D-Link DES-3326S manual Link-State Request Packet, 148

DES-3326S Layer 3 Fast Ethernet Switch User’s Guide

The Link-State Request Packet

Link-State Request packets are OSPF packet type 3. After exchanging Database Description packets with a neighboring router, a router may find that parts of its topological database are out of date. The Link-State Request packet is used to request the pieces of the neighbor’s database that are more up to date. Multiple Link-State Request packets may need to be used. The sending of Link-State Request packets is the last step in bringing up an adjacency.

A router that sends a Link-State Request packet has in mind the precise instance of the database pieces it is requesting, defined by LS sequence number, LS checksum, and LS age, although these fields are not specified in the Link-State Request packet itself. The router may receive even more recent instances in response.

The format of the Link-State Request packet is shown below:

Link-State Request Packet

Version No.

3 Packet Length

Router ID

Area ID

Checksum Authentication Type

Authentication

Authentication

Link-State Type

Link-State ID

Advertising Router

148 Switch Management and Operating Concepts