Knowledge Base

Layer 2 Virtual Private Network (L3VPNs)

What is a VPN?

A Layer 2 VPN, also known as Layer 2 Tunnel or Virtual Private Wire Service (VPWS), is a type of Virtual Private Network (VPN) technology that operates on the Data Link Layer (Layer 2) of the OSI model. Unlike Layer 3 VPNs, which encapsulate data packets with an additional IP header, Layer 2 VPNs tunnel Ethernet frames across public networks as if they were directly connected on a private Layer 2 network.

How does Layer 2 VPN works?

  • Encapsulation: Data frames are encapsulated within a Layer 2 tunnel protocol, such as PPPoE, MPLS, or Frame Relay. This tunnel hides the internal network topology and protects the data from unauthorized access.
  • Tunneling: Encapsulated frames are transported across the public network, either directly between VPN endpoints or through intermediary VPN service provider (VPNSP) infrastructure.
  • Decapsulation: Upon reaching the destination endpoint, the tunnel protocol is removed, and the original Ethernet frames are delivered to the target network segment.

Benefits of Layer 2 VPN:

  • Transparency: Provides seamless Layer 2 connectivity, extending a local network across geographically dispersed locations.
  • Simplified network management: Maintains network configuration and protocols on individual LAN segments, eliminating the need for complex routing configurations at endpoints.
  • Performance: Offers low latency and high bandwidth due to minimal overhead with frame encapsulation.
  • Security: Encrypts data at the Layer 2 level, providing an extra layer of protection compared to Layer 3 encryption.
  • Flexibility: Compatible with various Layer 2 technologies and network devices.

Who uses Layer 2 VPN?

  • Businesses: Connecting geographically dispersed offices or remote workers to ensure transparent and secure network access.
  • Data centers: Providing Layer 2 connectivity between physical or virtual servers located in different data centers.
  • Service providers: Offering VPWS services to businesses and other organizations for secure and flexible inter-network connectivity.

What will you learn here?

  • Fundamentals: Grasp the core of Layer 2 VPNs, understanding their benefits, limitations, and comparison to Layer 3 solutions.
  • Configuration: Seamlessly set up Layer 2 VPNs on diverse platforms, exploring protocols like VPLS and GRE.
  • Advanced Features: Unlock the potential of VLAN trunking, multi-site networks, and QoS control within Layer 2 VPNs.
  • Troubleshooting: Diagnose and fix common Layer 2 VPN issues like broadcast storms, spanning tree issues, and frame fragmentation.
  • Best Practices: Optimize performance, ensure secure inter-VLAN communication, and choose the right topology for your needs.

We encourage you to explore the resources listed below for further learning and to leave any questions or comments you may have.


We hope this comprehensive explanation clarifies the concept of Layer 2 VPNs!