3Com Switch 4800G 24-Port Configuration Manual page 286

286 C 28: OSPF C
HAPTER ONFIGURATION
Figure 84 LSR packet format
0
Version
Major fields:
LS type: Type number of the LSA to be requested. Type 1 for example indicates
■
the Router LSA.
Link State ID: Determined by LSA type.
■
Advertising Router: ID of the router that sent the LSA.
■
LSU packet
LSU (Link State Update) packets are used to send the requested LSAs to peers, and
each packet carries a collection of LSAs. The LSU packet format is shown below.
Figure 85 LSU packet format
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Version
LSAck packet
LSAack (Link State Acknowledgment) packets are used to acknowledge received
LSU packets, contents including LSA headers to describe the corresponding LSAs.
Multiple LSAs can be acknowledged in a single Link State Acknowledgment
packet. The following figure gives its format.
7 15
3
Router ID
Area ID
Checksum
Authentication
Authentication
LS type
Link state ID
Advertising router
7 15
4
Router ID
Area ID
Checksum
Authentication
Authentication
Number of LSAs
LSA
LSA
Packet length
AuType
...
Packet length
AuType
31
31