DHCP常用配置知识总结
DHCP常用配置知识总结
DHCP是很常用的一个功能，无论是家用还是企业用。但是需要提醒的是，在一网段中只能有一个DHCP服务器，不能多。换言之，只要在本网段中存在DHCP服务器，就能发挥动态分配IP地址的功能。
家用一般采用无线路由器做DHCP服务器，根据导航自动即可设置成功，有些默认模式已设置好，通电即可使用。
但在企业里，因存在内网和访客网，办公网和生产网等，有固定IP地址和动态IP地址之分。要根据实际情况进行DHCP服务的部署。
DHCP协议理论应答模型
Discover 谁有？客户端发出信号，
Offer 我有！在网络中，主动报告，
Request 客户端发出请求！给我一个
Ack 确认，好的！服务器确认并分配
构建eNSP模型，实际抓包数据
企业里比较常用的方法有：用服务器做DHCP服务器，或者通过防火墙或路由器的端口，开通本网段所在的DHCP服务。相关如下：
1.DHCP的全局模式配置
2.DHCP的接口模式配置
3.DHCP的中继代理
4.DHCP的三层交换
1.DHCP的全局模式配置（子接口的DHCP配置方式类似）
[Router] dhcp enable //启用DHCP
//针对网段192.168.10.0进行配置
[Router] ip pool test //建立DHCP地址池及租约
[Router-ip-pool-test] network 192.168.10.0 mask 24 //对应的网段
[Router-ip-pool-test] gateway-list 192.168.10.1 //对应的网关
[Router-ip-pool-test] dns-list 8.8.8.8 //对应的DNS，根据实际情况
[Router-ip-pool-test] lease day 1 hour 0 minut 0 //租约时长
[Router-ip-pool-test] excluded-ip-address 192.168.10.250 192.168.10.254 //不参与分配的地址
[Router] interface GigabitEthernet 0/0/0 //进入对应的接口
[Router-GigabitEthernet0/0/0] ip address 192.168.10.1 24 //所配的IP地址与地址池的网关相一致,就能自动匹配，这点不要搞糊了
[Router-GigabitEthernet0/0/0] dhcp select global //把本接口的DHCP配置成全局模式
//针对网段192.168.20.0进行配置
[Router] ip pool test2 //建立针对192.168.20.0网段的租约
[Router-ip-pool-test2] network 192.168.20.0 mask 24 //地址池对应的网段
[Router-ip-pool-test2] gateway-list 192.168.20.1 //对应的网关
[Router-ip-pool-test2] dns-list 8.8.8.8 .//.对应的DNS
[Router-ip-pool-test2] lease day 1 hour 0 minute 0 //租约的时长
[Router-ip-pool-test2] excluded-ip-address 192.168.20.210 192.168.20.254 //不参与分配的地址
[Router] interface GigabitEthernet0/0/1 //路由器对应的接口
[Router-GigabitEthernet0/0/1] ip address 192.168.20.1 24 //所配的IP地址与地址池的网关相一致,就能自动匹配，这点不要搞糊了
[Router-GigabitEthernet0/0/1] dhcp select global //把本接口的DHCP配置成全局模式
//两个网段获取IP地址信息，分别位于两网段获取的IP地址
PC4>ipconfig
Link local IPv6 address...........: fe80::5689:98ff:fe4f:2ce0
IPv6 address......................: :: / 128
IPv6 gateway......................: ::
IPv4 address......................: 192.168.10.248
Subnet mask.......................: 255.255.255.0
Gateway...........................: 192.168.10.1
Physical address..................: 54-89-98-4F-2C-E0
DNS server........................: 8.8.8.8
PC8>ipconfig
Link local IPv6 address...........: fe80::5689:98ff:fe9f:27c6
IPv6 address......................: :: / 128
IPv6 gateway......................: ::
IPv4 address......................: 192.168.20.209
Subnet mask.......................: 255.255.255.0
Gateway...........................: 192.168.20.1
Physical address..................: 54-89-98-9F-27-C6
DNS server........................: 8.8.8.8
2、DHCP接口模式配置命令（在防火墙或路由器的端口上配置DHCP，可以用一台防火墙或路由器设置多个网段的DHCP）
[Router]dhcp enable
[Router] interface GigabitEthernet 0/0/0
[Router-GigabitEthernet0/0/0] ip address 192.168.100.1 24
[Router] interface GigabitEthernet 0/0/0
[Router-GigabitEthernet0/0/0] dhcp select interface //dhcp
[Router-GigabitEthernet0/0/0] dhcp server dns-list 8.8.8.8
[Router-GigabitEthernet0/0/0] dhcp server lease day 1 hour 0 minute 0
[Router-GigabitEthernet0/0/0] dhcp server exclude-ip-address 192.168.100.100 192.168.100.200 //不参与分配的ip地址
//针对端口启动DHCP，并以本端口的IP地址为网关；以下为PC机查询结果
PC>ipconfig
Link local IPv6 address...........: fe80::5689:98ff:feeb:35c8
IPv6 address......................: :: / 128
IPv6 gateway......................: ::
IPv4 address......................: 192.168.100.253
Subnet mask.......................: 255.255.255.0
Gateway...........................: 192.168.100.1
Physical address..................: 54-89-98-EB-35-C8
DNS server........................: 8.8.8.8
3.HDCP中继代理模式配置 （有时候，DHCP server不在本地，DHCP相关控制机制在远处某台路由器或防火墙上，可采用这种方式）
//DHCP Server配置
[DhcpServer] interface GigabitEthernet 0/0/0
[DhcpServer-GigabitEthernet0/0/0] ip address 192.168.12.1 24 //配置路由器接口IP地址
