3com S7906E Manuel De Montage
1-16
Figure 1-17 Network LSA format
Network mask
...
Attached router
LS age
Link state ID
Advertising router
Options
2
LS sequence number
LS checksum
Length
0
7
15
31
Major fields:
z
Link State ID: The interface address of the DR
z
Network mask: The mask of the network (a broadcast or NBMA network)
z
Attached router: The IDs of the routers, which are adjacent to the DR, including the DR itself
3) Summary
LSA
Network summary LSAs (Type-3 LSAs) and ASBR summary LSAs (Type-4 LSAs) are originated by
ABRs. Other than the difference in the Link State ID field, the format of type 3 and 4 summary-LSAs is
identical.
Figure 1-18 Summary LSA format
Major fields:
z
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.
z
Network mask: The network mask for the type 3 LSA; set to 0.0.0.0 for the Type-4 LSA
z
Metric: The metric to the destination