通过本实验学会，怎么样在Cisco Catalyst 3550交换机来配置DHCP服务，达成对内网主机分配IP地址，网关，DNS，WINS，租期，域名等。可能你之前是在windows Server服务器或者Cisco Router 部署过DHCP,但在工程项目中，依据需要，大多是在接入层或者汇聚层多层交换机来配置的，可以同时达成DHCP Snooping等技术。

实验过程：

第一步：Catalyst 3550底层配置Switch(config)#no ip do loSwitch(config)#line con 0Switch(config-line)#no exec-tSwitch(config-line)#logg synSwitch(config-line)#host Switch_DhcpSwitch_Dhcp(config)#int f0/1Switch_Dhcp(config-if)#no shSwitch_Dhcp(config-if)#spanning-tree portfast//连接终端的接口下，开启portfast特质，跳过生成树的选举，接口立即进入转发状况%Warning: portfast should only be enabled on ports connected to a singlehost. Connecting hubs, concentrators, switches, bridges, etc... to thisinterface when portfast is enabled, can cause temporary bridging loops.Use with CAUTION%Portfast has been configured on FastEthernet0/1 but will onlyhave effect when the interface is in a non-trunking mode.Switch_Dhcp(config-if)#end第二步: 开启DHCP服务，概念分配地址池范围及掩码，网关，DNS，域名，租期等//全局下开启DHCP服务，该服务默认是关闭的Switch_Dhcp(config)#service dhcp//关闭DHCP分配冲突，日志记录消息Switch_Dhcp(config)#no ip dhcp conflict logging//创建DHCP地址池，名字为可以是任意字符Switch_Dhcp(config)#ip dhcp pool cisco//指定要通过DHCP分配的网段和掩码，还有另外一种写法（192.168.0.0 255.255.255.0）Switch_Dhcp(dhcp-config)#network 192.168.0.0 /24//指定分配的网关地址Switch_Dhcp(dhcp-config)#default-router 192.168.0.1//指定DHCP域名，域名可以为任意字符Switch_Dhcp(dhcp-config)#domain-name www.cisco.com.cn//指定PC通过DHCP分配到DNS地址，（这里指定的是当地电信部门的真实地址，全国各地市不同的）Switch_Dhcp(dhcp-config)#dns 218.30.19.40 61.134.1.4//netbios服务器地址，可选的配置Switch_Dhcp(dhcp-config)#netbios-name-server 192.168.0.10//指定通过DHCP分配到地址，租期为永久Switch_Dhcp(dhcp-config)#lease infiniteSwitch_Dhcp(dhcp-config)#end//指定不通过DHCP 地址池中分配的地址，也就是排除的地址。假如这类地址被分配给PC用，就大概导致互联网中IP地址冲突。如：192.168.0.1 是网关地址，该地址只能是分配所有PC做网关地址，不可以做IP地址用。所以要排除。Switch_Dhcp(config)#ip dhcp excluded-address 192.168.0.1Switch_Dhcp(config)# ip dhcp excluded-address 192.168.0.10第三步：查询VLAN信息，并启用SVI接口

复制代码代码如下:

Switch_Dhcp#show vlan briefVLAN Name Status Ports---- -------------------------------- --------- -------------------------------1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4Fa0/5, Fa0/6, Fa0/7, Fa0/8Fa0/9, Fa0/10, Fa0/11, Fa0/12Fa0/13, Fa0/15, Fa0/16, Fa0/17Fa0/18, Fa0/19, Fa0/20, Fa0/21Fa0/22, Fa0/23, Fa0/24, Gi0/1Gi0/21002 fddi-default act/unsup1003 token-ring-default act/unsup1004 fddinet-default act/unsup1005 trnet-default act/unsupSwitch_Dhcp#conf tEnter configuration commands, one per line. End with CNTL/Z.//进入管理VLAN1 下，启用SVI功能Switch_Dhcp(config)#int vlan 1//配置VLAN的地址为192.168.0.1 掩码为24位，默认状况下Cisco Catalyst交换机所有些物理接口都是VLAN1，此地址也就是PC网关地址。Switch_Dhcp(config-if)#ip add 192.168.0.1 255.255.255.0Switch_Dhcp(config-if)#no shSwitch_Dhcp(config-if)#endSwitch_Dhcp#00:09:07: %SYS-5-CONFIG_I: Configured from console by consoleSwitch_Dhcp#00:09:08: %LINK-3-UPDOWN: Interface Vlan1, changed state to up00:09:09: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to

