Your company implemented LFA in the network to help with fast convergence in case a failure occurs on the network. However, while the network is being tested to confirm that LFA is working properly, t

Question

Options

• Arecursion
• Bflooding of packets
• Cmicroloops
• Dinterface dampening

• A
  11% (3)
• B
  21% (6)
• C
  61% (17)
• D
  7% (2)

Explanation

LFA (Loop-Free Alternates), defined in RFC 5286, is an IP Fast Reroute (IPFRR) mechanism that pre-computes backup next-hops so that traffic can be immediately rerouted upon link or node failure without waiting for full IGP convergence. However, LFA does not prevent microloops. Microloops are temporary forwarding loops that arise during the convergence period because different routers in the network update their RIBs/FIBs at different times. For a brief window, Router A may forward a packet toward Router B, which has already updated its table and now forwards that same packet back toward Router A - creating a loop until the TTL field decrements to zero, producing the 'TTL expired in transit' ICMP message. The 'limited amount of time' described in the question is the definitive indicator of microloops, as they are transient and self-resolve once all routers converge. Recursion causes routing instability but not TTL expiry loops; flooding is a Layer 2 behavior; and interface dampening suppresses flapping interfaces, which is unrelated to TTL expiry.

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