MPLS VPN 技术.ppt

MPLS VPN Technology VPN Terminology VPN Terminology VPN Implementation Technologies VPN services can be offered based on two major paradigms: Overlay Virtual Private Networks where the Service Provider provides virtual point-to-point links between customer sites Peer-to-Peer Virtual Private Networks where the Service Provider participates in the customer routing Overlay VPN Implementation(Frame Relay Example) Layer-3 routing in Overlay VPN implementation Service Provider infrastructure appears as point-to-point links to customer routes Routing protocols run directly between customer routers Service Provider does not see customer routes and is responsible only for providing point-to-point transport of customer data Overlay VPNLayer-1 Implementation This is the traditional TDM solution: Service Provider establishes physical-layer connectivity between customer sites Customer takes responsibility for all higher layers Overlay VPNLayer-2 Implementation This is the traditional Switched WAN solution: Service Provider establishes layer-2 virtual circuits between customer sites Customer takes responsibility for all higher layers Overlay VPNIP Tunneling VPN is implemented with IP-over-IP tunnels Tunnels are established with GRE or IPSec GRE is simpler (and quicker), IPSec provides authentication and security Overlay VPNLayer-2 Forwarding VPN is implemented with PPP-over-IP tunnels Usually used in access environments (dial-up, DSL) Peer-to-Peer VPN Concept Peer-to-Peer VPN with Packet Filters MPLS VPN Architecture MPLS VPN combines the best features of overlay VPN and peer-to-peer VPN PE routers participate in customer routing, guaranteeing optimum routing between sites and easy provisioning PE routers carry a separate sets of routes for each customer (similar to dedicated PE router approach) Customers can use overlapping addresses MPLS VPN Terminology Routing Information Propagation Across P-Network Routing Information Propagation Across P-Network Routing Information P