Specifications

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10.9.11 Link State Database
Choose the menu Routing→OSPF→Link State Database to load the following page.
Figure10-56 Link State Database
The following entries are displayed on this screen:

Link State Database
Process: Select one OSPF Process to display its link state database.
Area ID: Displays the ID of the area to which the LSA belongs.
Advertising Router: Displays the ID of the router that advertising the LSA.
LSA Type:
The format and function of the link state advertisement. One of
the following: Router, Network, Network-
Summary,
ASBR-Summary, External (Type 5), NSSA-External (Type 7).
Link State ID:
The Link State ID identifies the piece of the routing domain
that is being described by the advertisement. The value of the
LS ID depends on the advertisement's LS type.
Age:
The time since the link state advertisement was first
originated, in seconds.
Sequence: The sequence number field is an unsigned 32-
bit integer. It is
used to detect old and duplicate link state advertisements. The
larger the sequen
ce number, the more recent the
advertisement.
Checksum:
The checksum is used to detect data corruption of an
advertisement. This corruption can occur while an
advertisement is being flooded, or while it is being held in a
router's memory. This field is th
e checksum of the complete
contents of the advertisement, except the LS age field.
Options:
The Options field in the link state advertisement header
indicates which optional capabilities are associated with the
advertisement.
10.9.12 Application Example for OSPF
 Network Requirements
1. The AS is divided into three areas and all switches in the AS run OSPF.
2. Switch A and Switch B act as ABRs to forward routing information between areas.
3. Each switch can learn routing information to all the network segments in the AS after the
configuration.