L2VPN key concepts

Now that an overview of Ethernet-based L2VPNs has been provided, it is beneficial to review L2VPN concepts more closely. Virtual circuits, pseudowires, and virtual switches will be explored in some detail below.

Virtual Circuits/Pseudowires

The most fundamental component within an L2VPN is called a virtual circuit (VC) or pseudowire (PW). These terms are often used interchangeably. A VC defines a secure, logical connection between two or more customer endpoints. VCs may be encapsulated using Ethernet Q-in-Q, IEEE 802.1ad, or MPLS Martini.

Service providers differentiate service offerings by making available robust, guaranteed services. World Wide Packets’ unique traffic parameters enable service providers to create VCs that provide any combination of guaranteed, rate-limited, or best-effort bandwidth profiles. This flexibility permits service providers to realize increased revenue generation and to accelerate return on investment by enabling multiple tiered services over a unified infrastructure.

Virtual Switches

Both CE and PE devices that are L2VPN-aware logically segment their internal switch/forwarding functions into multiple Virtual Switches (VS). Consider the left-most PE Bridge in the preceding figure. Since it connects to two separate customers, the PE Bridge must contain the forwarding, flooding, broadcast, and multicast traffic appropriately. This is accomplished using two VSs, one for Customer A, and one for Customer B.

Continue

• Part 1:
  Introduction
• Part 2:
  Ethernet-based L2VPNs
• Part 3:
  L2VPN key Key Concepts
• Part 4:
  MPLS-based L2VPNs
• Part 5:
  VPN Standards Development
• Part 6:
  Layer 2 Control Frame Transport
• Part 7:
  L2VPN QoS and Management
• Part 8:
  Conclusion