Comprehensive and Detailed In-Depth Explanation:
This question is based on MPLS (Multiprotocol Label Switching) and its interaction with routing protocols. The goal is to ensure PC1 (10.1.1.1) can communicate with PC2 (10.3.3.1) over MPLS. Let's analyze each option carefully.
1️⃣ Understanding MPLS Routing Requirements
To forward traffic using MPLS and LDP, we need:
An IGP (Interior Gateway Protocol) like OSPF or IS-IS to advertise network reachability.
Loopback interfaces advertised in OSPF to establish LDP neighbor relationships.
Consistent MPLS LDP enablement on all links in the MPLS domain.
End-to-end IP reachability between loopbacks (since LDP uses the loopback for label distribution).
2️⃣ Option A (Correct Answer) Analysis
This configuration enables OSPF on all routers (R1, R2, and R3) across the MPLS domain:
✅ All networks are advertised in OSPF area 0, ensuring IP reachability.✅ Loopback interfaces (1.1.1.1, 2.2.2.2, 3.3.3.3) are included, which is required for MPLS LDP peer establishment.✅ PC1's network (10.1.1.0/24) and PC2's network (10.3.3.0/24) are properly advertised, ensuring end-to-end connectivity.✅ R1, R2, and R3 have OSPF neighbor relationships, meaning LDP can use OSPF routes for label switching.
???? Conclusion: Option A meets all MPLS forwarding requirements and is the correct answer.
3️⃣ Why Other Options Are Incorrect
???? Option B (Incorrect)
Uses BGP instead of OSPF, which is not optimal for MPLS forwarding in a simple MPLS domain.
LDP requires an IGP like OSPF or IS-IS to work efficiently.
BGP alone does not establish LDP label bindings between R1, R2, and R3.
???? Option C (Incorrect)
Mixes OSPF and BGP, causing routing inconsistency.
Uses ip ip-prefix and recursive lookup, which is unnecessary in a standard MPLS domain.
BGP does not distribute labels dynamically like an IGP with LDP.
???? Option D (Incorrect)
R1 does not advertise the 10.1.1.0/24 network, meaning PC1’s network is not reachable.
R3 does not advertise the 10.3.3.0/24 network, meaning PC2’s network is not reachable.
Missing essential routing entries for full end-to-end reachability.
References:
✅ HCIP-Datacom Advanced Routing & Switching Technology✅ Huawei Official MPLS and LDP Configuration Guide✅ Huawei Enterprise Networking Documentation
