BGP Route Processing Steps

Question 1

Steps 1, 2, 3

Answer 1

• Step 1
  
  • Store the route in the Adj-RIB-In table
  • Apply inbound route policy based on the neighbor from which the route was received.
• Step 2
  
  • Update the Loc-RIB with the latest entry.
  • Adj-RIB-In table cleared to save memory.
• Step 3
  
  • Pass a validity check
    
    • route is valid
    • next-hop address is resolvable in the global RIB.
  • If route fails, it remains in the Loc-RIB table but is not processed further.

Question 2

Step 4

Answer 2

• Identify the BGP best path and pass only the best path and its path attributes to step 5

Question 3

Step 4 and 5

Answer 3

• Step 4
  
  • Identify the BGP best path and pass only the best path and its path attributes to step 5
• Step 5
  
  • Install the best-path route into the global RIB, process the outbound route policy, store the non-discarded routes in the Adj-RIB-Out table, and advertise to BGP peers