After a redundant route processor failure occurs on a Layer 3 device, which mechanism allows for packets to be forwarded from a neighboring router based on the most recent tables?

Question

Options

• ARPVST+
• BNSF
• CBFD
• DRP failover

• A
  10% (2)
• B
  76% (16)
• C
  10% (2)
• D
  5% (1)

Explanation

NSF (Non-Stop Forwarding) Explained

NSF (Non-Stop Forwarding) is correct because it allows a router to continue forwarding packets using its existing Forwarding Information Base (FIB) and CEF tables even while the control plane is recovering from a Route Processor (RP) failure - neighboring routers with NSF-awareness assist by maintaining adjacency and sharing their most recent routing tables to restore the recovered RP's state seamlessly.

Why the distractors are wrong:

• RPVST+ (Rapid Per-VLAN Spanning Tree Plus) is a Layer 2 switching protocol that prevents loops in VLANs - it has nothing to do with Layer 3 route processor failover.
• BFD (Bidirectional Forwarding Detection) is a rapid link/path failure detection protocol, not a mechanism for maintaining packet forwarding during an RP failure.
• RP Failover describes the physical switchover event itself (switching from active to standby RP), but does not describe the mechanism that keeps packets flowing based on neighboring router tables - that role belongs to NSF.

Memory Tip: Think of NSF as "Never Stop Forwarding" - when the brain (RP) goes down, the router keeps its muscle memory (FIB) intact and asks its neighbors to help rebuild what was lost.

No community discussion yet for this question.