Master Troubleshooting Cisco Switch Trunk Issues

Table of Contents

1. Introduction
2. The Issue with Accessing the New Accounts Server
3. Troubleshooting the Issue
4. Checking the IP Configuration of the Server
5. Verifying Connectivity between Switches
6. Checking VLAN Configuration on Switches
7. Configuring Trunk Ports
8. Allowing VLANs on Trunk Ports
9. Configuring Correct VLANs for Communication
10. Conclusion

Introduction

In this article, we will discuss a troubleshooting ticket related to accessing a new accounts server. We will analyze the issue faced by a user named Rahul from the accounts department, who is able to access the old accounts server but not the new one. We will go step-by-step to troubleshoot the problem and find a solution.

The Issue with Accessing the New Accounts Server

Rahul, from the accounts department, is encountering difficulty in accessing the new accounts server (10.1.1.100), even though he can access the old accounts server (10.1.101). This issue is preventing him from performing his tasks effectively. Our goal is to identify the cause of this problem and provide a suitable solution.

Troubleshooting the Issue

To begin troubleshooting, we first need to check the IP configuration of the new accounts server. This step is important because misconfigured IP addresses can often cause connectivity issues. By verifying the IP settings, we can determine if there are any errors in the configuration.

Checking the IP Configuration of the Server

Upon examining the IP address configuration of the new accounts server, we discover that there is an error in the IP address assignment. The server is currently configured with an incorrect IP address (10.1.10), instead of the correct IP address (10.1.100). To rectify this issue, we need to modify the IP address to the correct value.

Verifying Connectivity between Switches

Despite correcting the IP address configuration on the server, Rahul is still unable to ping the new accounts server. To identify the cause of this problem, we need to check the communication between the switches associated with the old and new servers. This step is essential because a lack of connectivity between switches can hinder communication between devices.

Checking VLAN Configuration on Switches

Upon further investigation, we observe that both Rahul's PC and the new accounts server are connected to the same switch. However, the new accounts server is connected to a different switch port. Both devices belong to the same VLAN (VLAN 100), but the communication between them is still not established. We need to verify the VLAN configuration on both switches to ensure they are correctly configured.

Configuring Trunk Ports

Upon checking the VLAN configuration, we discover that the connectivity between the switches is established through a trunk port. Trunk ports are responsible for carrying traffic for multiple VLANs. We need to confirm that the trunk ports are correctly configured and operational on both switches. This step is crucial because if the trunk ports are not set up properly, it can lead to communication issues.

Allowing VLANs on Trunk Ports

A crucial aspect of trunk port configuration is ensuring that the appropriate VLANs are allowed on the trunk. By default, all VLANs are allowed on trunk ports. However, in this Scenario, the VLAN 100 is not included in the allowed VLAN list, causing the communication issue. We need to add VLAN 100 to the list of allowed VLANs on the trunk ports to resolve this problem.

Configuring Correct VLANs for Communication

After correcting the allowed VLANs on the trunk ports, we need to verify if the communication is established between Rahul's PC and the new accounts server. If the VLAN configuration is properly set up and the trunk ports allow the necessary VLANs, we should see successful communication between the two devices.

Conclusion

In conclusion, we have successfully troubleshooted the issue faced by Rahul in accessing the new accounts server. By identifying and rectifying errors in the IP configuration and VLAN settings, we have restored communication between Rahul's PC and the new accounts server. It is crucial to ensure correct IP configuration and proper VLAN configuration on trunk ports to avoid such issues in the future.