LSA Type 2: Network LSA
Lesson 3: Type 2 LSA: Network
SPF requires that the LSDB model the topology with nodes (routers) and connections between nodes (links). In particular, each link must be between a pair of nodes. When a multiaccess data link exists—for example, a LAN—OSPF must somehow model that LAN so that the topology represents nodes and links between only a pair of nodes. To do so, OSPF uses the concept of a Type 2 Network LSA.
OSPF routers actually choose whether to use a Type 2 LSA for a multiaccess network based on whether a designated router (DR) has or has not been elected on an interface. So, before discussing the details of the ...