Free CCNA | VLANs (Part 2) | Day 17 | CCNA 200-301 Complete Course

Introduction

This tutorial covers the concepts of VLANs (Virtual Local Area Networks) as presented in Jeremy's IT Lab's CCNA 200-301 course. By understanding VLANs, trunk ports, native VLANs, and Router on a Stick (ROAS), you'll gain essential knowledge for managing network traffic and segmentation. This guide outlines the steps to configure VLANs effectively and highlights key concepts to enhance your CCNA preparation.

Step 1: Understand VLAN Basics

• Definition: A VLAN is a logical grouping of devices on a network, allowing them to communicate as if they were on the same physical network, regardless of their location.
• Benefits:
  • Improved security by segmenting traffic.
  • Reduced broadcast domains, leading to better performance.
  • Flexibility in network design.

Step 2: Review Network Topology

• Familiarize yourself with the network topology used in your environment.
• Identify key devices such as switches and routers that will be involved in VLAN configuration.

Step 3: Configure Trunk Ports

• Trunk Ports: These are ports configured to carry traffic for multiple VLANs.
• Configuration Steps:
  1. Access your switch’s configuration mode.
  2. Identify the port to be configured as a trunk.
  3. Use the following command to set the port as a trunk:

     switchport mode trunk
     

  4. Specify allowed VLANs if necessary.

Step 4: Learn VLAN Tagging

• VLAN Tagging: This process adds a tag to frames to identify the VLAN they belong to.
• Protocols:
  • ISL (Inter-Switch Link): Cisco proprietary.
  • 802.1Q: Industry standard.
• 802.1Q Tag Structure:
  • TPID: Tag Protocol Identifier.
  • PCI: Priority Code Point.
  • DEI: Drop Eligible Indicator.
  • VID: VLAN Identifier.

Step 5: Understand VLAN Ranges

• VLANs are categorized into different ranges:
  • Standard VLANs: 1-1005.
  • Extended VLANs: 1006-4095 (used in larger networks).

Step 6: Configure Native VLAN

• The native VLAN is the default VLAN for untagged traffic on a trunk port.
• To configure the native VLAN:
  1. Enter interface configuration mode.
  2. Use the command:

     switchport trunk native vlan [VLAN_ID]
     

Step 7: Configure Router on a Stick (ROAS)

• ROAS Concept: This method involves a single router interface handling multiple VLANs using sub-interfaces.
• Configuration Steps:
  1. Create sub-interfaces on the router for each VLAN:

     interface gig0/0.10
     encapsulation dot1Q 10
     ip address [IP_ADDRESS] [SUBNET_MASK]
     

  2. Repeat for each VLAN, changing the VLAN ID and IP address accordingly.

Step 8: Review and Test Your Configuration

• Verify your VLAN configurations using:

  show vlan brief
  show interfaces trunk
  

• Test connectivity between devices on the same VLAN and ensure isolation between different VLANs.

Conclusion

In this tutorial, you learned about VLANs, trunk ports, native VLAN configuration, and Router on a Stick. By mastering these concepts, you enhance your ability to design and manage efficient and secure networks. Next, consider practicing with Packet Tracer labs to reinforce your understanding and prepare for the CCNA exam.