What happens to a route that is rejected by an import policy on an Alcatel-Lucent 7750 SR?

Question

Options

• AThe route is discarded.
• BThe route is kept in the RIB-In, but marked as an invalid route.
• CThe route is moved to the LOC-RIB, but not marked as a used route.
• DThe route is moved to the route table, but not to the FIB.

• A
  3% (1)
• B
  84% (26)
• C
  6% (2)
• D
  6% (2)

Explanation

On the Alcatel-Lucent 7750 SR, when an import policy rejects a route, the route is retained in the RIB-In but flagged as invalid - it is not used for path selection or installed anywhere further in the routing pipeline. This is a deliberate design: the router keeps a record of what was received from the peer without acting on it, which aids in troubleshooting and policy auditing without affecting the active routing table.

Why the distractors are wrong:

• A - The route is not discarded; it remains in the RIB-In so operators can inspect what was advertised by the peer.
• C - The LOC-RIB (local RIB) holds routes that have been accepted by policy and are candidates for best-path selection; a rejected route never reaches it.
• D - The route table and FIB are downstream of policy processing; a route must first pass the import policy before it can ever reach those structures.

Memory tip: Think of the RIB-In as the router's inbox - every received route lands there first. An import policy acts like a spam filter: rejected mail stays in the inbox marked "invalid," it just never gets moved to your active folder (LOC-RIB → route table → FIB).

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