3Com MSR 50 Series Configuration Manual page 931

Figure 282 LSAck packet format
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Version
Checksum
LSA header format
All LSAs have the same header, as shown in the following figure.
Figure 283 LSA header format
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LS age
LS checksum
Major fields:
LS age: The time in seconds elapsed since the LSA was originated. A LSA ages
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in the LSDB (added 1 per second), but does not in transmission.
LS type: The type of the LSA
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Link State ID: The contents of this field depend on the LSA's type
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LS sequence number: Used by other routers to judge new and old LSAs.
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LS checksum: Checksum of the LSA except the LS age field
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Length: The length in bytes of the LSA, including the LSA header
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15
5
Router ID
Area ID
Authentication
Authentication
LSA header
LSA header
15
Options
Linke state ID
Advertising Router
LS sequence number
Introduction to OSPF 931
Packet length
AuType
LS type
Length
31
31