Route Target (RT)is aBGP extended community attributeused inMPLS Layer 3 VPNs (L3VPNs)to control theimport and exportof VPN routes between differentVPN instances (VRFs).
Explanation of Correct Answers:
✅A. Each VPN instance is associated with one or more pairs of VPN Target attributes, used to control VPN routing information advertisement and reception between sites.
Each VRF (VPN Routing and Forwarding instance) has an associated RTthat determines which routes areimported and exportedbetween VPNs.
RTs enableinter-VPN communicationwhile maintaining separation between VPN customers.
✅B. Export Target and Import Target are independent of each other and support multiple values to implement flexible VPN routing information advertisement and reception control.
TheExport RTspecifies which routes should be advertised.
TheImport RTspecifies which routes should be accepted into a VRF.
These can beconfigured independentlyto control traffic flow between VPNs.
✅C. RTs are classified into two types: Export Target and Import Target.
Export Target: Defineswhich VPN routes are advertised.
Import Target: Defineswhich VPN routes are accepted.
A VPN instance can have multiple RTsto allow flexibility.
✅D. The RT value is advertised to neighbors through the BGP extended community attribute in Update messages.
RTs are carried in BGP UPDATE messagesas part of theBGP extended community attribute, enabling VPN route exchange between PEs.
Reference from Huawei HCIE-Datacom Documentation:
Huawei MPLS VPN Configuration Guide – Route Target (RT) Concepts
HCIE-Datacom Study Material – BGP Route Advertisement in MPLS VPNs
