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.
1## 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).
2## 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.
3## 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