OSPF-2

Question 1

What are the different neighbor states in OSPF?

Answer 1

1. Down: No Hello packet has been received from a previous “Full” Neighbor.
2. Attempt: Used for a manually configured neighbor.
3. Init: Hello packet received from a new neighbor.
4. 2-Way: Identifies compatible neighbors (non-DR/BDR relationships may stop here).
5. Exstart/Exchange: Master/Slave relationship determined and DBDS exchanged.
6. Loading: The LSR/LSA/LSU exchanges.
7. Full: Full State.

Question 2

Explain different OSPF LSA Types?

Answer 2

• (Type1)Router LSA : Describes router’s own links in an area.
• (Type2) Network LSA: Generated by DR (Designated Router) in multi-access networks.
• (Type3) Summary LSA: Advertises inter-area routes (sent by ABRs).
• (Type4) Summary ASBR LSA: Provides a route to an ASBR (Autonomous System Boundary Router).
• (Type5) External LSA: Used for external routes (redistributed into OSPF).
• (Type 7) NSSA LSA: Used in Not-So-Stubby Areas (NSSA) instead of Type 5.

Question 3

Explain different OSPF Network types.

Answer 3

1. Broadcast
2. Non-Broadcast (NBMA)
3. Point-to-Point
4. Point-to-multipoint
5. Point-to-multipoint non-broadcast

Question 4

What are the benefits of doing route summarization?

Answer 4

1. Smaller routing table.
2. Summarizes pool of addresses into one prefix.
3. Lessens the load on router processor and memory resources.
4. Less number of update messages.
5. Less bandwidth.

Question 5

What is Route Redistribution?

Answer 5

Route redistribution is the process of taking routes learned via one routing protocol and injecting those routes into another routing protocol domain.