H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – IPv4 Routing
H3C S7500E Series Ethernet Switches Chapter 3 OSPF Configuration
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VI. 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.
Figure 3-14 LSAck packet format
VII. LSA header format
All LSAs have the same header, as shown in the following figure.
Figure 3-15 LSA header format
Major fields:
z LS age: Time in seconds elapsed since the LSA was originated. A LSA ages in the
LSDB (added by 1 per second), but does not in transmission.
z LS type: Type of the LSA.
z Link State ID: The contents of this field depend on the LSA's type
z LS sequence number: Used by other routers to judge new and old LSAs.
z LS checksum: Checksum of the LSA except the LS age field.
z Length: Length in bytes of the LSA, including the LSA header.
VIII. Formats of LSAs
1) Router LSA