Transcript บทที่ 3 - Suan Dusit Rajabhat University

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
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.
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. Simplex
2. Half-Duplex
3. Full-Duplex
Communication
Direction
1. Simplex
communication 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 twoway radio that has a "push-to-talk" button
Communication
Direction
3. Full-Duplex
both parties can communicate to the other
simultaneously. An example of a full-duplex device is
a telephone
Type of Network
1. by flow of data
2. by function of computer
3. by size of service
flow of data
 Centralized Network
flow of data
 Distributed
Network
Function of Comp.
Peer to Peer OR Workgroup
Client Server
Size of Network
 LAN , MAN , WAN
… 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.
Networking Standard
Wire
1. LANs are most likely based on Ethernet
technology, Token Ring, FDDI
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.
1.2 Token-Ring
… is a protocol which resides at the data link
layer (DLL) of the OSI model. It used a special threebyte 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 as
IR (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.IEEE802.11
2.IEEE802.11a
3.IEEE802.11b
4.IEEE802.11g
5.IEEE802.11n
1. IEEE802.11
… 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)
2. IEEE802.11a
… 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.
3. IEEE802.11b
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.
4. IEEE802.11g
Like 802.11b, 802.11g devices suffer interference
from other products operating in the 2.4 GHz band,
for example wireless keyboards.
5. IEEE802.11n
802.11n is an amendment which improves upon
the previous 802.11 standards by adding multipleinput multiple-output antennas (MIMO). It operates
at a maximum net data rate from 54 Mbit/s to 600
Mbit/s.
Effective Criteria
1. Competency
2. Reliability
3. Security
1. Competency)
1.1 time for data transfers
1.2 amount of user in network
1.3 type of media
1.4 Devices
2. Reliability
2.1 The frequency of failure in data transmission
2.2 The duration of the recovery or system
recovery in case of failure.
2.3 Prevention to the system failure.
3. Security
3.1 Right of access to information
3.2 Threat Protection – Virus computer
Benefit of Network
1. Communication
1.1 E-board
1.2 E-mail
1.3 E-conference
1.4 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. Business
3.1 Electronic data exchange
3.2 Electronic funds transfer
3.3 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
SDU : IT Services
2. Identity Manager | IDM
SDU : IT Services
3. SDU Kiosk
SDU : IT Services
4. SDU mail
https://sdumail.dusit.ac.th/
SDU : IT Services
5. SDU WIFI
๐ Dusit
๐ Dusit Guest
๐ Dusit Secure
SDU WIFI
SDU : IT Services
7. WebVPN
http://webvpn.dusit.ac.th
WebVPN
QUESTION ?