17.7.6 Lab – Troubleshoot Connectivity Issues Answers


Part 1 Objectives: Identify the Problem


Implementation of Network Changes


Verify Complete Functionality


Document Findings and Configuration Modifications


Context / Scenario

In this lab, your firm is encountering difficulties with its Local Area Network (LAN). You are tasked with diagnosing and resolving network faults. In Part 1, you will connect to LAN devices and utilise troubleshooting tools to discover network faults, construct a hypothesis of likely cause, and test that theory. In Part 2, you will develop a strategy for resolving and implementing a solution. In Part 3, you will confirm the restoration of all functioning. Part 4 allows you to record your troubleshooting results as well as the configuration modifications you make to the LAN devices.

Note: Cisco 4221 routers running Cisco IOS XE Release 16.9.4 are used in CCNA hands-on labs (universalk9 image). The lab switches are Cisco Catalyst 2960s running Cisco IOS Release 15.2(2). (lanbasek9 image). Other routers, switches, and versions of Cisco IOS may be used. Depending on the model and Cisco IOS version, the available commands and output may differ from what is shown in the labs. For the right interface IDs, see the Router Interface Summary Table at the conclusion of the lab.

Essential Resources

Two Routers (Cisco 4221 with Cisco IOS XE Release 16.9.4 universal image or comparable)

1 Switch (Cisco 2960 equipped with Cisco IOS Release 15.2(2) lanbasek9 image or equivalent)

1 PC (Windows with a terminal emulation application, such as Tera Term) (Windows with a terminal emulation program, such as Tera Term)

Console cables for configuring Cisco IOS equipment via their console ports using Ethernet cables, as seen in the topology

Configuration Problem Solving

The following configurations must be applied to the devices shown in the topology. Before beginning the lab, copy and paste the settings onto the designated devices.

Lab Preconfiguration

The following configurations must be applied to the devices shown in the topology. These settings include the faults being introduced into the laboratory. Before beginning the lab, copy and paste the settings onto the designated devices.


PC:


Identifier: 192.168.1.10


Subnet Mask: 255.255.255.0


Default Router: (leave blank)


Answers: You have the option to change the PC's settings; if you do not, the student will recognise that the missing default gateway setting is an issue.

S1:


no ip domain-lookup


hostname S1


ip domain-name ccna-lab.com


username admin01 privilege 15 secret cisco12345


interface FastEthernet0/1


 shutdown


interface FastEthernet0/2


 shutdown


interface FastEthernet0/3


 shutdown


interface FastEthernet0/4


 shutdown


interface FastEthernet0/5


 speed 10


 duplex half


! duplex full


interface Vlan1


 ip address 192.168.1.2 255.255.255.0


ip default-gateway 192.168.1.0


!ip default-gateway 192.168.1.1



banner motd $ Authorized Users Only! $


line vty 0 4


 login local


 transport input ssh


line vty 5 15


 login local


 transport input ssh


crypto key generate rsa general-keys modulus 1024


end


R1:


hostname R1


no ip domain lookup


ip domain name ccna-lab.com


username admin01 privilege 15 secret cisco12345


interface GigabitEthernet0/0/1


 ip address 192.168.1.1 255.255.255.0


 no negotiation auto


 speed 100


! speed 100


! negotiation auto


 no shutdown



interface GigabitEthernet0/0/0


 ip address 10.1.1.1 255.255.255.252


 no shutdown


banner motd $ Authorized Users Only! $


line vty 0 4


 login local


!ip route 0.0.0.0 0.0.0.0 10.1.1.2


 transport input ssh


crypto key generate rsa general-keys modulus 1024


end


ISP:


hostname ISP


no ip domain lookup


interface GigabitEthernet0/0/0


 ip address 10.1.1.2 255.255.255.252


 no shut


interface Lo0


 ip address 209.165.200.226 255.255.255.255


ip route 0.0.0.0 0.0.0.0 10.1.1.1


end


First, identify the issue.

The only information available on the network issue is that customers are experiencing delayed response times and are unable to connect to an external device on the internet with the IP address 209.165.200.226. You must use network commands and tools on the LAN equipment shown in the topology to establish the likely cause(s) of these network difficulties.

Note: The login credentials admin01 and cisco12345 are needed to access the network equipment.


Troubleshoot the network in Step 1.

Utilize the various network troubleshooting tools while keeping in mind the need to restore the connection to the external server and remove poor response times.

Note: When connecting to network devices through SSH, execute the terminal monitor privileged exec command to enable log output on the SSH console.


Step two is to record the potential causes.

Mention the likely reasons for the network issues being experienced by workers.


Enter your response here.


The computer's default gateway is not set.


2. S1 Interface F0/5 is configured for half duplex with a speed of 10.


3. Set S1's default gateway to 192.168.1.0


3. The speed of R1 G0/0/1 is set to 100, and automatic negotiation is deactivated.


The Gateway of last resort is not configured for R1.


Implementation of Network Changes

You have informed your supervisor about the issues observed in Part 1. She has authorised these modifications and asked you to apply them.


Verify Complete Functionality

Confirm that all functionality has been fully restored. PC-A, S1, and R1 should be able to communicate with the external server, and ping responses from PC-A to the external server should not vary significantly in response time.


Document Findings and Configuration Modifications

Use the area given here to record the problems discovered during troubleshooting and the configuration modifications required to address them. Documentation may vary but should contain the date that troubleshooting was performed, the devices that were tested, the commands used and the output produced by those commands, the problems discovered, and the configuration modifications taken to fix those issues.


