Layer 2 Vpn Architectures [Electronic resources] نسخه متنی

Introduction

Until recently, the VPN landscape has been quite complex as service providers have struggled with how best to accommodate traditional access technologies (such as, dial, Frame Relay, and ATM) along with new ones (like, Ethernet and wireless) and Layer 3 VPNs over a common network infrastructure. A new solution, enabling service providers to converge Layer 2 and Layer 3 services and provide legacy data services over an IP or MPLS backbone, promises to simplify matters, benefiting both service providers and enterprises.

The historical disconnect between legacy Layer 2 and Layer 3 VPN solutions has forced service providers to build, operate, and maintain separate infrastructures to accommodate various VPN access technologies. However, this costly proposition is no longer necessary. As part of its new Unified VPN Suite, Cisco Systems now offers next-generation Layer 2 VPN services like Layer 2 Tunneling Protocol version 3 (L2TPv3) and Any Transport over MPLS (AToM) that enable service providers to offer Frame Relay, ATM, Ethernet, and leased line services over a common IP/MPLS core network. By unifying multiple network layers and providing an integrated set of software services and management tools over this infrastructure, the Cisco Layer 2 VPN solution enables established carriers, IP-oriented ISP/CLECs, and large-enterprise customers (LECs) to reach a broader set of potential VPN customers and offer truly global VPNs.

Although Layer 3 MPLS VPNs fulfill the market need for some customers, they have some drawbacks. Namely, Layer 3 MPLS VPNs only handle IP traffic, and they require the customer to change their usual CPE/subscriber model from a Layer 2 peering model to interfacing with the service provider at Layer 3. Ideally, carriers with existing legacy Layer 2 and Layer 3 networks would like to move towards a single backbone while new carriers would like to sell the lucrative Layer 2 services over their existing Layer 3 cores.

The solution in these cases is a technology that allows Layer 2 transport over a Layer 3 infrastructure. This book assists readers looking to meet those requirements by explaining the history and implementation details of the two technologies available from the Cisco Unified VPN suite: AToM for MPLS-based cores and L2TPv3 for native IP cores.