A Tier-3 Service Provider is evolving into a Tier-2 Service Provider due to the amount of Enterprise business it is receiving. The network engineers are re-evaluating their IP/MPLS design consideratio

Route Targets control VRF import and export policies - they determine which VPNs can exchange routes - but they do not make overlapping IP prefixes unique within the provider's BGP table.

In an MPLS Layer 3 VPN, each customer VRF is assigned a unique RD that is prepended to customer IP prefixes before they are advertised into the provider's MP-BGP VPNv4 address family. This 8-byte value creates a globally unique VPNv4 route even when two different customers advertise identical IP prefixes, preventing route collisions in the control plane. Without unique RDs per customer VRF, the provider's BGP table cannot distinguish overlapping customer addresses, leading to routing instability.

Assigning unique IP address space via NAT or firewalls would eliminate overlapping addresses at the edge, but the scenario requires the network to natively carry overlapping addresses within separate VPNs rather than avoiding them.

VRF IDs are locally significant labels on a PE router used to identify the forwarding table for a packet; they are not propagated in the BGP control plane and do not resolve overlapping prefix collisions in the provider's VPNv4 table.