Networks

Multiple computer and other devices connected to exchange data

• Global network: Internet

• Local network: domitory network

• Each computer can be a client (use resources), server (shares resource) or be both

• For small network (up to 10 computers)

• Each user decides what will be shared with others

• Devices are divided into offering resources (server) and using resources (client)

• Used in lager networks

• Network managing by an administrator

• Local area network

• Consist of small areas (room, building)

• High data delivery capabilities

• Max. range with amplifiers 1km

• Metropolitan area network

• Range of city

• Usually high data delivery capabilities

• Allow to connect local networks (academic / administration work)

• Wide area network

• Wide range and often continental

• Based on public communication networks (telephone, radio, satellite)

Cables and fiber optics used to connect elements

= Wireless network

• All elements or their part are connected wirelessly

= Virtual network

• Network elements are connected by program protocol which manage network movement

• Transmission devices (copper and fiber optic cables)

• Access devices (network interface cards, modems)

• Signal amplification devices (repeaters, hubs)

• Protocols (e.g. TCP / IP)

• Device driver: Enables other devices, e.g. network cards)

• Communication software: Allows transmission of data (e.g. web browsers, e-mail)

• Connection is based on one coaxial cable (bus)

• Used in small networks

• Easy to connect with new workstations

• An issue causes whole network outage

• One transmission in one moment

• Each workstation has 2 connections with neighbors (together they create a loop)

• Data is sent in one direction

• An issue causes whole network outage

• Difficult to connect new devices

• Connection comes from central point (hub)

• High bandwidth

• Easy to allocate issues

• High demand for cables

• It dominates in LAN networks

• Based on star topology

• Used in big networks

• Workstations are connected with eachother

• High costs and complicated architecture

• Reliability

• Connects computer with local network

• Change data packages into signals

• Most common is Ethernet (it has unique MAC address which is assigned in ROM to individual computer)

• Allows to communicate between computers from local network and computers from other networks

• In TCP / IP default gate is router

• Usually gateway connects network with same protocols

• Worldwide network

• Connection between many small local networks (private, public, academic, business, government) which are connected by special standards and protocols

• Connection is based on IP (internet protocol)

• Started on 20. century

• Started in military industries

• DARPA: Built network between 4 universities (first use was based one simple text messages)

• MILNET: Built network because of hacker attacks

• APARNET: Fundamental for commercial network which was the base for internet creations

Numerical value assigned to each device connected to computer network 32-bit number (4 bytes) written in decimal notation

For all network elements where we can't accept any margin of errors

• For all network elements where we can accept margin of errors

• Not all data needs sending confirmation (video streaming, voice calls, sound listing)

• 4 layers

  • Application

  • transport

  • internet

  • link

• 7 layers

  • Application

  • presentation

  • session

  • transport

  • network

  • datalink

  • physical

• Directly connected with cables

• Allows to connect user to network or with wireless signal

• Cable has millions of fibers and is well secured (e.g. steel housing)

• Internet is based on land links and underwater links

• Connection is bases on million cables and the connections between them

• Connected with MAC addresses

• One local network with one IP address can include many devices

• Number of public IP addresses is limited (IP addresses are unique so can't be repeated)

• Router translates private addresses into public one

Each device receives a MAC address (it allow the communication with switches) 48-bits (shown in hexadecimal notation)

• Based on IP address

• Directly connected with router

• Allows a smooth data transfer

• Keeps addresses to change way of data transfer on case of any malfunctions

• Static protocol: Like a map with different ways

• Dynamic protocols: Like a navigation, always chooses the best way

• Consists of Router, access point and switch

• Connects local home network with internet

• Routers at home are at the same time DHCP server

• Service which determines IP for other devices

• Has set of IP addresses and assign first free address to device which requested it

• Thanks to it we can see how MAC address is assign to IP address

• Automatically completes host configuration

• Created by US company SPACE X (Elon Musk)

• Goal: Provide internet connection from anywhere on earth

• First Satellite launched in 2019

• Objections of astronomer because it impacts their research

• Provided by mobile operators

• Disadvantage: Data transfer limit and uncertain stability of connection

• Device or installed on it

• Software which provide service by sharing resources to other user

• Provide access to many websites each day

• Network of remote server

• Stores data and allow to manage them with any device

• Needs to have an internet connection

• Full control on architecture

• Owner needs to fully cover costs of maintaining the device, replacement of components and software update

• Service provided by outside supplier

• Provides computing power and disk space which is part of the purchased package

• Maintenance cost are on the supplier side

= Directly attach storage

• External drive which is connected with cable to the computer

• Access is possible only from location of data carrier

• Advantage: Fast working and we can work directly with the data

= Network attached storage

• Drive is connected to the network

• Advantage: Data isn’t in foreign hands

• Public cloud: Whole infrastructure in supplier location, service is delivered by internet, client doesn't need own IT system

• Private cloud: Biggest level of safety and control, used only by one enterprise, host is located in enterprise or datacenter

• Hybrid cloud: Merge between both, most important applications are located on own server and the rest on suppliers server

• IBARD (Comarch)

• Google drive

• iCloud

• Dropbox

• One Drive