350-501 · Question #570
350-501 Question #570: Real Exam Question with Answer & Explanation
The correct answer is B: calculating and establishing TE tunnels in accordance with network constraints. OSPF-TE extensions are designed to carry detailed network topology and resource information within the OSPF protocol. This expanded information is then used by MPLS Traffic Engineering to calculate and establish tunnels that meet specific operational constraints.
Question
What is the purpose of OSPF-TE extensions to MPLS traffic engineering functionality?
Options
- Aadvertising the TE tunnel routes to the OSPF domain
- Bcalculating and establishing TE tunnels in accordance with network constraints
- Ccarrying OSPF routing information for TE tunnels
- Dcalculating fast reroute to provide a backup path for TE tunnels
Explanation
OSPF-TE extensions are designed to carry detailed network topology and resource information within the OSPF protocol. This expanded information is then used by MPLS Traffic Engineering to calculate and establish tunnels that meet specific operational constraints.
Approach. OSPF-TE extensions introduce new TLVs (Type-Length-Value fields) within OSPF LSAs to carry traffic engineering parameters, such as link bandwidth, reservable bandwidth, and administrative groups. This detailed information is then utilized by the MPLS TE head-end router or a Path Computation Element (PCE) to calculate optimal paths for TE tunnels that satisfy specific resource or policy constraints, enabling efficient and constrained-based path selection.
Common mistakes.
- A. OSPF-TE extensions advertise link state and resource information relevant to traffic engineering, not the TE tunnel routes themselves. The tunnels are typically established by a separate MPLS control plane mechanism based on the TE information.
- C. While OSPF carries routing information, OSPF-TE specifically adds traffic engineering information, not general OSPF routing information, for the purpose of path computation for TE tunnels.
- D. OSPF-TE provides the necessary topology and resource data for path computation, which can include information relevant to Fast Reroute (FRR). However, OSPF-TE itself doesn't directly calculate the FRR backup paths; that is typically handled by the MPLS TE control plane using the distributed information.
Concept tested. OSPF-TE purpose in MPLS TE
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