Active and passive devices in a computer network

In today's article, we will describe the basic passive and active devices necessary to create a computer network.

computer network

• are two or more computers connected by a cable, through which they can exchange information.

• allows users to jointly use peripheral devices enables common and easy access to programs and databases and the exchange of information between other computer systems.

• We divide these networks into local ones ,metropolitanne
• the network consists mainly of hosts ,servers ,transmission medium ,network hardware and software

Active devices

verifier(router):

- I work in 3 layer of the OSI model

-connect different types of networks, e.g.. LAN , MAN , VAN (they pass packets in between)

-by directing packets to the target network, they choose the best path for them

(has routing tables)

-it is available in the ADSL and Ethernet variant

- divides the LAN into broadcast and collision domains

 

concentrator (hub):

-I work in 1 layer of the OSI model

-connects devices in a star topology network

-it amplifies the incoming signal and forwards it to the other ports

-The concentrator comes in three types : passive , intelligent , switching

switch (switch):

-I work in 2 layer of the OSI model

-forwards frames that are sent based on MAC addresses

-can work in 4 modes such as : cut-through , store and forward , fragment free , adaptive switching

-it is used in networks mainly with star topology where it is the central point of the network

regenerator (repeater)/access point:

*regenerator

-I work in 1 layer of the OSI model

-connects network segments

-as the name suggests , strengthens , regenerates the signal and thus increases the length of the network segment

*access point

-provides wireless stations with access to network resources via radio waves

-connects the wireless network to the wired network

-it is used to build BSS and ESS networks

most (bridge):

-I work in 2 layer of the OSI model

-creates a minimum 2 network segments

-filters frames , routes data transmission based on IP addresses

-it can be found in three types , like : transparent , LSB ,performing source routing

Network card(THREAD - Network Interface Card)

- in the case of the TCP / IP model, it works in the network access layer

-provides communication with a computer network

- has a MAC address

-works at speed 10,100,1000 Mb / s in Ethernet standards ,

Fast Ethernet , Gigabit Ethernet

-it is built into network devices

-They are divided into external connected via USB and internal connected via PCI slot ,PCMCIA or embedded in the motherboard (integrated)

transceiver:

Transceiver device connecting the AUI port (Attachment Unit Interface) network device with the type of wiring used for transmission. In addition to sending and receiving data, it performs collision detection functions (with the simultaneous appearance of data packets), it does not allow too long transfers (>20 ms) data packets (Jabber function) and detects breaks in the fiber optic line.

Passive network elements

*they are used to amplify and transmit the signal

Transmission medium:

Coaxial Cable:

-used in ring or bus topology networks

-max transmission speed 10 Mb / s

-max network length 500 m

-is divided into 10Base2 thin coaxial cable(where the max segment length is 185 , np RG-58) and the coaxial thick 10Base5 standard (e.g. RG8 , 11)

-resistant to interference but susceptible to damage and difficult to locate the fault

-the best known BNC connector used

symmetrical cable (twisted pair):

-consists of 4 pairs of twisted copper wires (twisting allows to eliminate electromagnetic interference)

-mainly used in star topology

-the four main types of this cable will be : U / UTP , F/UTP , S/FTP, SF/UTP

-connectors used : RJ-45 and RJ-11

optical fiber

-the data is transmitted as a light beam

-they are characterized by high throughput , noise immunity , transmission over long distances

-they are single-mode , multi-mode or step ,gradient and stripe , planar and fibrous

-used in telephone lines , telecommunications networks , cable TV etc..

-FC connectors ,LC , SC , ST

patchcord

- short connecting cable, e.g.. network devices with a workstation

radio waves and infrared

-transmit the signal wirelessly using the frequency ranges from 3 kHz do 3 THz

-patch panel

-cable organizers

-computer plugs,sockets

-wardrobe (rack)

-mounting frames

-PVC troughs