What Are Different Ospf Lsa Types ?

1.	What Are Different Ospf Lsa Types ?
Answer» Router LSA (Type1) - Each router generates a Type 1 LSA that lists its ACTIVE interfaces, IP addresses, neighbors and the cost. LSA Type 1 is flooded only within an AREA. Network LSA (TYPE2) - Type 2 LSA is sent out by the designated router (DR) and lists all the routers on the segment it is adjacent to. Type 2 LSA are ﬂooded only within an area. It contains the information about DR's. Summary LSA (Type3) - Type 3 LSAs are generated by Area Border Routers (ABRs) to advertise networks from one area to the rest of the areas in Autonomous System. It contains the information about inter-area routes. Summary ASBR LSA (Type4) - It is generated by the ABR and contain routes to ASBRs. External LSA (Type5) - External LSAs are generated by ASBRs and contain routes to networks that are external to CURRENT AS. Not-So-Stubby Area LSA (Type7) - Stub areas do not ALLOW Type 5 LSAs. A Not So Stubby Area (NSSA) allows advertisement of Type 5 LSA as Type 7 LSAs. Type LSA is generated by an ASBR inside a Not So Stubby Area (NSSA) to describe routes redistributed into the NSSA.

Answer»

Router LSA (Type1) - Each router generates a Type 1 LSA that lists its ACTIVE interfaces, IP addresses, neighbors and the cost. LSA Type 1 is flooded only within an AREA.
Network LSA (TYPE2) - Type 2 LSA is sent out by the designated router (DR) and lists all the routers on the segment it is adjacent to. Type 2 LSA are ﬂooded only within an area. It contains the information about DR's.
Summary LSA (Type3) - Type 3 LSAs are generated by Area Border Routers (ABRs) to advertise networks from one area to the rest of the areas in Autonomous System. It contains the information about inter-area routes.
Summary ASBR LSA (Type4) - It is generated by the ABR and contain routes to ASBRs.
External LSA (Type5) - External LSAs are generated by ASBRs and contain routes to networks that are external to CURRENT AS.
Not-So-Stubby Area LSA (Type7) - Stub areas do not ALLOW Type 5 LSAs. A Not So Stubby Area (NSSA) allows advertisement of Type 5 LSA as Type 7 LSAs. Type LSA is generated by an ASBR inside a Not So Stubby Area (NSSA) to describe routes redistributed into the NSSA.

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