場景:用路由器模擬PC以及DHCP_SERVER,在同一網段配置DHCP。將PC接口配置爲動態獲取地址時,PC會廣播DHCP_DISCOVER報文發現DHCP服務器,這時可能有多個DHCP服務器收到報文後會廣播回覆DHCP_OFFER報文,而PC只會選取一個然後廣播DHCP_REQUEST告訴服務器要這個地址,服務器檢查可行就回復DHCP_Ack,這樣地址就獲取完成。
操作步驟:
步驟一:按照拓撲搭建實驗環境
步驟二:用路由器模擬PC,關閉路由功能並將接口配置爲動態獲取IP
PC(config)#no iprouting //關閉路由功能
PC(config)#intf0/0
PC(config-if)#ip add
PC(config-if)#ipaddress dh
PC(config-if)#ipaddress dhcp //將接口配置爲動態獲取IP
步驟三:在DHCP_SERVER配置接口地址,DHCP地址池以及租期等信息
DHCP_SERVER(config)#
DHCP_SERVER(config)#intf0/0
DHCP_SERVER(config-if)#ipadd 192.168.10.254 255.255.255.0
DHCP_SERVER(config-if)#
DHCP_SERVER(config-if)#nosh
DHCP_SERVER(config)#ipdhcp pool dhcp_pool_1 // 配置DHCP的地址池名字
DHCP_SERVER(dhcp-config)#network192.168.10.0 255.255.255.0 // 配置DHCP地址範圍
DHCP_SERVER(dhcp-config)#default-router192.168.10.254 //配置分配給主機的網關
DHCP_SERVER(dhcp-config)#lease0 8 0 //租期爲0天8小時0分鐘
DHCP_SERVER(dhcp-config)#ex
DHCP_SERVER(config)#ipdhcp excluded-address 192.168.10.250 192.168.10.254 //地址池中
需要排除的地址
步驟四:使用Wireshark,觀察DHCP的獲取過程
步驟五:查看接口地址獲取情況
PC#sh ip int b
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 192.168.10.2 YES DHCP up up
FastEthernet1/0 unassigned YES unset administratively down down
配置文件
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PC#sh run
Buildingconfiguration...
version 12.4
no ip routing
!
!
……
!
interface FastEthernet0/0
ip address dhcp
no ip route-cache
duplex auto
speed auto
!
!
……
!
end
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DHCP_SERVER#sh run
Buildingconfiguration...
!
version 12.4
!
hostname DHCP_SERVER
!
!
!
ip cef
no ip dhcp use vrfconnected
ip dhcpexcluded-address 192.168.10.250 192.168.10.254
!
ip dhcp pooldhcp_pool_1
network 192.168.10.0 255.255.255.0
default-router 192.168.10.254
lease 0 8
!
!
interfaceFastEthernet0/0
ip address 192.168.10.254 255.255.255.0
duplex auto
speed auto
!
………
!
!
end
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