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| Field |
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| Description | |
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| Link State Age |
| The | time is seconds since the link state advertisement was | ||
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| originated. | ||
| Options |
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| The optional capabilities supported by the described portion of | ||
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| the routing domain. | ||
| Link State Type |
| The type of the link state advertisement. Each link state type | |||
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| has a separate advertisement format. The link state type are as | ||
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| Type | Description | |
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| 1 | Router Links | |
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| 2 | Network Links | |
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| 3 | Summary Link (IP Network) | |
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| 4 | Summary Link (ASBR) | |
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| 5 | AS External Link | |
| Link State ID |
| This field identifies the portion of the internet environment that | |||
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| is being described by the advertisement. The contents of this | ||
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| field depend on the advertisement’s Link State Type. | ||
| Advertising Router | The | Router ID of the router that originated the Link State | |||
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| Advertisement. For example, in network links advertisements | ||
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| this field is set to the Router ID of the network’s Designated | ||
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| Router. | ||
| Link | State | Sequence | Detects old or duplicate link state advertisements. Successive | ||
| Number |
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| instances of a link state advertisement are given successive Link | ||
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| State Sequence numbers. | ||
| Link State Checksum | The | Fletcher checksum of the complete contents of the link | |||
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| state advertisement, including the link state advertisement | ||
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| header except for the Link State Age field. | ||
| Length |
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| The | length in bytes of the link state advertisement. This | |
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| includes the | ||
Table
Router Links Advertisements
Router links advertisements are type 1 link state advertisements. Each router in an area originates a routers links advertisement. The advertisement describes the state and cost of the router’s links to the area. All of the router’s links to the area must be described in a single router links advertisement.
The format of the Router Links Advertisement is shown below:
80
