[HCIA] data communication network foundation

Catalog

Introduction to digital communication

Common terms

Common equipment 、 Conflict domain and broadcast domain

         A hub

         Switch

         Router

LAN 、 Metropolitan area network 、 Wide area network

Introduction to digital communication

Digital communication ： The communication between two devices is called data communication , Abbreviation of data communication .

Common terms

Data load ： The data you ultimately want to convey

encapsulation ： Add headers and tails to the data payload

Head ： Add the data segment before the data payload

The tail ： Add the data segment after the data payload

message ： Data after encapsulation

decapsulation ： Remove the header and tail of the message , The process of obtaining data load

gateway ： Also known as inter network connector , Realize network interconnection above the network layer

Terminal equipment ： A device that transmits data

Basic transmission equipment 、 Conflict domain and broadcast domain

The basic transmission equipment includes ： A hub 、 Switch 、 Router

Conflict domain ： Areas where multiple devices cannot send data at the same time

Broadcast area ： A device sends data , The area where all devices can receive this data

         A hub

  The hub cannot be divided into conflict domain and broadcast domain .

prove ：

When PC1 to PC2 When sending data ,PC3 You will also receive this data .

  to PC3 When caught , Shows that it received a message from PC1 issue PC2 Message of , because PC2 After receiving it, you need to give PC1 Respond , And this is another conflict domain , therefore PC3 I got it again PC2 issue PC1 Response message for .

         Switch

The switch can split the conflict domain , But the broadcast domain cannot be divided .

  prove ：

When PC1 to PC2 When sending data ,PC3  This data will not be received , But you'll get PC1  Emitted ARP.

         Router

  The router can divide the conflict domain and the broadcast domain .

prove ：

When PC1 to PC2 When sending data ,PC3  This data will not be received , I won't receive PC1  Emitted ARP.

LAN 、 Metropolitan area network 、 Wide area network

LAN

Range ： Within a few thousand meters

example ： company 、 Internet cafes 、 family 、 School

Metropolitan area network

Range ： In a city

example ： Municipal or provincial E-government Network

Wide area network

Range ： Connect multiple cities and even countries

example ： The Internet