Thus, even a transit link of a point-to-point OSPF type will not be modelled as transit network because there is no DR (i.e. The Link Type 2 - a transit network - references the IP address of the Designated Router but such a router is elected only on multiaccess network types. Read these two tables from RFC 2328 closely: if two routers are interconnected by a point-to-point link, even if that link is naturally a transit link, it will be modelled in LSA1 using Link Type 1 (point-to-point link) referencing the neighbor's RID, and another entry describing the actual IP subnet located on this point-to-point link as a stub network. This is given by the LSA1 link types and their associated IDs:ġ Point-to-point connection to another router A point-to-point connection between two routers, even if being naturally a transit link, is not described as a transit network in the LSA1.
Regarding the stub/transit network definition, for OSPF, only a multiaccess network type with at least two routers is considered a transit network.