第四步：查询目前交换机配置文件

复制代码代码如下:

//验证DHCP的配置信息Switch_Dhcp#sh run | begin ip dhcpno ip dhcp conflict loggingip dhcp excluded-address 192.168.0.1ip dhcp excluded-address 192.168.0.10!ip dhcp pool cisconetwork 192.168.0.0 255.255.255.0default-router 192.168.0.1domain-name www.cisco.com.cndns-server 218.30.19.40 61.134.1.4netbios-name-server 192.168.0.10lease infiniteinterface Vlan1ip address 192.168.0.1 255.255.255.0

第五步：此时将PC1的网线插入Catalyst 3550 的F0/1接口，并在PC上查询IP地址获得信息。PC上的当地连接，TCP/IP 设置为自动获得IP地址形式。PC上查询办法：开始-运行-cmd-ipconfig/all

从以上信息可以得出，PC已经能从DHCP服务器获得IP地址等信息，实验现象成功。

第六步：查询交换机DHCP 动态绑定，与交换机DHCP Server状况信息

复制代码代码如下:

//查询DHCP动态绑定信息，从这里可以看到PC，从DHCP地址池中的得到IP地址，与PC的MAC地址等Switch_Dhcp#show ip dhcp bindingIP address Client-ID/ Lease expiration TypeHardware address192.168.0.2 0100.16d3.249f.fd Infinite Automatic//查询DHCP服务器工作状况Switch_Dhcp#show ip dhcp server statisticsMemory usage 5661Address pools 1Database agents 0Automatic bindings 1Manual bindings 0Expired bindings 0Malformed messages 0Message ReceivedBOOTREQUEST 0DH下载成本ISCOVER 2DHCPREQUEST 3DH下载成本ECLINE 0DHCPRELEASE 0DH安装成本NFORM 3Message SentBOOTREPLY 0DHCPOFFER 2DH行动成本CK 6DHCPNAK 0Switch_Dhcp#Switch_Dhcp#clear ip dhcp binding *

第七步：用debug 调试命令查询PC申请IP地址过程（DHCP工作过程）在PC上：开始-运行-cmd-ipconfig /release (释放获得IP地址)重新申请IP地址ipconfig /renew此时查询交换机日志信息

复制代码代码如下:

Switch_Dhcp#debug ip dhcp server events01:13:12: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to upSwitch_Dhcp#01:13:13: DH下载成本: DH下载成本ISCOVER received from client 0100.16d3.249f.fd on interface Vlan1.Switch_Dhcp#01:13:20: DH下载成本: assigned IP address 192.168.0.3 to client 0100.16d3.249f.fd.01:13:20: DH下载成本: Sending DHCPOFFER to client 0100.16d3.249f.fd (192.168.0.3).01:13:20: DH下载成本: broadcasting BOOTREPLY to client 0016.d324.9ffd.01:13:20: DH下载成本: DHCPREQUEST received from client 0100.16d3.249f.fd.01:13:20: DH下载成本: Sending DH行动成本CK to client 0100.16d3.249f.fd (192.168.0.3).01:13:20: DH下载成本: broadcasting BOOTREPLY to client 0016.d324.9ffd.Switch_Dhcp#01:13:23: DH下载成本: DH安装成本NFORM received from client 0100.16d3.249f.fd (192.168.0.3).01:13:23: DH下载成本: Sending DH行动成本CK to client 0100.16d3.249f.fd (192.168.0.3).01:13:23: DH下载成本: unicasting BOOTREPLY to client 0016.d324.9ffd (192.168.0.3).

本文源于 “王万利的博客” 博客

Tags：地址交换机分配