Table of Contents
- 1 What is Type 1 and Type 2 LSA?
- 2 What is a Type 5 LSA?
- 3 Why is LSA type 4 needed?
- 4 What defines the relationship between Type 5 and Type 7 LSAs?
- 5 What is LSA and Lsdb?
- 6 What is NSSA and totally NSSA?
- 7 What are the different types of LSA generated by the ABR?
- 8 What is the difference between Type 1 and Type 2 LSA?
What is Type 1 and Type 2 LSA?
Type 1 LSAs are used to advertise the router and its connected networks participating in OSPF. Type 2 LSAs are used to advertise only the routers within the same OSPF area on the same network (multi-access) segment.
What is a Type 3 LSA?
The Summary (Type 3) LSA is used for advertising prefixes learned from the Type 1 and Type 2 LSAs into a different area. The Area Border Router (ABR) is the OSPF device that separates areas and it is this device that advertises the Type 3 LSA.
What is a Type 5 LSA?
The type-5 LSA is the external LSA. As the name suggests, it describes networks that are external to the OSPF domain, injected into OSPF via some form of redistribution. When redistributing into OSPF, the routes can be of two types – E1 and E2 external routes.
What is a Type 2 LSA?
LSA Type 2 – OSPF Network LSA LSA Type 2 (Network LSA) packets are generated by the Designated Router (DR) to describe all routers connected to its segment directly. LSA Type 2 packets are flooded between neighbors in the same area of origin and remain within that area.
Why is LSA type 4 needed?
So, a type-4 asbr-summary LSA is needed to help make the ASBR reachable and, by extension make the associated type-5 prefix valid. The type-4 acts like a glue record, and uses the ABRs well known RID as a care-of address for the ASBR and it’s advertised prefixes.
What is Type 7 LSA?
Type 7 – External LSA: also known as not-so-stubby-area (NSSA) LSA: As you can see area 2 is a NSSA (not-so-stubby-area) which doesn’t allow external LSAs (type 5).
What defines the relationship between Type 5 and Type 7 LSAs?
The difference between Type-5 LSA and Type-7 LSA is that Type-7 LSA can live only into NSSA area, so it will never leave the NSSA area. Instead Type-5 LSA can be propagated to the other areas (backbone and non-backbone). – Both of them are generated by the ASBR.
What is Type 2 LSA?
What is LSA and Lsdb?
These packets are called link-state advertisements (LSAs), and they describe the network topology in great detail. Each router stores the received LSA packets in the link-state database (LSDB). After LSDBs are synced between the routers, OSPF uses the shortest path first (SPF) algorithm to calculate the best routes.
What is a Type 1 LSA?
LSA Type 1 (Router LSA) packets are sent between routers within the same area of origin and do not leave the area. An OSPF router uses LSA Type 1 packets to describe its own interfaces but also carries information about its neighbors to adjacent routers in the same area.
What is NSSA and totally NSSA?
Area 10 is not just NSSA, it is a totally NSSA. The difference is that stubby areas don’t allow any type 5 LSAs to get in, so if there are any type 5 LSAs to be advertised into the area, they are all replaced with a default route. But type 3 LSAs are permitted and are advertised.
What is a type 5 LSA?
They are generated by the ASBR within the NSSA to describe external routes that are redistributed into the area. The type 7 LSA stays within the NSSA as well. When it leaves the NSSA, it is translated to a type 5 LSA by the ABR. These routes show up in the routing table with the N1 and N2 designation.
What are the different types of LSA generated by the ABR?
This is why the ABR will generate a summary ASBR LSA which will include the router ID of the ASBR in the link-state ID field. Type 5 – External LSA: also known as autonomous system external LSA: The external LSAs are generated by the ASBR. Type 6 – Multicast LSA: Not supported and not used.
What are the different types of osospf LSA?
OSPF LSA Types Explained. 1 LSA Type 1: Router LSA. 2 LSA Type 2: Network LSA. 3 LSA Type 3: Summary LSA. 4 LSA Type 4: Summary ASBR LSA. 5 LSA Type 5: Autonomous system external LSA. 6 LSA Type 6: Multicast OSPF LSA. 7 LSA Type 7: Not-so-stubby area LSA. 8 LSA Type 8: External attribute LSA for BGP.
What is the difference between Type 1 and Type 2 LSA?
Type 1 – Router LSA: The Router LSA is generated by each router for each area it is located. In the link-state ID you will find the originating router’s ID. Type 2 – Network LSA: Network LSAs are generated by the DR.