在三層交換機(jī)配置DHCP的方法分享

發(fā)布時(shí)間：2012-09-20 15:37:19 作者：佚名

通過(guò)本實(shí)驗(yàn)掌握，如何在Cisco Catalyst 3550交換機(jī)來(lái)配置DHCP服務(wù)，實(shí)現(xiàn)對(duì)內(nèi)網(wǎng)主機(jī)分配IP地址，網(wǎng)關(guān)，DNS，WINS，租期，域名等

通過(guò)本實(shí)驗(yàn)掌握，如何在Cisco Catalyst 3550交換機(jī)來(lái)配置DHCP服務(wù)，實(shí)現(xiàn)對(duì)內(nèi)網(wǎng)主機(jī)分配IP地址，網(wǎng)關(guān)，DNS，WINS，租期，域名等。可能你之前是在windows Server服務(wù)器或者Cisco Router 部署過(guò)DHCP,但在工程項(xiàng)目中，根據(jù)需求，大多是在接入層或者匯聚層多層交換機(jī)來(lái)配置的，可以同時(shí)實(shí)現(xiàn)DHCP Snooping等技術(shù)。

實(shí)驗(yàn)過(guò)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(guò)生成樹的選舉，接口立即進(jìn)入轉(zhuǎn)發(fā)狀態(tài)
%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(wù)，定義分配地址池范圍及掩碼，網(wǎng)關(guān)，DNS，域名，租期等
//全局下開啟DHCP服務(wù)，該服務(wù)默認(rèn)是關(guān)閉的
Switch_Dhcp(config)#service dhcp
//關(guān)閉DHCP分配沖突，日志記錄消息
Switch_Dhcp(config)#no ip dhcp conflict logging
//創(chuàng)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(guò)DHCP分配的網(wǎng)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(wǎng)關(guān)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(guò)DHCP分配到DNS地址，（這里指定的是當(dāng)?shù)仉娦挪块T的真實(shí)地址，全國(guó)各地市不一樣的）
Switch_Dhcp(dhcp-config)#dns 218.30.19.40 61.134.1.4
//netbios服務(wù)器地址，可選的配置
Switch_Dhcp(dhcp-config)#netbios-name-server 192.168.0.10
//指定通過(guò)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(guò)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(wǎng)絡(luò)中IP地址沖突。如：192.168.0.1 是網(wǎng)關(guān)地址，該地址只能是分配所有PC做網(wǎng)關(guān)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

復(fù)制代碼

代碼如下:

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.
//進(jìn)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(rèn)情況下Cisco Catalyst交換機(jī)所有的物理接口都屬于VLAN1，此地址也就是PC網(wǎng)關(guān)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(dāng)前交換機(jī)配置文件

復(fù)制代碼

代碼如下:

//驗(yàn)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(shí)將PC1的網(wǎng)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(shè)置為自動(dòng)獲得IP地址形式。
PC上查看方法：開始-運(yùn)行-cmd-ipconfig/all

從以上信息可以得出，PC已經(jīng)能從DHCP服務(wù)器獲得IP地址等信息，實(shí)驗(yàn)現(xiàn)象成功。

第六步：查看交換機(jī)DHCP 動(dòng)態(tài)綁定，以及交換機(jī)DHCP Server狀態(tài)信息

復(fù)制代碼

代碼如下:

//查看DHCP動(dòng)態(tài)綁定信息，從這里可以看到PC，從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服務(wù)器工作狀態(tài)
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 調(diào)試命令查看PC申請(qǐng)IP地址過(guò)程（DHCP工作過(guò)程）
在PC上：開始-運(yùn)行-cmd-ipconfig /release (釋放獲得IP地址)
重新申請(qǐng)IP地址ipconfig /renew
此時(shí)查看交換機(jī)日志信息

復(fù)制代碼

代碼如下:

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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