Chapter 3

Communication

Technology

Computer Network

… is a telecommunications network that allows computers to exchange data. In computer networks, networked computing devices pass data to each other along data connections. The connections (network links) between nodes are established using either cable media or wireless media. The best-known computer network is the Internet.

Network Element

1.Sender – devices or sources send data/information

2.Data - message which was sent from sender to receiver

3.Receiver – destination of data/information

4.Media – the way used for passing the data/information

5.Protocol - the principal communications protocol in the Internet protocol suite for relaying datagrams across network boundaries.

Network element

Devices for Network

Computer Network Interface Card (NIC)

Physical Media – Twist pair , Coaxial , Fiber optic, Wireless

Protocol – TCP/IP Network Operating System (NOS)

Benefits of Network

Sharing resource Reduced cost Comfortable Safety for system

Type of Data

Communication

1.Unicast

… communication where a piece of information is sent from one point to another point. In this case there is just one sender, and one receiver. Or called One-to-One

2. Broadcast … communication where a piece of information is sent from one point to all other points. In this case there is just one sender, but the information is sent to all connected receivers. Or called One-to-All

3. Multicast … communication where a piece of information is sent from one or more points to a set of other points. In this case there is may be one or more senders, and the information is distributed to a set of receivers.

Communication

Direction

1.Simplex2.Half-Duplex3.Full-Duplex

1.Simplexcommunication that occurs

in one direction only. An example of a simplex device is a television, radio, satellite etc.

Communication

Direction

2. Half-Duplex the communication is one direction at a time. An example of a half-duplex device is a walkie-talkie two-way radio that has a "push-to-talk" button

Communication

Direction

3. Full-Duplexboth parties can

communicate to the other simultaneously. An example of a full-duplex device is a telephone

Communication

Direction

Type of Network

1.by flow of data2.by function of computer3.by size of service

Centralized Network

flow of data

Distributed Network

flow of data

Peer to Peer OR Workgroup

Client Server

Function of Comp.

LAN , MAN , WAN

Size of Network

… is a network confined to one building or site. Often a LAN is a private network belonging to an organization or business.

… is a network that extends over a large area. A WAN is often created by joining several LANs together, such as when a business that has offices in different countries links the office LANs together.

๐ What’s Ethernet ??? … is a family of computer networking technologies for LANs. The original 10 megabits per second used twisted pair. Later the coaxial cables were replaced with twisted pair, data rates were periodically increased from the original 10 megabits per second to 100 gigabits per second.

1.LANs are most likely based on Ethernet technology, Token Ring, FDDI

Networking Standard

Wire

1.2 Token-Ring … is a protocol which

resides at the data link layer (DLL) of the OSI model. It used a special three-byte frame called a token that travels around the ring. Token-possession grants the possessor permission to transmit on the medium. Token ring frames travel completely around the loop. It was eventually standardized with protocol IEEE 802.5

1.3 FDDI (Fiber Distributed Data Interface)

… is a standard for data transmission in a local area network. It uses optical fiber as its standard underlying physical medium. It’s protocol was derived from the IEEE 802.4 token bus

Wireless

… is any type of computer network that uses wireless data connections for connecting network nodes, or as a connection between various equipment locations.

Type of Wireless

1.WPAN (wireless personal area network)

2.WLAN (wireless local area network)

3.WMAN (wireless metropolitan area network)

4.WWAN (wireless wide area network)

1.WPAN… is a computer network

used for wireless data transmission among devices such as computers, telephones and personal digital assistants such asIR (Infra-Red) , Bluetooth , NFC

2. WLAN is a LAN that uses radio

signals (WiFi) to connect computers instead of cables.

3. WMAN … is optimized for a larger geographical area than a LAN, ranging from several blocks of buildings to entire cities. It has been commercialized under the name "WiMAX"

4. WWAN… is a form of wireless network, requires differences in technology. Wireless networks of all sizes deliver data in the form of telephone calls, web pages, and streaming video.

Networking Standard

Wireless

1.IEEE802.112.IEEE802.11a3.IEEE802.11b4.IEEE802.11g5.IEEE802.11n

… is a set of media access control (MAC) and physical layer (PHY) specifications for implementing wireless local area network (WLAN). It specified two net bit rates of 1 or 2 megabits per second (Mbit/s)

1. IEEE802.11

… allow transmission and reception of data at rates of 1.5 to 54Mbit/s. It operates in the 5 GHz band, so that its not allow using in Thailand.

2. IEEE802.11a

The 802.11b standard has a maximum raw data rate of 11 Mbit/s. Devices operating in the 2.4 GHz range include microwave ovens, Bluetooth devices, baby monitors, cordless telephones and some amateur radio equipment.

3. IEEE802.11b

Like 802.11b, 802.11g devices suffer interference from other products operating in the 2.4 GHz band, for example wireless keyboards.

4. IEEE802.11g

802.11n is an amendment which improves upon the previous 802.11 standards by adding multiple-input multiple-output antennas (MIMO). It operates at a maximum net data rate from 54 Mbit/s to 600 Mbit/s.

5. IEEE802.11n

Effective Criteria

1. Competency2. Reliability3. Security

1. Competency)1.1 time for data transfers

1.2 amount of user in network

1.3 type of media1.4 Devices

2. Reliability2.1 The frequency of failure in data transmission2.2 The duration of the recovery or system recovery in case of failure.2.3 Prevention to the system failure.

3. Security3.1 Right of access to information 3.2 Threat Protection – Virus computer

Benefit of Network

1. Communication1.1 E-board1.2 E-mail1.3 E-conference1.4 Online conversation – Cha

etc.

2. Data searching… to search for data or information on the WWW, which result of searching be Text, Image, Sound, or Multimedia.

3. Business3.1 Electronic data exchange3.2 Electronic funds transfer3.3 Electronic commerce

4. Education E-learning | E-media | distance learning | blended learning | M-learning

5. Medical Telemedicine | Video telephony | Telenursing | Telepharmacy | Telesurgery | Health information technology

Telemedicine

SDU : IT Services

1. SDU Web Hosting Service

2. Identity Manager | IDM

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3. SDU Kiosk

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4. SDU mailhttps://

sdumail.dusit.ac.th/

SDU : IT Services

5. SDU WIFI

๐ Dusit๐ Dusit Guest๐ Dusit Secure

SDU : IT Services

SDU WIFI

7. WebVPN

SDU : IT Services

http://webvpn.dusit.a

c.th

WebVPN

QUESTION ?