350-501 Question #194: Real Exam Question with Answer & Explanation

Question

A network engineer is tasked with supporting traffic discrimination over MPLS traffic engineering tunnels. To allocate restricted bandwidth to a certain type of traffic with no QoS degradation, which technique must be used?

Options

• Aintegrated services
• BMPLS TE Diff-Serv full allocation model
• CMPLS TE Diff-Serv Russian doll model
• DIP precedence
• Eclass of service

Explanation

To achieve traffic discrimination and guaranteed QoS with restricted bandwidth allocation over MPLS TE tunnels, the MPLS TE Diff-Serv Russian Doll model is the appropriate technique.

Common mistakes.

• A. Integrated Services (IntServ) is a resource reservation model (RSVP) which is typically not scalable for large-scale DiffServ traffic discrimination across an MPLS TE backbone.
• B. The MPLS TE Diff-Serv full allocation model uses separate tunnels for each class, which can lead to inefficient bandwidth utilization due to static, unshared reservations, potentially not optimizing restricted bandwidth use.
• D. IP Precedence is a basic IP QoS marking mechanism and does not provide the sophisticated bandwidth allocation and traffic engineering capabilities required for this scenario.
• E. Class of Service (CoS) is a general QoS concept and not a specific technique for allocating restricted bandwidth and preventing QoS degradation within MPLS TE tunnels.

Concept tested. MPLS TE DiffServ models (Russian Doll)

Reference. https://www.cisco.com/c/en/us/td/docs/ios/mpls/configuration/guide/12_4t/mp_12_4t_book/mp_te_diff_serv.html

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