Technology Guide: Demystifying Layer 2 and Layer 3 VPNs
Table of Contents
This 54-page Technology Guide includes 5 Tables and 21 Figures.
| Section | Description | Page |
|---|---|---|
| Foreword | 6 | |
| 1 | Introduction | 7 |
| 2 | Understanding VPNs | 8 |
| 3 | Overview: Layer 2 and Layer 3 VPNs | 11 |
| 3.1 | Layer 2 VPNs | 11 |
| 3.1.1 | Layer 2 Virtual Circuits and Virtual Paths | 11 |
| 3.1.2 | Layer 2 Ethernet Services | 14 |
| 3.1.3 | Layer 2 Metro Ethernet Services | 15 |
| 3.1.4 | Layer 2 VPLS Services | 17 |
| 3.2 | Layer 3 VPNs | 18 |
| 3.2.1 | Internet-based IP VPNs | 19 |
| 3.2.2 | Private IP Networks | 19 |
| 3.3 | Impact of Architecture on Tariff Structures | 22 |
| 4 | Technology Comparisons | 25 |
| 4.1 | Overview | 25 |
| 4.2 | Technology Ratings | 25 |
| 4.2.1 | Fast Network Recovery | 27 |
| 4.2.2 | Scalability (Number of Sites) | 27 |
| 4.2.3 | Scalability (Bandwidth) | 28 |
| 4.2.4 | Native Mesh Topology | 28 |
| 4.2.5 | Support for Traffic Engineering | 29 |
| 4.2.6 | Deterministic QoS | 30 |
| 4.2.7 | Guaranteed Bandwidth | 30 |
| 4.2.8 | Customer Specification of QoS Parameters | 31 |
| 4.2.9 | Low Network Complexity | 31 |
| 4.2.10 | Customer Control of Layer 3 Routing and IP Addressing | 32 |
| 4.2.11 | National VLANs | 32 |
| 4.2.12 | Customer Control of VLAN Numbering Across the WAN | 33 |
| 4.2.13 | CE Router | 34 |
| 4.2.14 | Suitability for Small Sites | 34 |
| 4.2.15 | Support for Mixed Physical Layer Technologies (Layer 1); Support for Mixed Access Layer Technologies (Layer 2); and Native Support for Legacy Layer 3 Protocols | 35 |
| 4.2.16 | Internet-Borne Security Threats | 35 |
| 4.2.17 | Multi-Homing for WAN Redundancy | 36 |
| 4.3 | Business Features of Layer 2 and Layer 3 Services | 37 |
| 4.3.1 | Multi-point Any-to-Any Connectivity | 38 |
| 4.3.2 | National Coverage | 38 |
| 4.3.3 | Bandwidth Scalability | 39 |
| 4.3.4 | Real-Time Application Support (Enabled by Deterministic QoS) | 39 |
| 4.3.5 | Service Level Agreements Based on QoS Attributes | 40 |
| 4.3.6 | Private Carrier Network | 40 |
| 4.3.7 | Interception, Denial-of-Service (DOS) and Viral Attacks | 41 |
| 4.3.8 | Very High Speed Encryption Support | 41 |
| 4.3.9 | Single Connection for Enterprise and Internet Access | 42 |
| 4.3.10 | Connectivity Support for TDM PABXs | 42 |
| 4.3.11 | Connectivity and QoS Support for IP Telephony | 43 |
| 4.3.12 | Logical Segregation of Applications and/or Users via use of National VLANs; Flexibility to Change VLAN Numbering without Carrier Coordination | 43 |
| 4.3.13 | Flexibility to Change IP Addressing | 44 |
| 5 | Business Considerations Impacting the Selection of Layer 2 and Layer 3 Services | 45 |
| 5.1 | Introduction | 45 |
| 5.2 | Network Consolidation | 45 |
| 5.3 | Convergence | 49 |
| 5.4 | QoS and Site Connectivity | 51 |
| 5.5 | Legacy Network Support | 52 |
| 6 | Concluding Remarks | 53 |
This Technology Guide was made possible by the kind sponsorship of NextGen Networks.
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