cisco ccnp 642-832 TSHOOT(Troubleshooting) 万金油!
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642-832题库万金油详细解法 ASW1------port security access vlan switch to switch connectivity R1------IPv4 OSPF BGP NAT IPv4 layer 3 security DSW1-----vlan ACL/port ACL HSRP R4------IPv4 EIGRP routing IPv4 router redistribute IP DHCP server IPv4 EIGRP routing
R2------IPv6 OSPF routing 第一部分:找到两个“明显提示HSRP&IPv6” 一、解决HSRP和IPv6 所有题一题一题打开,打开后按abort取消,HSRP 和IPV6的问题明显会不同,解决掉。 在题干中找“HSRP” “IPv6”关键字眼,用笔记好题号 在3层拓扑图中,用client1 ping 209.65.200.241(web server)能ping通就是IPV6或者HSRP 1、 HSRP:(Q20-22)在IPv6--3层拓扑图中。 DSW1上sh run,看到standby条目(在找答案选项的时候,不确认的可以看看)show standby brief------看到状态没有up!
(1)DSW1, (2)HSRP, (3)Under the interface vlan 10 configuration delete the standby 10 track 1 decrement 60 command and enter the standby 10 track 10 decrement 60 command. 解释:由特定路由条目的metric值来决定track项目的down或up,从而触发对standby的priority值减小或增加。此题中,可能没有到达10.1.21.128/16网段的路由,所以trace1的metric肯定大于2,那么vlan10关联了track1的DSW1-vlan10的HSRPPriority=200-60=140,则HSRP-active就变成了DSW2。 当vlan10关联了track10时,由于10.2.21.128/255.255.255.0是R4-lo0,所以track10的metric小于63,那么track10为up状态,DSW1-vlan10的priority=200,DSW1为active。 V200:In this case we know that the problem is with HSRP and that DSW1 will not become the active router.Since we know that HSRP communication is working between DSW1 and DSW2, we can deduce that theproblem must be with DSW1. 2、 IPV6:(Q56-58)在IPv6--3层拓扑图中。 R2或R3上sh ipv6 router,只有直连和L 链路本地,没有任何ospf路由。 R2、R3上sh run,比较下其中一个少了一条命令。
(1)R2,或R3 (2)IPv6 OSPF Routing, (3)Under the interface Serial 0/0/0.23 configuration enter the ipv6 ospf 6 area 0 command. 解释:Unlike OSPF on IPv4 where networks are added under the routing process, IPv6 needs OSPFv3 enabled on a per-interface basis. This has been done on the R3 connection to R2, but not on the R2 connection back to R3. We will need to add the "ipv6 ospf 6 area 0" configuration command to the s0/0/0/0.23 interface of R2.
第二部分:统一错误特点------依次在client 1 上ipconfig, 找到4个错误的ip:169.X.X.X(DHCP、port-security、access-vlan、trunk-allowed) 每个TT依次在client 1 输入ipconfig,看下IP,有4个题的IP是169开头的。 记下这4题编号,其中1个是R4有问题,剩下3个是ASW1有问题。 1、 DHCP:(Q50-52)在2层拓扑图中。 现象:C1和C2获得169.x.x.x.地址,互相可以ping通,但是ping不通DSW1&FTP。 在这4道题上,分别在R4上show run,看到有一个明显dhcp范围和其余3个不同,ip dhcp excluded-address 10.2.1.1 10.2.1.253(注意IP范围),确认为DHCP错误。
(1)R4, (2)IP DHCP Server, (3)Under the global configuration, issue the no ip dhcp excluded-address 10.2.1.1 10.2.1.253 command and enter the ip dhcp excluded-address 10.2.1.1 10.2.1.2 command. 解释:此题的dhcp规则中ip dhcp excluded-address 10.2.1.1 10.2.1.253将整个10.2.1.0/24的地址都排除了,导致C1 C2都无法获得dhcp的地址。 2 、Port Security:(Q35-37)在2层拓扑图中。 现象:C1获得169.x.x.x地址,ping不通C2& DSW1(考试时可能有bug,C1、C2可以互相ping通)。剩下3道,在ASW1上,sh int f1/0/1,找到 FastEthernet1/0/1 is down, line protocol is down (errdisabled),
switchport port-security mac-address 0000.0000.0001, 并且show run,看到有“port-security”,确认为port security错误。
(1)ASW1, (2)Port Security, (3)In Configuration mode, using the interface range Fa 1/0/1 -2, then no switchport-security,followed by shutdown,no shutdown interface configuration commands. 解释:ASW1上的端口安全策略限制了C1和C2连接ASW1的端口通信(触发安全策略后处于error-disable状态)。 To allow Client1 to access the network, we must remove the port security configuration command that is allowing only the device with a MAC address of 0000.0000.0001. Since this port will still be in an errdisable state after this, we must also issue a shutdown/no shutdown to enable the port. 3、 Access Vlan:(Q38-40)在2层拓扑图中。 现象:C1和C2获得169.x.x.x.地址,互相可以ping通,但是ping不通DSW1&FTP。 其余2道, ASW1上sh vlan brief和sh run,看int f1/0/1 和2的端口,有没有划分到vlan里。有一个是没有划分vlan的,全部vlan都还在vlan1里,确认是Access Vlan的错误。
(1)ASW1, (2)Access vlans, (3)In Configuration mode, using the interface range Fastethernet 1/0/1-2, then switchport access vlan 10 command. 解释:The "switchport access vlan 10" change on the ports connecting the clients will correctly add both clients to the correct VLAN and move them from VLAN 1 to VLAN 10. 4、 Trunk/ Sw2Sw Connectivity:(Q41-43)在2层拓扑图中。 现象:C1和C2获得169.x.x.x.地址,互相可以ping通,但是ping不通DSW1&FTP。 ASW1上sh run,看到int port-channel 13和23的端口,不是switchport trunk allowed vlan 10,200(比如是20,200),确认是vlan trunk的错误。
(1)ASW1, (2)Switch to Switch Connectivity, (3)In Configuration mode, using the interface port-channel 13, port-channel 23, then configure switchport trunk allowed vlan none followed by switport trunk allowed vlan 10,200 commands.