2.1.2 Lab - Observe STP Topology Changes and Implement RSTP (Packet Tracer)

Introduction

In this tutorial, you will learn how to observe Spanning Tree Protocol (STP) topology changes and implement Rapid Spanning Tree Protocol (RSTP) using Cisco Packet Tracer. Understanding these protocols is crucial for ensuring loop-free network topologies and improving network efficiency. This guide will walk you through the necessary steps to set up your network and observe the effects of topology changes.

Step 1: Set Up Your Network Topology

• Open Cisco Packet Tracer.
• Create a new project and add the following devices to your workspace:
  • 3 Switches (e.g., Switch1, Switch2, Switch3)
  • 1 Router (optional, for additional routing capabilities)
  • Devices (PCs or servers) to connect to each switch.
• Connect the switches using Ethernet cables:
  • Switch1 to Switch2
  • Switch2 to Switch3
  • Switch3 back to Switch1 to form a triangle topology.

Step 2: Configure Basic Switch Settings

• Click on each switch and enter the CLI (Command Line Interface).
• Set the hostname for each switch:

  Switch> enable
  Switch# configure terminal
  Switch(config)# hostname Switch1
  

• Repeat for Switch2 and Switch3.
• Ensure that all switches have the same VLAN configurations:
  • Create VLAN 10 on each switch:

  Switch(config)# vlan 10
  Switch(config-vlan)# name VLAN10
  

Step 3: Enable STP on All Switches

• In the CLI of each switch, ensure that STP is enabled (it is by default):

  Switch(config)# spanning-tree vlan 10
  

Step 4: Observe STP Topology

• Use the command show spanning-tree on each switch to observe the STP topology:

  Switch# show spanning-tree
  

• Note the root bridge and the designated ports. Record this information for later comparison.

Step 5: Implement RSTP

• Transition from STP to RSTP on each switch:

  Switch(config)# spanning-tree mode rapid-pvst
  

• Verify the RSTP configuration with:

  Switch# show spanning-tree
  

• Observe how RSTP affects the port states and the overall topology.

Step 6: Simulate Topology Changes

• Disconnect one of the links between switches to simulate a topology change.
• Use the command show spanning-tree to observe the changes in port states as RSTP recalculates the topology.
• Reconnect the link and observe how quickly RSTP converges compared to traditional STP.

Step 7: Analyze the Results

• Compare the time taken for convergence between STP and RSTP.
• Document the differences in the port states and root bridge election.

Conclusion

In this tutorial, you have observed how to implement RSTP and how it responds to topology changes compared to traditional STP. Understanding these protocols will help you design more resilient networks. As a next step, consider experimenting with different network topologies and additional switches to further understand the dynamics of spanning tree protocols.