D-Link DES-6500 - Switch User Manual page 161

Link-State Advertisement Formats
There are five distinct types of link-state advertisements. Each link-state advertisement begins with a standard 20-byte link-state
advertisement header. Succeeding sections then diagram the separate link-state advertisement types.
Each link-state advertisement describes a piece of the OSPF routing domain. Every router originates a router links advertisement.
In addition, whenever the router is elected as the Designated Router, it originates a network links advertisement. Other types of
link-state advertisements may also be originated. The flooding algorithm is reliable, ensuring that all routers have the same
collection of link-state advertisements. The collection of advertisements is called the link-state (or topological) database.
From the link-state database, each router constructs a shortest path tree with itself as root. This yields a routing table.
There are four types of link state advertisements, each using a common link state header. These are:
Router Links Advertisements
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Network Links Advertisements
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Summary Link Advertisements
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Autonomous System Link Advertisements
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xStack DES-6500 Modular Layer 3 Chassis Ethernet Switch User Manual
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