D-Link DES-3326SRM Product Manual - Page 179

Link-State Advertisement Header

Page 179 highlights

D-Link DES-3326S Layer 3 Switch recent. This is accomplished by examining the link state age, link state sequence number and link state checksum fields that are also contained in the link state advertisement header. The format of the Link State Advertisement Header is shown below: Link-State Advertisement Header Link-State Age Options Link-State Type Link-State ID Advertising Router Link-State Sequence Number Link-State Checksum Table 8. Link-State Advertisement Header Length Field Link State Age Options Link State Type Link State ID Advertising Router Link State Sequence Number Link State Checksum Length Description The time is seconds since the link state advertisement was originated. The optional capabilities supported by the described portion of the routing domain. The type of the link state advertisement. Each link state type has a separate advertisement format. The link state type are as follows: Type Description 1 Router Links Network Links Summary Link (IP Network) Summary Link (ASBR) AS External Link This field identifies the portion of the internet environment that is being described by the advertisement. The contents of this field depend on the advertisement's Link State Type. The Router ID of the router that originated the Link State Advertisement. For example, in network links advertisements this field is set to the Router ID of the network's Designated Router. Detects old or duplicate link state advertisements. Successive instances of a link state advertisement are given successive Link State Sequence numbers. The Fletcher checksum of the complete contents of the link state advertisement, including the link state advertisement header by excepting the Link State Age field. The length in bytes of the link state advertisement. This includes the 20-byte link state advertisement header. 169

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D-Link DES-3326S Layer 3 Switch
recent.
This is accomplished by examining the link state age, link state sequence number and link state checksum fields that
are also contained in the link state advertisement header.
The format of the Link State Advertisement Header is shown below:
Link-State Advertisement Header
Link-State Age
Options
Link-State Type
Link-State ID
Advertising Router
Link-State Sequence Number
Link-State Checksum
Length
Table 8. Link-State Advertisement Header
Field
Description
Link State Age
The time is seconds since the link state advertisement was
originated.
Options
The optional capabilities supported by the described portion of
the routing domain.
Link State Type
The type of the link state advertisement.
Each link state type has
a separate advertisement format.
The link state type are as
follows:
Type
Description
1
Router Links
Network Links
Summary Link (IP Network)
Summary Link (ASBR)
AS External Link
Link State ID
This field identifies the portion of the internet environment that is
being described by the advertisement. The contents of this field
depend on the advertisement’s Link State Type.
Advertising Router
The Router ID of the router that originated the Link State
Advertisement.
For example, in network links advertisements this
field is set to the Router ID of the network’s Designated Router.
Link State Sequence
Number
Detects old or duplicate link state advertisements.
Successive
instances of a link state advertisement are given successive Link
State Sequence numbers.
Link State Checksum
The Fletcher checksum of the complete contents of the link state
advertisement, including the link state advertisement header by
excepting the Link State Age field.
Length
The length in bytes of the link state advertisement.
This includes
the 20-byte link state advertisement header.
169