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H3C Technologies H3C S7500E Series Switches User Manual

Page 85

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Figure 4-17 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 4-18 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