Local Area Network (LAN) and VLAN Concepts

Overview of LAN

• Definition: A Local Area Network (LAN) is a group of devices within the same broadcast domain.
• Example: Devices connected to the same switch share the same broadcast domain.
• Diagram:
  • Red Network: Connected to Red Switch, same broadcast domain.
  • Blue Network: Connected to Blue Switch, separate broadcast domain.

Challenges with Separate Switches

• Separate Power Sources: Each switch requires its own power source.
• Space and Management: Requires more space and individual management.
• Solution: Use a single switch with VLANs to manage separate networks efficiently.

Virtual Local Area Networks (VLANs)

• Functionality: Allows separation within the same switch by creating different VLANs.
• Configuration:
  • Assign interfaces to specific VLANs (e.g., VLAN 1, VLAN 2, VLAN 3).
  • Only devices in the same VLAN can communicate.
• Benefits: Reduces hardware requirements and simplifies management.

VLAN Trunking

• Challenge: Connecting VLANs across multiple switches.
• Solution: Use VLAN trunking (802.1Q trunk).
  • Single Ethernet connection instead of multiple cables.
  • Tags each frame with VLAN information to ensure proper delivery.
• Tagging: Inserts a VLAN tag into Ethernet frames to distinguish traffic.

Native VLAN

• Default VLAN: Initially, all ports are part of a default VLAN, often VLAN 1.
• Native VLAN: Traffic traverses without tagging, used for specific management tasks.
• Configuration: Must match native VLANs across connected switches to avoid errors.

Layer 2 vs. Layer 3 Switching

• Layer 2 Switch: Operates at the Data Link layer (based on MAC addresses).
• Layer 3 Switch: Combines Layer 2 functionality with Layer 3 routing (based on IP addresses).
  • SVI (Switched Virtual Interfaces): Configured for routing between VLANs.
• Advantages: Saves space and power, easier administration.
• Limitations: Less capable routing compared to dedicated routers.

Voice and Data VLANs

• Voice over IP (VoIP): Combines voice and data over a single Ethernet connection.
• Challenge: Balancing bursty data traffic with consistent voice traffic.
• Solution: Separate voice and data into different VLANs using trunking.
  • Assign VLAN 200 for voice and VLAN 100 for data.
  • Requires compatible switch equipment to manage both phone and computer connections.

Conclusion

• VLANs: Efficiently manage network separation and connectivity using VLANs and trunking.
• Layer 3 Switching: Combines routing and switching in one device, beneficial for smaller networks.
• VoIP Integration: Simplifies network by running voice and data over the same infrastructure.