LSA Types

The OSPF LSDB is made up of LSAs.

There are 11 types of LSA, but there are only 3 you should be aware of for the CCNA:

1. Type 1 (Router LSA)

2. Type 2 (Network LSA)

3. Type 5 (AS External LSA)

Type 1

• Every OSPF router generated this type of LSA.

• It identifies the router using its router ID.

• It also lists networks attached to the router's OSPF-activated interfaces.

Type 2

• Generated by the DR of each 'multi-access' network (ie. the broadcast network type).

• Lists the routers which are attached to the multi-access network.

Type 5

• Generated by ASBRs to describe routes to destinations outside of the AS (OSPF domain).