Figure 70: Typical VPN Topology
All types of VPNs share certain components. Figure 70 shows a typical VPN topology.
Figure 70: Typical VPN Topology
The provider edge (PE) routers in the provider's network connect to the customer edge (CE) devices located at customer sites. PE routers support VPN and MPLS label functionality. Within a single VPN, pairs of PE routers are connected through a virtual tunnel, typically an LSP.
Provider routers within the core of the provider's network are not connected to any routers at a customer site but are part of the tunnel between pairs of PE routers. Provider routers support LSP functionality as part of the tunnel support, but do not support VPN functionality.
Customer edge (CE) devices are the routers or switches located at the customer site that connect to the provider's network. CE devices are typically IP routers, but they can also be Asynchronous Transfer Mode (ATM), Frame Relay, or Ethernet switches.
All VPN functions are performed by the PE routers. Neither CE devices nor provider routers are required to perform any VPN functions.