VPN Connectivity Between Different Service Providers
As the popularity of the MPLS VPN solution has grown, so has the size and reach of the end-customers of the service. The greater the number of sites within a particular Enterprise, the greater the likelihood that certain geographic locations will attach to different service providers. This requires a different connectivity model than the base MPLS VPN architecture provides.
In this situation, transit traffic between customer sites must pass through more than one autonomous system and more than one MPLS VPN backbone. Consider Figure 6-12, which shows how the sites within the BankCorp VPN attach to their local carriers.
Figure 6-12. BankCorp Interprovider Topology
Figure 6-12 illustrates that ...