Panasonic NN46240-710 - Manual (Page 81)

3 BGP/MPLS IP VPN troubleshooting
Nortel Secure Router 8000 Series
_________ Troubleshooting - VPN
3.1 BGP/MPLS IP VPN overview
This section covers the following topics:
• Introduction to VPN
• Network topology
• Operation model
3.1.1 Introduction to VPN
A public network is a set of uncorrelated systems that can exchange information freely with
each other. A private network is owned and managed by a single organization, formed by a
group of devices that share information.
In a private network, different sites use a dedicated leased line to realize interconnection,
ensuring that the connection between sites is exclusive. A private network is used only by the
enterprise that deploys it.
Though a single VPN service model can simplify network operations, it cannot meet the
requirements of various customers. Customer requirements can di^er in such aspects such as:
security, number of sites, number of users, route complexity, key application, traffic model,
traffic volume, experience in network operation, and the willingness to outsource network
services. To address the requirements, service operators must offer a series of services,
including diversifying VPN service models.
The following multiple VPN service models exist:
Traditional VPN
Frame relay (Layer 2)
Asynchronous Transfer Mode (ATM) (Layer 2)
Customer premise equipment (CPE)-based VPN
Layer 2 Tunneling Protocol (L2TP) and Point-to-Point Tunneling Protocol (PPTP) (Layer
2)
IPsec (Layer 3)
VPN deployed by service providers
MPLS Layer 2 VPN (Layer 2)
BGP/MPLS IP VPN or RFC2547bis (Layer 3)
RFC2547bis defines a mechanism, which allows service providers to use their own IP
backbone to provide VPN services. This mechanism is called BGP/MPLS VPNs where BGP
transfers VPN routing information from one site to another and MPLS establishes a tunnel that
carries traffic from one provider edge (PE) to another on the backbone network.
3-2 Nortel Networks Inc. Issue 5.3 (30 March2009)