[DhcpServer] dhcp enable //启用DHCP服务
[DhcpServer] ip pool agentTest //建立DHCP地址池及租约
[DhcpServer-ip-pool-agentTest] network 192.168.1.0 mask 24 //dhcp 所涉及网段
[DhcpServer-ip-pool-agentTest] gateway-list 192.168.1.1 //dhcp关联网关
[DhcpServer-ip-pool-agentTest] dns-list 8.8.8.8 //dhcp对应的DNS
[DhcpServer-ip-pool-agentTest] lease day 1 hour 0 minute 0 //dhcp租约时长
[DhcpServer-ip-pool-agentTest] excluded-ip-address 192.168.1.1 192.168.1.10 //不参与分配的IP地址
[DhcpServer] interface GigabitEthernet 0/0/0
[DhcpServer-GigabitEthernet0/0/0] dhcp select global //指定dhcp为全局模式
[DhcpServer] ip route-static 192.168.1.0 24 192.168.12.2 //配置相关路由
//配置DHCP代理
[DhcpAgent] dhcp enable //在DHCP代理路由器上，启用dhcp。本质上是DHCP服务之间在进行沟通并得出相应的结果。只是各设备扮演不同的角色。
[DhcpAgent] interface g0/0/0
[DhcpAgent-GigabitEthernet0/0/0] ip address 192.168.12.2 24
[DhcpAgent] interface g0/0/1
[DhcpAgent-GigabitEthernet0/0/1] ip address 192.168.1.1 24
[DhcpAgent-GigabitEthernet0/0/1] dhcp select relay //对应交换的接口，dhcp模式设为relay中继模式，这是关键步骤
[DhcpAgent-GigabitEthernet0/0/1] dhcp relay server-ip 192.168.12.1 //dhcp模式中继时，去寻找192.168.12.1，这是关键步骤，为中继指定映射点。中间可能隔了多个路由器，这和dhcp配置无关，只要路由能到。
PC>ipconfig /renew
IP Configuration
Link local IPv6 address...........: fe80::5689:98ff:fec8:2bc3
IPv6 address......................: :: / 128
IPv6 gateway......................: ::
IPv4 address......................: 192.168.1.254 //这个地址是接口192.168.12.1所在的dhcp服务器分配的
Subnet mask.......................: 255.255.255.0
Gateway...........................: 192.168.1.1
Physical address..................: 54-89-98-C8-2B-C3
DNS server........................: 8.8.8.8
4.DHCP三层交换上的配置
//L3SW配置 ，其主要配置是针对vlan的虚接口进行配置的，其配置与路由器上的配置类似。
[L3SW]dhcp enable
[L3SW]ip pool p5
[L3SW-ip-pool-p5]network 192.168.5.0 mask 24
[L3SW-ip-pool-p5]gateway-list 192.168.5.1
[L3SW-ip-pool-p5]dns-list 8.8.8.8
[L3SW-ip-pool-p5]lease day 1 hour 0 minute 0
[L3SW]ip pool p10
[L3SW-ip-pool-p10]network 192.168.10.0 mask 24
[L3SW-ip-pool-p10]gateway-list 192.168.10.1
[L3SW-ip-pool-p10]dns-list 8.8.8.8
[L3SW-ip-pool-p10]lease day 1 hour 0 minute 0
[L3SW]vlan batch 5 10
[L3SW]interface Vlanif 5
[L3SW-Vlanif5]ip address 192.168.5.1 24
[L3SW-Vlanif5]dhcp select global
[L3SW]interface Vlanif 10
[L3SW-Vlanif10]ip address 192.168.10.1 24
[L3SW-Vlanif10]dhcp select global
[L3SW]interface GigabitEthernet0/0/1
[L3SW-GigabitEthernet0/0/1]port link-type trunk
[L3SW-GigabitEthernet0/0/1]port trunk allow-pass vlan 5 10
//二层交换机配置 主要是配置相关的连接类型，所属vlan
[SW]vlan batch 5 10
[SW]interface Ethernet0/0/1
[SW-Ethernet0/0/1]port link-type access
[SW-Ethernet0/0/1]port default vlan 5
[SW]interface Ethernet0/0/2
[SW-Ethernet0/0/2]port link-type access
[SW-Ethernet0/0/2]port default vlan 10
[SW]interface GigabitEthernet 0/0/1
[SW-GigabitEthernet0/0/1]port link-type trunk
[SW-GigabitEthernet0/0/1]port trunk allow-pass vlan 5 10
//PC机上获取的相关IP信息
PC>ipconfig /renew
IP Configuration
Link local IPv6 address...........: fe80::5689:98ff:feee:1533
IPv6 address......................: :: / 128
IPv6 gateway......................: ::
IPv4 address......................: 192.168.5.253 //vlan5相关的IP地址信息
Subnet mask.......................: 255.255.255.0
Gateway...........................: 192.168.5.1
Physical address..................: 54-89-98-EE-15-33
DNS server........................: 8.8.8.8
PC>ipconfig /renew
IP Configuration
Can't get IP!
Link local IPv6 address...........: fe80::5689:98ff:fe4d:6ce6
IPv6 address......................: :: / 128
IPv6 gateway......................: ::
IPv4 address......................: 192.168.10.254 //vlan10相关的IP地址信息
Subnet mask.......................: 255.255.255.0
Gateway...........................: 192.168.10.1
Physical address..................: 54-89-98-4D-6C-E6
DNS server........................: 8.8.8.8
