MPLS and Next-Generation Networks: Foundations for NGN and Enterprise Virtualization

MPLS-VPN architecture can be further extended to implement advanced services, such as CsC or Inter-AS. For example, VPN sites might be geographically dispersed, requiring connectivity to different MPLS VPN service providers. That is, the transit between VPN sites might pass through multiple providers' MPLS backbones implying an exchange of VPN routing information between providers and the provider backbones might or might not provide VPN service directly. Figures 3-15 and 3-16 summarize the Inter-AS service problem and available options.

In the next section, we examine traffic engineering implementations as a service building block for MPLS-based networks.