Figure 33 Network LSA format
Major fields of the Network LSA are as follows:
Link state ID: The interface address of the DR.
•
•
Network mask: The mask of the network (a broadcast or NBMA network).
Attached router: The IDs of the routers, which are adjacent to the DR, including the DR itself.
•
Summary LSA
3.
Network summary LSAs (Type-3 LSAs) and ASBR summary LSAs (Type-4 LSAs) are originated by ABRs.
Except for the Link state ID field, the formats of Type 3 and 4 summary-LSAs are identical.
Figure 34 Summary LSA format
Major fields of the Summary LSA are as follows:
Link state ID: For a Type-3 LSA, it is an IP address outside the area. For a type 4 LSA, it is the router
•
ID of an ASBR outside the area.
Network mask: The network mask for the type 3 LSA. It is set to 0.0.0.0 for the Type-4 LSA.
•
Metric: The metric to the destination.
•
NOTE:
A Type-3 LSA can be used to advertise a default route if the link state ID and network mask are set to
0.0.0.0.
AS external LSA
4.
69