DES-3326S Layer 3 Fast Ethernet Switch User’s Guide
150 Switch Management and Operating Concepts
Version No.
Pa
Router ID
Area ID
Au
Authentication
Authentication
Checksum
Link-State Update Packet
4
Number of Advertisemen
Link-State Advertisement
cket Length
thentication Type
ts
s ...
Figure 5-26. Link-State Update Packet
The body of the Link-State Update packet consists of a list of
link-state advertisements. Each advertisement begins with a
common 20-byte header, the link-state advertisement header.
Otherwise, the format of each of the five types of link-state
advertisements is different.
The Link-State Acknowledgment Packet
Link-State Acknowledgment packets are OSPF packet type 5.
To make the folding of link-state advertisements reliable,
flooded advertisements are explicitly acknowledged. This
acknowledgment is accomplished through the sending and
receiving of Link-State Acknowledgment packets. Multiple
link-state advertisements can be acknowledged in a single
Link-State Acknowledgment packet.
Depending on the state of the sending interface and the source
of the advertisements being acknowledged, a Link-State
Acknowledgment packet is sent either to the multicast address
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