300-320 · Question #276
What are three primary components in IS-IS fast convergence? (Choose three.)
The correct answer is A. event propagation E. updating RIB and FIB F. SPF calculation. IS-IS fast convergence is broken into three sequential phases, each of which must be optimized. First, event propagation (A): topology change events must be detected and flooded rapidly via LSPs to all routers. Second, SPF calculation (F): once the topology database is updated…
Question
What are three primary components in IS-IS fast convergence? (Choose three.)
Options
- Aevent propagation
- BLSP flooding
- Cfast hellos
- Dmatching MTUs
- Eupdating RIB and FIB
- FSPF calculation
How the community answered
(39 responses)- A72% (28)
- B8% (3)
- C5% (2)
- D15% (6)
Explanation
IS-IS fast convergence is broken into three sequential phases, each of which must be optimized. First, event propagation (A): topology change events must be detected and flooded rapidly via LSPs to all routers. Second, SPF calculation (F): once the topology database is updated, the Shortest Path First algorithm recalculates the best paths. Third, RIB and FIB update (E): the new routes must be installed into the Routing Information Base and then programmed into the Forwarding Information Base for actual packet forwarding. Fast hellos (C) help accelerate failure detection but are a tuning knob rather than one of the three primary convergence phases. LSP flooding (B) is part of event propagation, not a separate phase. MTU matching (D) is a link requirement for neighbor adjacency, not a convergence component.
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