實驗過程： 第一步：Catalyst 3550底層配置
Switch(config)#no ip do lo
Switch(config)#line con 0
Switch(config-line)#no exec-t
Switch(config-line)#logg syn
Switch(config-line)#host Switch_Dhcp
Switch_Dhcp(config)#int f0/1
Switch_Dhcp(config-if)#no sh
Switch_Dhcp(config-if)#spanning-tree portfast
//連接終端的接口下，開啟portfast特性，跳過生成樹的選舉，接口立即進入轉發狀態
%Warning: portfast should only be enabled on ports connected to a single
host. Connecting hubs, concentrators, switches, bridges, etc... to this
interface when portfast is enabled, can cause temporary bridging loops.
Use with CAUTION
%Portfast has been configured on FastEthernet0/1 but will only
have effect when the interface is in a non-trunking mode.
Switch_Dhcp(config-if)#end
第二步: 開啟DHCP服務，定義分配地址池范圍及掩碼，網關，DNS，域名，租期等
//全局下開啟DHCP服務，該服務默認是關閉的
Switch_Dhcp(config)#service dhcp
//關閉DHCP分配沖突，日志記錄消息
Switch_Dhcp(config)#no ip dhcp conflict logging
//創建DHCP地址池，名稱為可以是任意字符
Switch_Dhcp(config)#ip dhcp pool cisco
//指定要通過DHCP分配的網段和掩碼，還有另外一種寫法（192.168.0.0 255.255.255.0）
Switch_Dhcp(dhcp-config)#network 192.168.0.0 /24
//指定分配的網關地址
Switch_Dhcp(dhcp-config)#default-router 192.168.0.1
//指定DHCP域名，域名可以為任意字符
Switch_Dhcp(dhcp-config)#domain-name www.cisco.com.cn
//指定PC通過DHCP分配到DNS地址，（這里指定的是當地電信部門的真實地址，全國各地市不一樣的）
Switch_Dhcp(dhcp-config)#dns 218.30.19.40 61.134.1.4
//netbios服務器地址，可選的配置
Switch_Dhcp(dhcp-config)#netbios-name-server 192.168.0.10
//指定通過DHCP分配到地址，租期為永久
Switch_Dhcp(dhcp-config)#lease infinite
Switch_Dhcp(dhcp-config)#end
//指定不通過DHCP 地址池中分配的地址，也就是排除的地址。如果這些地址被分配給PC使用，就有可能造成網絡中IP地址沖突。如：192.168.0.1 是網關地址，該地址只能是分配所有PC做網關地址，不能做IP地址使用。所以要排除。
Switch_Dhcp(config)#ip dhcp excluded-address 192.168.0.1
Switch_Dhcp(config)# ip dhcp excluded-address 192.168.0.10
第三步：查看VLAN信息，并啟用SVI接口
Switch_Dhcp#show vlan brief
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4
Fa0/5, Fa0/6, Fa0/7, Fa0/8
Fa0/9, Fa0/10, Fa0/11, Fa0/12
Fa0/13, Fa0/15, Fa0/16, Fa0/17
Fa0/18, Fa0/19, Fa0/20, Fa0/21
Fa0/22, Fa0/23, Fa0/24, Gi0/1
Gi0/2
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup
Switch_Dhcp#conf t
Enter configuration commands, one per line. End with CNTL/Z.
//進入管理VLAN1 下，啟用SVI功能
Switch_Dhcp(config)#int vlan 1
//配置VLAN的地址為192.168.0.1 掩碼為24位，默認情況下Cisco Catalyst交換機所有的物理接口都屬于VLAN1，此地址也就是PC網關地址。
Switch_Dhcp(config-if)#ip add 192.168.0.1 255.255.255.0
Switch_Dhcp(config-if)#no sh
Switch_Dhcp(config-if)#end
Switch_Dhcp#
00:09:07: %SYS-5-CONFIG_I: Configured from console by console
Switch_Dhcp#
00:09:08: %LINK-3-UPDOWN: Interface Vlan1, changed state to up
00:09:09: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to
第四步：查看當前交換機配置文件
//驗證DHCP的配置信息
Switch_Dhcp#sh run | begin ip dhcp
no ip dhcp conflict logging
ip dhcp excluded-address 192.168.0.1
ip dhcp excluded-address 192.168.0.10
!
ip dhcp pool cisco
network 192.168.0.0 255.255.255.0
default-router 192.168.0.1
domain-name www.cisco.com.cn
dns-server 218.30.19.40 61.134.1.4
netbios-name-server 192.168.0.10
lease infinite
interface Vlan1
ip address 192.168.0.1 255.255.255.0
第五步：此時將PC1的網線插入Catalyst 3550 的F0/1接口，并在PC上查看IP地址獲得信息。PC上的本地連接，TCP/IP 設置為自動獲得IP地址形式。
PC上查看方法：開始-運行-cmd-ipconfig/all
