What is MPLS Traffic Engineering (TE) and what is an LSP?

• A. MPLS TE uses a single default path; LSP stands for Local Shared Path
• B. MPLS TE uses constraints to route traffic along optimal LSPs to meet performance goals
• C. LSP stands for Local Switching Protocol
• D. MPLS TE does not involve path selection and LSPs are used only for control plane signaling

Answer: (B)

MPLS Traffic Engineering focuses on directing traffic through an MPLS network along explicit, resource-aware routes rather than letting it follow whatever path the basic routing protocol happens to pick. It uses constraints—such as required bandwidth, latency, and reliability—to compute paths that can meet performance goals, and then establishes Label Switched Paths that carry labeled packets along those chosen routes. An LSP is the actual forward path through the MPLS network built by signaling to reserve resources and carry traffic from ingress to egress. TE uses these constrained LSPs to balance load and avoid congestion, which is why the statement that MPLS TE uses constraints to route traffic along optimal LSPs to meet performance goals is the best description. The other options misstate what LSP stands for, or TE’s behavior (such as relying on a single default path, or LSPs being only for control-plane signaling).