DXS-3350SR Gigabit Layer 3 Switch
The Link State Advertisement Header
All link state advertisements begin with a common 20-byte header. This header contains enough information to uniquely
identify the advertisements (Link State Type, Link State ID, and Advertising Router). Multiple instances of the link state
advertisement may exist in the routing domain at the same time. It is then necessary to determine which instance is more
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
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.
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Summary of Contents for xStack DXS-3350SR
Page 114: ...DXS 3350SR Gigabit Layer 3 Switch Figure 6 56 Access Profile Configuration IP 105 ...
Page 118: ...DXS 3350SR Gigabit Layer 3 Switch Figure 6 59 Access Rule Configuration window IP window 109 ...
Page 125: ...DXS 3350SR Gigabit Layer 3 Switch Figure 6 66 Access Rule Display Packet Content 116 ...
Page 129: ...DXS 3350SR Gigabit Layer 3 Switch Figure 6 70 Second 802 1X Authenticator Settings menu 120 ...
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