Reflection Question

This lab required you to troubleshoot all devices prior to making any modifications. Exists an alternative use of the troubleshooting methodology?

Answers may vary. Another use of the troubleshooting process would be to complete all six stages on one device before going on to the next. e.g. After determining that the PC's default gateway was not configured, you would configure the PC's default gateway and check operation. If network problems persist, you would next go to the next device, S1 in our example, if necessary. After completing the troubleshooting procedure on S1 and determining that problems still exist, you would go to R1. This procedure would continue until the network was fully operating.


Note: If you want to know how the router is set up, look at the interfaces to determine the kind of router it is and the number of interfaces it has. It is impossible to adequately list all of the possible configuration possibilities for each router class since there is no method to do so. Identifiers for the many potential configurations of Ethernet and Serial interfaces that may be found in the device are included in this table. The table does not include any additional kinds of interfaces, despite the fact that some routers have more than one kind of interface. An ISDN BRI interface is a good illustration of this kind of thing. The text included in parentheses denotes the permissible shorthand that may be used to represent the interface when issuing instructions to Cisco IOS.


Device Configs – Final

Router R1

R1# show run


version 16.9


service timestamps debug datetime msec


service timestamps log datetime msec


platform qfp utilization monitor load 80


no platform punt-keepalive disable-kernel-core


!


hostname R1


!


boot-start-marker


boot-end-marker


!


no aaa new-model


!


no ip domain lookup


ip domain name ccna-lab.com


!


login on-success log


!


subscriber templating


!


multilink bundle-name authenticated


!


no license smart enable


diagnostic bootup level minimal


!


spanning-tree extend system-id


!


username admin01 privilege 15 secret 5 $1$/Iz6$7tWVeWuJQPAk5G2fySfl0/


!


redundancy


 mode none


!


interface GigabitEthernet0/0/0


 ip address 10.1.1.1 255.255.255.252


 negotiation auto


!


interface GigabitEthernet0/0/1


 ip address 192.168.1.1 255.255.255.0


 negotiation auto


!


ip forward-protocol nd


no ip http server


ip http secure-server


ip route 0.0.0.0 0.0.0.0 10.1.1.2


!


control-plane


!


banner motd $ Authorized Users Only! $


!


line con 0


 logging synchronous


 transport input none


 stopbits 1


line aux 0


 stopbits 1


line vty 0 4


 login local


 transport input ssh


!


end


Switch S1

S1# show run


Building configuration…


Current configuration : 1585 bytes


!


version 15.2


service timestamps debug datetime msec


service timestamps log datetime msec


no service password-encryption


!


hostname S1


!


boot-start-marker


boot-end-marker


!


username admin01 privilege 15 secret 5 $1$y6iJ$uy3VBz1/JYXksFH99dKGa1


no aaa new-model


system mtu routing 1500


!


no ip domain-lookup


ip domain-name ccna-lab.com


spanning-tree mode pvst


spanning-tree extend system-id


vlan internal allocation policy ascending


!


interface FastEthernet0/1


 shutdown


!


interface FastEthernet0/2


 shutdown


!


interface FastEthernet0/3


 shutdown


!


interface FastEthernet0/4


 shutdown


!


interface FastEthernet0/5


 duplex full


!


interface FastEthernet0/6


!


interface FastEthernet0/7


!


interface FastEthernet0/8


!


interface FastEthernet0/9


!


interface FastEthernet0/10


!


interface FastEthernet0/11


!


interface FastEthernet0/12


!


interface FastEthernet0/13


!


interface FastEthernet0/14


!


interface FastEthernet0/15


!


interface FastEthernet0/16


!


interface FastEthernet0/17


!


interface FastEthernet0/18


!


interface FastEthernet0/19


!


interface FastEthernet0/20


!


interface FastEthernet0/21


!


interface FastEthernet0/22


!


interface FastEthernet0/23


!


interface FastEthernet0/24


!


interface GigabitEthernet0/1


!


interface GigabitEthernet0/2


!


interface Vlan1


 ip address 192.168.1.2 255.255.255.0


 shutdown


!


ip default-gateway 192.168.1.1


ip http server


ip http secure-server


!


banner motd $ Authorized Users Only! $


!


line con 0


 logging synchronous


line vty 0 4


 login local


 transport input ssh


line vty 5 15


 login local


 transport input ssh


!


end


Router ISP

ISP# show run


version 16.9


service timestamps debug datetime msec


service timestamps log datetime msec


platform qfp utilization monitor load 80


no platform punt-keepalive disable-kernel-core


!


hostname ISP


!


boot-start-marker


boot-end-marker


no aaa new-model


!


no ip domain lookup


login on-success log


!


subscriber templating


!


multilink bundle-name authenticated


!


spanning-tree extend system-id


!


redundancy


 mode none


!


nterface Loopback0


 ip address 209.165.200.226 255.255.255.255


!


interface GigabitEthernet0/0/0


 ip address 10.1.1.2 255.255.255.252


 negotiation auto


!


ip forward-protocol nd


no ip http server


ip http secure-server


ip route 0.0.0.0 0.0.0.0 10.1.1.1


!


control-plane


!


line con 0


 logging synchronous


 transport input none


 stopbits 1


line aux 0


 stopbits 1


line vty 0 4


 login local


end

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