How are customer routes isolated on PE routers in an MPLS Layer 3 VPN?

VRFs (Virtual Routing and Forwarding) are used on PE routers to maintain separate routing and forwarding tables for each customer VPN. This allows for complete isolation of customer routes and prevents routing information from one customer from mixing with another, even if they use overlapping IP address spaces. Each VRF is associated with one or more customer interfaces and has its own routing protocol instances and forwarding table.

VRGs (Virtual Routing Groups) is not a standard or recognized technology for isolating customer routes in MPLS Layer 3 VPNs.

MP-BGP (Multi-Protocol BGP) is used to exchange VPNv4 or VPNv6 routes between PE routers across the MPLS backbone, but it relies on VRFs on the PE routers to initially distinguish and import customer routes.

LDP (Label Distribution Protocol) is used to distribute labels for the forwarding equivalence classes (FECs) of the MPLS core, primarily for transporting labeled packets between P and PE routers, not for customer route isolation.