Jeremy's IT Lab: CCNA Course - VLANs

Introduction

• Free, complete CCNA course.
• Encouragement to subscribe, like, comment, and share.
• Today's topic: VLANs (Virtual Local Area Networks).
• Important for CCNA exam and network engineering.

Lecture Outline

1. What is a LAN?
2. Broadcast Domains
3. Introduction to VLANs
4. Basics of VLAN Configuration on Cisco Switches

LANs and Broadcast Domains

• LAN (Local Area Network): Group of devices in a single location (e.g., home, office).
• Broadcast Domain: Group of devices that receive a broadcast frame (destination MAC of all Fs) sent by any member.
• Example network shows four broadcast domains:
  • PC1, PC2, SW1, and one interface of R1.
  • PC3, PC4, PC5, SW2, and one interface of R1.
  • PC6, PC7, PC8, SW3, and one interface of R2.
  • R1 and R2 connection.

Issues with Single LAN

• Security and Performance:
  • Unnecessary broadcast traffic affects performance.
  • Direct PC-to-PC traffic bypasses router security policies.
• To improve, separate departments into different subnets (e.g., Engineering, HR, Sales).

Introduction to VLANs

• VLANs (Virtual LANs): Logically separate devices at Layer 2 to create multiple broadcast domains within a single switch.
• VLANs allow applying security policies and reducing broadcast traffic.
• Example VLANs:
  • VLAN10 for Engineering
  • VLAN20 for HR
  • VLAN30 for Sales
• VLANs are configured on switches per interface.

VLAN Configuration on Cisco Switches

• Access Ports: Configured to be in a single VLAN, typically connecting to end hosts.
• Trunk Ports: Carry multiple VLANs (covered in next video).
• Default VLANs: VLAN1 (Default) and VLANs 1002-1005 (FDDI, Token Ring).
  • Exist by default and cannot be deleted.

Configuring VLANs

1. Use interface range command to select multiple interfaces.
2. Use switchport mode access to set interface as access port.
3. Use switchport access vlan [VLAN_ID] to assign VLAN.

• VLAN is created automatically if it doesn't exist.

4. Rename VLANs for clarity (e.g., VLAN 10 as "Engineering").
5. Verify VLANs using show vlan brief.

Quiz Summary

1. Broadcast Domains:
   • Without VLANs: 6 domains.
   • With configured VLANs: 5 domains.
2. VLAN Creation:
   • Switch creates VLAN if assigned to a non-existent VLAN.
3. Broadcast Traffic:
   • Limited to devices within the same VLAN.
4. VLAN Count on Switch:
   • Default and created VLANs total to 8.

Conclusion

• VLANs improve network security and performance by separating broadcast domains.
• Access ports facilitate VLAN configuration; trunk ports are for multiple VLANs.
• More details on VLANs in next video.
• Encouragement to use supplementary materials and practice labs.
• Acknowledgment of channel supporters and encouragement to engage with content.