350-501 · Question #71
350-501 Question #71: Real Exam Question with Answer & Explanation
The correct answer is C: Use BGP LS to distribute information across the domains.. To distribute network topology and traffic engineering information from multiple IGP domains (IS-IS and OSPFv2) to a centralized offline path calculation system for MPLS TE, BGP Link-State (BGP LS) is the appropriate method. BGP LS is specifically designed to collect and export l
Question
A service provider network is currently divided into five IGP domains; four IS-IS domains and one OSPFv2 domain. Because of customer demand, it has been decided to implement Cisco MPLS TE tunnels using a centralized offline path calculation system. Which method provides a way to distribute the required information to the path calculation system?
Options
- AConvert the OSPFv2 domain to a new IS-IS instance.
- BUse RSVP-TE IS-IS/OSPFv2 extensions to distribute the information.
- CUse BGP LS to distribute information across the domains.
- DPerform mutual redistribution between all IGP domains.
Explanation
To distribute network topology and traffic engineering information from multiple IGP domains (IS-IS and OSPFv2) to a centralized offline path calculation system for MPLS TE, BGP Link-State (BGP LS) is the appropriate method. BGP LS is specifically designed to collect and export link-state and TE attributes from various IGP domains to external controllers.
Common mistakes.
- A. Converting the OSPFv2 domain to IS-IS would simplify the number of IGP types but would still result in multiple IGP domains, each with its own link-state database, and would not solve the problem of distributing this consolidated information to a centralized system.
- B. RSVP-TE extensions are used by IGPs to flood TE attributes within a single IGP domain, and RSVP-TE itself is a signaling protocol for tunnel setup, not a mechanism to export a consolidated view of multiple domains' TE information to an external system.
- D. Mutual redistribution between IGP domains would allow routes to be exchanged, but it primarily deals with reachability information and does not propagate the detailed link-state and traffic engineering attributes necessary for a centralized system to perform constrained path calculations for MPLS TE tunnels.
Concept tested. BGP Link-State for multi-domain TE
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