发现实际交互是由中继与服务器进行的，这个也是中继的职责哈。 
拓扑说明
实际应用中一般不会直接一起配置DHCP服务器地址池和DHCP 中继。而是先配置DHCP中继，再等DHCP客户端接入中继开启DHCP功能发送DHCP discover报文给DHCP服务器，DHCP服务器根据discover报文中Relay地址（一般作为DHCP客户端的网关），厂商信息构建地址池。整个流程并非完全自动化，需要人工在合适的时机去触发，这个主要便于可管可控，但是总体上人为的配置基本可以忽略，从而实现运维自动化。
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