RD and RT are introduced to BGP/MPLS IP VPN networks.

In BGP/MPLS IP VPN networks:

✅ A. True – The Route Distinguisher (RD) is used to differentiate overlapping IPv4 addresses in different VPNs. It is prepended to the IPv4 address to create a VPNv4 address.

✅ C. True – A VPNv4 address is 96 bits long:

64-bit RD

32-bit IPv4 address

❌ B is false – The RT (Route Target) does determine which VPN instance a route belongs to. So B is an incorrect statement.

❌ D is false – A route can have multiple RTs, allowing flexible import/export control.

✅ Official Reference from Huawei:

" A VPNv4 address consists of a 64-bit RD and a 32-bit IPv4 address. The RD makes addresses globally unique. RTs are extended BGP communities used for route import/export. A VPNv4 route may carry multiple RTs. "

— [Huawei HCIA-Datacom Guide – MPLS VPN Chapter]