A Type 2 LSA, or Network LSA, is generated by the designated router (DR) on a broadcast network. It lists every router on that segment, helping OSPF describe the shared network. section 18.4 section 18.5
Key points:
- Only the DR generates the Type 2 LSA for the broadcast segment. section 18.4
- A broadcast interface with no OSPF neighbors may have a DR in name only and produce no Type 2 LSA. section 18.4
- Use show ip ospf database to inspect Net Link States and verify the advertised network LSA. section 18.4
Reading the LSDB
In the R2–R3–R4–R5 broadcast segment, R5 is the DR and advertises the Type 2 LSA. The command output identifies it under Net Link States. section 18.4
Figure 18.14 An OSPF AS and the contents of its LSDB. Each router advertises a type 1 (Router) LSA. R5, as the DR of the R2–R3–R4–R5 segment, advertises a type 2 (Network) LSA. R1, as an ASBR, advertises a type 5 LSA.
A topology and LSDB diagram shows how the DR's Type 2 LSA represents all routers on a shared broadcast segment. section 18.4
