D-Link DGS-3120-24PC/*RI Руководство пользователя _Web UI_ онлайн [194/509] 385520

xStack® DGS-3120 Series Layer 3 Managed Gigabit Ethernet Switch Web UI Reference Guide

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Parameter Description

Version No.

The OSPF version number.

Type

The OSPF packet type. The OSPF packet types are as follows: Type Description Hello

Database Description Link-State Request Link-State Update Link-State

Acknowledgment.

Packet Length

The length of the packet in bytes. This length includes the 24-byte header.

Router ID

The Router ID of the packet’s source.

Area ID

A 32-bit number identifying the area that this packet belongs to. All OSPF packets are

associated with a single area. Packets traversing a virtual link are assigned the

backbone Area ID of 0.0.0.0

Checksum

A standard IP checksum that includes all of the packet’s contents except for the 64-bit

authentication field.

Authentication Type

The type of authentication to be used for the packet.

Authentication

A 64-bit field used by the authentication scheme.

Hello Packet

Hello packets are OSPF packet type 1. They are sent periodically on all interfaces, including virtual links, in order to

establish and maintain neighbor relationships. In addition, Hello Packets are multicast on those physical networks

having a multicast or broadcast capability, enabling dynamic discovery of neighboring routers.

All routers connected to a common network must agree on certain parameters such as the Network Mask, the Hello

Interval, and the Router Dead Interval. These parameters are included in the hello packets, so that differences can

inhibit the forming of neighbor relationships. A detailed explanation of the receive process for Hello packets is

necessary so that differences cannot inhibit the forming of neighbor relationships.

The format of the Hello packet is shown below: