單臂路由和DHCP實驗

1、需求一：實施單臂路由實驗（小型網(wǎng)絡）通過在交換鏈路實施trunk和路由器的子接口功能，實現(xiàn)屬于小型網(wǎng)絡中，屬于不同vlan的 兩臺PC的通信PC之間是通過兩臺交換機的e0/2 口來通信的，sw2的e0/3 口為BLK狀態(tài)；（我沒有修改到達e0/3的開銷，故e0/2 口是根端口，可以接收和轉發(fā)數(shù)據(jù)）1）那么首先，交換之間（2 口之間）配置trunk鏈路：先封裝dotlq，再劃到trunk上，但不劃具體的vlan （這里不是配置本征vlan實驗，不要配置允許通過哪些個vlan的流量）sw1到Branch之間也實施trunk，即交換機上一端封裝dot1q，并劃到trunk上，也不劃vlan；路由器上

2、也封裝dot1q，這一步是關鍵，路由器會通過dot1q封裝來識別流量，配置的方式 和交換機上不同再分別將 sw1 和 sw2 的 1 口 access 到 vlan10 和 vlan202）然后，切記，PC1和PC2的網(wǎng)關的設置，如果不關閉PC的路由功能，那么pc1（路由器）到pc2 （路由器）是沒有路由的（需要配置路由，可能是靜態(tài)），數(shù)據(jù)包是不通的設置完畢后，需要測試網(wǎng)關是否可以ping通，這一步也是非常重要3）最后，測試PC1到PC2是否可以ping通1）sw1（config）#int e0/2sw1（config-if）#switchport trunk encapsulation do

3、t1qsw1（config-if）#switchport mode trunksw2（config）#int e0/2sw2（config-if）#switchport trunk encapsulation dot1qsw2（config-if）#switchport mode trunkBranch(config)#default int e0/0Interface Ethernet0/0 set to default configurationBranch(config)#do sh run int e0/0Building configuration.Current configura

4、tion : 44 bytes!interface Ethernet0/0no ip addressendBranch(config)#int e0/0.10Branch(config-subif)#encapsulation dotlQ 10Branch(config-subif)#ip address 10.1.10.254 255.255.255.0Branch(config-subif)#exiBranch(config)#int e0/0.20Branch(config-subif)#encapsulation dot1Q 20Branch(config-subif)#ip addr

5、ess 10.1.20.254 255.255.255.0 sw1(config)#int e0/1sw1(config-if)#switchport mode accesssw1(config-if)#switchport access vlan 10sw2(config)#int e0/1sw2(config-if)#switchport mode accesssw2(config-if)#switchport access vlan 20PC1(config)#int e0/1PC1(config-if)#ip address 10.1.10.100PC1(config-if)#ip a

6、ddress 10.1.10.100 255.255.255.0PC1(config-if)#exiPC1(config)#no ip routingPC1(config)#default gateway 10.1.10.254pc2(config)#default int e0/1Interface Ethernet0/1 set to default configuration pc2(config)#no ip routingpc2(config)#default gateway 10.1.20.254 pc2(config)#int e0/1pc2(config-if)#ip addr

7、ess 10.1.20.100 255.255.255.0 3)測試ping網(wǎng)關一開始ping2個網(wǎng)關均沒ping通檢查，pc1設置，沒問題路由器設置也沒問題最后發(fā)現(xiàn)，問題出在將sw1的e0/1劃到trunk去了(應該劃到vlan10的)，并且e0/0 口也 沒有配置任何東西；清除這2個端口上的所有配置，重新操作后，發(fā)現(xiàn)可以ping通了sw1(config)#default int e0/1Interface Ethernet0/1 set to default configuration*Mar 7 09:25:03.528: %LINK-3-UPDOWN: Interface Ethern

8、et0/1, changed state to up*Mar 7 09:25:04.529: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0/1, changed state to upsw1(config)#int e0/1sw1(config-if)#switchport mode accesssw1(config-if)#switchport access vlan 10sw1(config-if)#exisw1(config)#default int e0/0Interface Ethernet0/0 set to d

9、efault configuration*Mar 7 09:26:27.190: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet。/。, changed state to down*Mar 7 09:26:30.194: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0/0, changed state to up sw1(config)#int e0/0sw1(config-if)#switchport trunk encapsulation dot1qsw1(

10、config-if)#switchport mode trunkPC1#ping 10.1.20.254Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 10.1.20.254, timeout is 2 seconds:.!Success rate is 20 percent (1/5), round-trip min/avg/max = 5023/5023/5023 msPC1#ping 10.1.10.254Type escape sequence to abort.Sending 5, 100-byte IC

11、MP Echos to 10.1.10.254, timeout is 2 seconds:!Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms這里我有疑問，求解析：pc1 為什么可以 ping 通 10.1.20.254pc1上的arp表象中為什么不會有10.1.20.254需求二：在小型網(wǎng)絡里實施DHCPBranch作為DHCP服務器，并為PC1和PC2都分配ip在小型網(wǎng)絡中，配置靜態(tài)IP地址，有很多缺點，比如可能會出現(xiàn)地址沖突(兩臺設備配置 了同一個ip)；工作量很大并且沒有擴展性可言；于是，在網(wǎng)絡中需

12、要動態(tài)主機控制協(xié)議(DHCP)，它可以根據(jù)用戶的vlan屬性，分配ip地址1)首先，cisco設備中DHCP是默認開啟的，關閉是Branch(config)#no service dhcpBranch(config)#ip dhcp pool yanghaibo配置 vlan10 的地址池Branch(dhcp-config)#network 10.1.10.0 /24/配置子網(wǎng)Branch(dhcp-config)#default-router 10.1.10.254/配置默認網(wǎng)關Branch(dhcp-config)#dns-server 114.114.114.114/配置 DNS 服務

13、器Branch(dhcp-config)#lease 1 16/配置租用日期Branch(dhcp-config)#exiBranch(config)#ip dhcp excluded-address 10.1.10.101 10.1.10.254/排除一些地址Pc1上這樣配置PC1#conftEnter configuration commands, one per line. End with CNTL/Z.PC1(config)#int e0/1PC1(config-if)#ip address dhcpPC1(config-if)#在 Branch 上敲了 debug DHCP det

14、ail，結果在 pc1 上有調(diào)試信息，由于(PC1(config-if)#ip address dhcp)敲了 2次，pc1被自動分配了 2次地址：*Mar 7 10:11:46.172: %DHCP-6-ADDRESS_ASSIGN: Interface Ethernet0/1 assigned DHCPaddress 10.1.10.1, mask 255.255.255.0, hostname PC1PC1(config-if)#ip address dhcpPC1(config-if)#*Mar 7 10:12:08.463: %DHCP-6-ADDRESS_ASSIGN: Inter

15、face Ethernet0/1 assigned DHCPaddress 10.1.10.2, mask 255.255.255.0, hostname PC1上面是vlan1的地址池Branch(config)#ip dhcp pool yanghaibo 2Branch(dhcp-config)#network 10.1.20.0 /24Branch(dhcp-config)#default-router 10.1.20.254Branch(dhcp-config)#dns-server 114.114.114.114Branch(dhcp-config)#lease 1 16Branc

16、h(dhcp-config)#exiBranch(config)#ip dhcp excluded-address 10.1.20.101 10.1.20.254 pc2enpc2#conf tEnter configuration commands, one per line. End with CNTL/Z.pc2(config)#int e0/1pc2(config-if)#ip address dhcppc2(config-if)#*Mar 7 10:18:18.537: %DHCP-6-ADDRESS_ASSIGN: Interface Ethernet0/1 assigned DH

17、CP address 10.1.20.1, mask 255.255.255.0, hostname pc2在pc2上開啟debug dhcp再次敲自動分配地址的命令，得到如下調(diào)試信息：pc2#debug dhcpDHCP client activity debugging is on pc2(config-if)#ip address dhcp*Mar 7 10:20:31.942: DHCP: Sending notification of TERMINATION:*Mar 7 10:20:31.942: Address 10.1.20.1 mask 255.255.255.0*Mar 7

18、 10:20:31.942: DHCP: Client socket is opened*Mar 7 10:20:31.942: DHCP: SRelease attempt # 1 for entry:*Mar 7 10:20:31.942: DHCP: SRelease placed Server ID option: 10.1.20.254*Mar 7 10:20:31.942: DHCP: SRelease: 279 bytes*Mar 7 10:20:33.108: DHCP: SRelease attempt # 2 for entry:*Mar 7 10:20:33.108: D

19、HCP: SRelease placed Server ID option: 10.1.20.254*Mar 7 10:20:33.108: DHCP: SRelease: 279 bytes*Mar 7 10:20:35.129: DHCP: SRelease attempt # 3 for entry:*Mar 7 10:20:35.129: DHCP: SRelease placed Server ID option: 10.1.20.254*Mar 7 10:20:35.129: DHCP: SRelease: 279 bytes pc2(config-if)#*Mar 7 10:20

20、:37.489: RAC: DHCP stopped on interface Ethernet0/1*Mar 7 10:20:37.489: DHCP: DHCP client process started: 10*Mar 7 10:20:37.494: RAC: Starting DHCP discover on Ethernet0/1*Mar 7 10:20:37.494: DHCP: Try 1 to acquire address for Ethernet0/1*Mar 7 10:20:37.507: DHCP: allocate request*Mar 7 10:20:37.50

21、7: DHCP: zapping entry in DHC_PURGING state for Et0/1*Mar 7 10:20:37.507: DHCP: deleting entry B4406420 10.1.20.1 from list*Mar 7 10:20:37.507: DHCP: new entry. add to queue, interface Ethernet0/1*Mar 7 10:20:37.507: DHCP: SDiscover attempt # 1 for entry:*Mar 7 10:20:37.507: DHCP: SDiscover: sending

22、 292 byte length DHCP packet pc2(config-if)#*Mar 7 10:20:37.507: DHCP: SDiscover 292 bytes*Mar 7 10:20:37.507:Bcast on Ethernet0/1 interface from 0.0.0.0pc2(config-if)#*Mar 7 10:20:39.538: DHCP: Received a BOOTREP pkt*Mar 7 10:20:39.538: DHCP: offer received from 10.1.20.254*Mar 7 10:20:39.538: DHCP: SRequest attempt # 1 for entry:*Mar 7 10:20:39.538: DHCP: