Which of the following describes BGP route processing on the Alcatel-Lucent 7750 SR?

Question

Options

• AIf no import policy is specified, all valid BGP routes are passed to the BGP route selection process.
• BIf no export policy is specified, all non-BGP routes are populated into RIB-Out.
• CIf no import policy is specified, all BGP routes are populated into the route table.
• DIf no import policy is specified, only valid BGP routes are populated into RIB-Out.

• A
  94% (16)
• D
  6% (1)

Explanation

Option A is correct because on the Alcatel-Lucent 7750 SR, the absence of an import policy means the router applies a default "accept all valid" behavior - routes that pass basic BGP validity checks (reachable next-hop, no AS loop, etc.) are forwarded to the BGP route selection process, where the best path is then chosen for the routing table.

B is wrong because the default export behavior does not push non-BGP routes into RIB-Out; on the 7750 SR, non-BGP routes require an explicit export policy to be advertised to BGP peers.

C is wrong on two points: it says "all" routes (omitting the critical "valid" qualifier), and routes don't go directly into the route table - they first pass through the BGP route selection process, with only the best path being installed.

D is wrong because it confuses import and export directions. RIB-Out is an outbound structure populated during the export phase. Import policy governs what enters the BGP selection process (the inbound/RIB-In side), not RIB-Out.

Memory tip: Think of the flow as a one-way pipeline - Import → Selection → Route Table → Export → RIB-Out. Import policy sits at the entrance, export policy at the exit. No import policy = open door for valid routes at the entrance; no export policy ≠ open door at the exit.

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