How does an MPLS Layer 3 VPN distinguish overlapping customer IP address spaces?

MPLS Layer 3 VPNs use a Route Distinguisher (RD) to differentiate overlapping customer IP address spaces. The RD is a 64-bit value prepended to each customer IPv4 prefix, creating a unique 96-bit VPNv4 address. This ensures that even if two different customers use the same private IP subnet (e.g., 192.168.1.0/24), their routes are distinct within the MPLS backbone. Route Targets (RTs) are used for controlling the import and export of VPNv4 routes between different VPN Routing and Forwarding (VRF) instances, not for distinguishing overlapping addresses themselves. Address families define the type of network layer reachability information (e.g., IPv4, VPNv4) but don't inherently differentiate overlapping addresses. MP-BGP is the routing protocol used to distribute VPNv4 routes, but the RD is the specific mechanism that makes those routes unique.