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在三层交换机配置DHCP的方法分享

2020-03-07 21:36:42
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通过本实验掌握,如何在Cisco Catalyst 3550交换机来配置DHCP服务,实现对内网主机分配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,根据需求,大多是在接入层或者汇聚层多层交换机来配置的,可以同时实现DHCP Snooping等技术。 
三层交换机,DHCP 


实验过程:

第一步:Catalyst 3550底层配置 
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 
//连接终端的接口下,开启portfast特性,跳过生成树的选举,接口立即进入转发状态 
%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: 开启DHCP服务,定义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,名称为可以是任意字符 
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,全国各地市不一样的) 
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 infinite 
Switch_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。如果这些地址被分配给PC使用,就有可能造成网络中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,并启用SVI接口 

复制代码
代码如下:

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. 
//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,默认情况下Cisco Catalyst交换机所有的物理接口都属于VLAN1,此地址也就是PC网关地址。 
Switch_Dhcp(config-if)#ip add 192.168.0.1 255.255.255.0 
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:查看当前交换机配置文件 

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代码如下:

//验证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:此时将PC1的网线插入Catalyst 3550 的F0/1接口,并在PC上查看IP地址获得信息。PC上的本地连接,TCP/IP 设置为自动获得IP地址形式。 
PC上查看方法:开始-运行-cmd-ipconfig/all 
三层交换机,DHCP


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:查看交换机DHCP 动态绑定,以及交换机DHCP Server状态信息 

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代码如下:

//查看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,以及PC的MAC地址等 
Switch_Dhcp#show ip dhcp binding 
IP address Client-ID/ Lease expiration Type 
Hardware address 
192.168.0.2 0100.16d3.249f.fd Infinite Automatic 
//查看DHCP服务器工作状态 
Switch_Dhcp#show ip dhcp server statistics 
Memory usage 5661 
Address pools 1 
Database agents 0 
Automatic bindings 1 
Manual bindings 0 
Expired bindings 0 
Malformed messages 0 
Message Received 
BOOTREQUEST 0 
DHCPDISCOVER 2 
DHCPREQUEST 3 
DHCPDECLINE 0 
DHCPRELEASE 0 
DHCPINFORM 3 
Message Sent 
BOOTREPLY 0 
DHCPOFFER 2 
DHCPACK 6 
DHCPNAK 0 
Switch_Dhcp# 
Switch_Dhcp#clear ip dhcp binding * 


第七步:使用debug 调试命令查看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 
此时查看交换机日志信息 

复制代码
代码如下:

Switch_Dhcp#debug ip dhcp server events 
01:13:12: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up 
Switch_Dhcp# 
01:13:13: DHCPD: DHCPDISCOVER received from client 0100.16d3.249f.fd on interface Vlan1. 
Switch_Dhcp# 
01:13:20: DHCPD: assigned IP address 192.168.0.3 to client 0100.16d3.249f.fd. 
01:13:20: DHCPD: Sending DHCPOFFER to client 0100.16d3.249f.fd (192.168.0.3). 
01:13:20: DHCPD: broadcasting BOOTREPLY to client 0016.d324.9ffd. 
01:13:20: DHCPD: DHCPREQUEST received from client 0100.16d3.249f.fd. 
01:13:20: DHCPD: Sending DHCPACK to client 0100.16d3.249f.fd (192.168.0.3). 
01:13:20: DHCPD: broadcasting BOOTREPLY to client 0016.d324.9ffd. 
Switch_Dhcp# 
01:13:23: DHCPD: DHCPINFORM received from client 0100.16d3.249f.fd (192.168.0.3). 
01:13:23: DHCPD: Sending DHCPACK to client 0100.16d3.249f.fd (192.168.0.3). 
01:13:23: DHCPD: unicasting BOOTREPLY to client 0016.d324.9ffd (192.168.0.3). 


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