DHCP配置
dhcp request ：由用户发向服务器的广播报文，目的是用来通知其他服务器是否使用服务器分配的ip地址。同时该报文还有续租的作用。
dhcp 租期： 目的是合理有效的使用ip地址。分配给客户端的ip地址都是有租期的，当到达租期一半的时候，客户端会自动触发续租消息（dhcp request报文）。
DHCP协议报文：
DHCPDISCOVER: 由客户端广播来查找可用的服务器
DHCP OFFER: 服务器用来响应客户端的DHCP DISCOVER报文，并指定相应的配置参数。
DHCP REQUEST: 由客户端发送给服务器来请求配置参数或者请求配置确认或者续借租期。
DHCP ACK: 由服务器到客户端，含有配置参数包括IP地址。
DHCP高级报文：
DHCP DECLINE： 当客户端发现地址已经被使用时，用来通知服务器。
DHCP INFORM： 客户端已经有IP地址时用它来向服务器请求其他的配置参数。
DHCP NAK： 由服务器发送给客户端来表明客户端的地址请求不正确或者租期已过期。
DHCP RELEASE： 客户端要释放地址时用来通知服务器。
DHCP配置
全局建立地址池
[Huawei]ip pool xiaoguo
[Huawei-ip-pool-xiaoguo]gateway-list 192.168.1.1
[Huawei-ip-pool-xiaoguo]network 192.168.1.0 mask 24
[Huawei-ip-pool-xiaoguo]dns-list 8.8.8.8
[Huawei]interface GigabitEthernet 0/0/0
[Huawei-GigabitEthernet0/0/0]dhcp select global
修改租期(可选)
[Huawei]ip pool xiaoguo
[Huawei-ip-pool-xiaoguo]lease day 0 hour 20
绑定固定mac对应IP(可选)
[Huawei]ip pool xiaoguo
[Huawei-ip-pool-xiaoguo]static-bind ip-address 192.168.1.254 mac-address 5489-98E4-199F
排除地址段(可选)
[Huawei]ip pool xiaoguo
[Huawei-ip-pool-xiaoguo]excluded-ip-address 192.168.1.200 192.168.1.250
调试指令：显示已经分配的ip地址的使用情况
[Huawei]display ip pool name xiaoguo used
重置分配记录
2.基于接口的dhcp(简单、便捷)
[Huawei]interface GigabitEthernet 0/0/0
[Huawei-GigabitEthernet0/0/0]ip address 192.168.1.1 24
[Huawei-GigabitEthernet0/0/0]dhcp select interface
[Huawei-GigabitEthernet0/0/0]dhcp server dns-list 8.8.8.8
3.dhcp relay(dhcp中继)
sw1:
[Huawei]sysname sw1
[sw1]undo info-center enable
[sw1]vlan batch 10 20 800
[sw1]dhcp enable
[sw1]interface Vlanif 800
[sw1-Vlanif800]ip add 192.168.254.1 24
[sw1]interface Vlanif 10
[sw1-Vlanif10]ip add 192.168.10.1 24
[sw1-Vlanif10]dhcp select relay
[sw1-Vlanif10]dhcp relay server-ip 192.168.254.2
[sw1]interface Vlanif 20
[sw1-Vlanif20]ip add 192.168.20.1 24
[sw1-Vlanif20]dhcp select relay
[sw1-Vlanif20]dhcp relay server-ip 192.168.254.2
[sw1]interface GigabitEthernet 0/0/1
[sw1-GigabitEthernet0/0/1]port link-type access
[sw1-GigabitEthernet0/0/1]port default vlan 800
[sw1-GigabitEthernet0/0/1]int g0/0/2
[sw1-GigabitEthernet0/0/2]port link-type trunk
[sw1-GigabitEthernet0/0/2]port trunk allow-pass vlan 10
[sw1-GigabitEthernet0/0/2]int g0/0/3
[sw1-GigabitEthernet0/0/3]port link-type trunk
[sw1-GigabitEthernet0/0/3]port trunk allow-pass vlan 20
sw2:
[Huawei]sysname sw2
[sw2]vlan 10
[sw2]interface e0/0/1
[sw2-Ethernet0/0/1]port link-type trunk
[sw2-Ethernet0/0/1]port trunk allow-pass vlan 10
[sw2-Ethernet0/0/1]int e0/0/2
[sw2-Ethernet0/0/2]port default vlan 10
sw3:
[Huawei]sysname sw3
[sw3]vlan 20
[sw3]int e0/0/1
[sw3-Ethernet0/0/1]port link-type trunk
[sw3-Ethernet0/0/1]port trunk allow-pass vlan 20
[sw3-Ethernet0/0/1]int e0/0/2
[sw3-Ethernet0/0/2]port link-type access
[sw3-Ethernet0/0/2]port default vlan 20
R1:
[Huawei]sysname R1-DHCP
[R1-DHCP]int g0/0/0
[R1-DHCP-GigabitEthernet0/0/0]dhcp select global
[R1-DHCP-GigabitEthernet0/0/0]ip add 192.168.254.2 24
[R1-DHCP]ip route-static 0.0.0.0 0 192.168.254.1
[R1-DHCP]ip pool vlan10
[R1-DHCP-ip-pool-vlan10]network 192.168.10.0 mask 24
[R1-DHCP-ip-pool-vlan10]gateway-list 192.168.10.1
[R1-DHCP-ip-pool-vlan10]dns-list 8.8.8.8
[R1-DHCP]ip pool vlan20
[R1-DHCP-ip-pool-vlan20]network 192.168.20.0 mask 24
[R1-DHCP-ip-pool-vlan20]gateway-list 192.168.20.1
[R1-DHCP-ip-pool-vlan20]dns-list 8.8.8.8