13.6 Layer 3 VPNs


Service providers can implement VPN services for their customers over their existing IP infrastructures (see RFC 2547bis for details). In this implementation, the VPN is made up of a collection of different routers that includes the P and PE routers. These are the routers belonging to the provider that exchange routing information with each other using the service provider's existing infrastructure. These types of VPNs are known as BGP/MPLS VPNs because they use BGP to distribute the VPN routing information, while MPLS provides the forwarding mechanism for VPN traffic.

These types of VPNs are made up of customer equipment and provider equipment. The customer equipment is the router located at each customer's site, and the provider equipment is in the service provider's network. In this configuration, the provider's network will function as the glue to connect the customers' sites together. To keep one customer's traffic separate from another's, the provider will implement different types of policy that govern how traffic from different customers will be treated. Customers will have at least one VPN configured by the provider that will carry only their traffic. The service provider can support many VPNs, but must ensure that traffic from one VPN is not mixed with traffic from another. The customer connecting to the provider's network and using the VPN can choose to use either public addressing or private addressing as defined in RFC 1918.

The following sections describe BGP/MPLS VPN implementation based on RFC 2547bis. It explains how these VPNs operate and how the supporting protocols, like BGP and MPLS, play a role in today's VPN implementations .



Juniper Networks Reference Guide. JUNOS Routing, Configuration, and Architecture
Juniper Networks Reference Guide: JUNOS Routing, Configuration, and Architecture: JUNOS Routing, Configuration, and Architecture
ISBN: 0201775921
EAN: 2147483647
Year: 2002
Pages: 176

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