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Designing and Deploying L2TPv3-Based Layer 2 VPNs

Layer 2 VPNs (L2VPN) can be used to provide site-to-site Layer 2 connectivity. As discussed in Chapter 1, "What Is a Virtual Private Network?" L2VPNs can be built using technologies and protocols such as the Layer Two Tunneling Protocol version 3 (L2TPv3, RFC3931) and Any Transport over MPLS (AToM) and can fall into three categories:

  • Virtual Private Wire Service (VPWS) This type of L2VPN provides point-to-point MAN or WAN transport for Layer 2 protocols and connections such as Ethernet, High-Level Data Link Control (HDLC), PPP, Frame Relay, and ATM.
  • Virtual Private LAN Service (VPLS) A VPLS provides multipoint Ethernet connectivity.
  • IP-only Private LAN Service (IPLS) This is a newer type of L2VPN, and it provides multipoint IP-only connectivity.

A common question asked about L2VPNs (including L2TPv3-based L2VPNs) is why they might be preferred over Layer 3 site-to-site VPNs and when their deployment might be suitable.

L2TPv3 pseudowire (emulated circuit)-based L2VPNs are typically deployed by service providers in order to consolidate legacy and newer IP network infrastructure and offer newer Ethernet-based WAN connectivity to their customers. Figure 2-1 illustrates an L2TPv3-based L2VPN. Figure 2-1 shows L2TPv3 sessions over an IP backbone network between service Provider Edge (PE) routers: London.PE, Birmingham.PE, and Amsterdam.PE. The L2TPv3 sessions in Figure 2-1 are transporting the following Layer 2 protocol connections:

  • An Ethernet connection between Customer Edge (CE) routers mjlnet.London.PE and mjlnet.Birmingham.CE
  • A Frame Relay connection between CE routers cisco.Birmingham.CE and cisco.Amsterdam.CE
  • A PPP connection between CE routers vectorit.London.CE and vectorit.Amsterdam.CE

Figure 2-1. L2TPv3-Based L2VPN


Part I: Understanding VPN Technology

What Is a Virtual Private Network?

Part II: Site-to-Site VPNs

Designing and Deploying L2TPv3-Based Layer 2 VPNs

Designing and Implementing AToM-Based Layer 2 VPNs

Designing MPLS Layer 3 Site-to-Site VPNs

Advanced MPLS Layer 3 VPN Deployment Considerations

Deploying Site-to-Site IPsec VPNs

Scaling and Optimizing IPsec VPNs

Part III: Remote Access VPNs

Designing and Implementing L2TPv2 and L2TPv3 Remote Access VPNs

Designing and Deploying IPsec Remote Access and Teleworker VPNs

Designing and Building SSL Remote Access VPNs (WebVPN)

Part IV: Appendixes

Designing and Building SSL Remote Access VPNs (WebVPN)

Appendix B. Answers to Review Questions

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Comparing, Designing, and Deploying VPHs
Comparing, Designing, and Deploying VPNs
ISBN: 1587051796
EAN: 2147483647
Year: 2007
Pages: 124
Authors: Mark Lewis
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