6. Twisted Pair Cabling
Twisted pair is a transmission medium
consisting of two insulated wires that are
twisted together to create a double helix
that reduces noise levels and eliminates
crosstalk between the wires.
Unshielded twisted pair (UTP)
Shielded twisted pair (STP) has an
extra layer of insulation
7. Twisted Pair Cabling
Twisted-pair cabling is broken into categories.
CAT 5 means category 5.
The wires terminate in an RJ-45 connector.
8. Coaxial Cabling
Coaxial cable, also known as coax, consists of a
cylindrically braided outer conductor that surrounds and
shields a single solid inner copper wire conductor.
9. Coaxial Cabling
Coaxial cable comes in two forms:
Thinnet Thicknet
Thin coaxial cable Thick coaxial cable
Used in 10Base2 Used in 10Base5
Ethernet networks Ethernet networks
Cable segments up to Cable segments up to
185 meters in length 500 meters in length
10. Fiber Optic Cabling
Fiber optics is a transmission method
that transmits light-modulated video,
voice, or data signals through hair-thin
strands of glass called fibers.
These strands are encased by a layer of
Kevlar-reinforced reflective material called
cladding, which keeps the light inside the fiber.
12. Wireless Media
Includes cellular, radio, microwave,
satellite, and infrared signals.
Network nodes that use wireless
connections must have a wireless NIC,
which connects to a transceiver known as
a wireless access point (WAP).
Defined by the 802.11 standards.
For more information, go to
www.microsoft.com/windowsxp/mediacenter
23. Computer Network
is a system of data terminal equipment
(Exp.mainframe system, workstation,
PC’s, terminals, other device) which
communication with one another over
media(Exp.electronic conductor, fibre
optic conductor) and are linked together
by transmission equipment(modems,
multiplexer) or subnetworks
(LAN’s,MAN’s,WAN’s)
25. Characteristics of a Network
All networks require:
A physical connection (or wireless connection).
A set of communication rules called protocols.
One or more network services that will receive
the communication.
26. Mainframe/Terminal Model
The mainframe/terminal model
A mainframe is a centralized computer to
which users connect to obtain network
services.
The terminal is a
device with a keyboard, which you
use to type commands or enter data to
communicate with the mainframe
computer.
27. Client-Server Model
Client-server refers to the manner in
which computers exchange information
by sending it (as servers) and receiving
it (as clients).
Computers can serve dual roles as both
servers and clients.
28. Multi-Tier
Large organizations may subdivide complex applications
into multiple stages called tiers.
Multi-tier computing typically includes three tiers
consisting of the user interface tier, the business tier, and
the database tier.
31. การเชื่อมตอแบบ LAN
แบง การออกแบบเปน 2 วิธี
Server Based : แต ล ะ Workstation
พึ่ ง พา Central Computer ที่ จะให บริการ
File, Printing
Peer-to-peer (P2P) is a network
architecture in which each workstation
has equal responsibilities.
32. รูป แบบก ารเชื่ อมต อ Network แบบ Server Based
LAN Workstation
Harddisk IBM PS/2 IBM PS/2 IBM PS/2 IBM PS/2
Mainframe
Gateway
File Server Print Server
Modem
IBM printer
IBM PS/2 IBM PS/2 IBM PS/2
Printer Communication
Server
34. Network Topologies
A network’s geographical shape is referred to as
the network’s topology.
The five kinds of network topologies are:
Bus topology
Ring topology
Star topology
Hybrid topology
Mesh topology
35. Bus Topology
The bus topology has a single cable, called
the bus or the trunk, to which every device
on the network connects.
All of the messages on the bus pass by each
device, or node, on the bus.
It uses inexpensive coaxial cable that is
easy to install.
A break anywhere along the cable causes all
network traffic to stop.
36. Ring Topology
A ring topology forms when you connect a network’s
nodes in a circle.
Messages flow in a single direction.
A small packet called a token circulates the ring – a
device must have the token to use
the network.
37. Star Topology
In a star topology, each
device in the network
connects to
a central hub, which
distributes messages from
one node to another.
Provides centralized
control
Easy expansion
Fault tolerance
38. Hybrid Topology
A hybrid topology in a network employs more than one
topology to connect devices.
39. Mesh Topology
In a mesh
topology, multiple
connections are
made.
In mission-critical
operations, you want
as much redundancy
as possible so that
if one part of the
network goes down,
the packets can find
an alternate path to
their destination.
40. ขอดีของ PC local Network
การใชอปกรณตาง ๆ รวมกัน (Device Sharing)
ุ
การใช ไฟล หรือ โปรแกรม รวมกัน (Shared File Access)
การสื่อสารภายในองคกร (Communication Within
Organization)
การนําเอาโปรแกรมใหม ๆ มาใชงานไดงายขึ้น
การจัดการบริหารที่งายขึ้น (Management)
42. What is a Server
A Server คือ Computer ที่ ใ ห บริก าร
Computer ตัวอื่ นบนเครือ ข าย ชนิดของ
Server ส วนใหญใ น เครือ ข าย คื อ File
Server และ Print Server
43. ชนิด ของ Server
File Server
Print Server
Communication Server
Database Servers
44. ข อ ดี Server Based
เร็ว การทํางานบน Server จะทําไดเร็วกวา การทํางานแบบ
Peer-to-Peer
Full Featured
มีมาตรฐานอุตสาหกรรม
สนับสนุนการทํางานกับเครือขายใหญ ๆ
การรักษาความปลอดภัยของขอมูลทําไดดีกวา
45. ข อ เสีย Server Based
ราคาคอนขางแพง
การติดตั้งระบบทําไดยาก
จําเปนตองคนดูแลระบบ
46. ข อ ดี Peer to Peer
ราคาไมแพง
การติดตั้งทําไดงาย
การใชงานทําไดงาย
ไมจําเปนจะตองมี Stand-alone server
48. Network Operating System
A network operating system is the
software that adds to a computer the
functions required for connecting
computers together for networking.
Microsoft Windows (peer to peer)
Windows 2003, Windows NT
UNIX and Linux
Mac OS
Novell NetWare
49. Microsoft Windows
Microsoft Windows is the most wide
spread network operating system.
Every version of Windows contains networking
capability, but some versions
do not support all network services.
For a history of Windows server products,
visit
www.microsoft.com/windows/winhistoryserver.
mspx
50. UNIX and Linux
The UNIX and Linux operating systems
support the full range of networking
services, including both client- and server-
side components.
The Open Group holds the trademark and
defines the official version of UNIX at
www.unix-systems.org
Linux is an open source version of UNIX
To learn more, go to www.linux.org
51. Mac OS
The Macintosh OS X operating system
has networking built in.
Behind the Macintosh user interface is
a UNIX-based operating system.
To learn more, go to
www.apple.com/macosx/features/unix
52. Novell NetWare
NetWare is a PC-based local area
networking product that was one of the
most dominant network operating systems
during the decade following its invention
in 1983.
However, when Microsoft marketed Windows
NT
in 1993, Novell NetWare’s market share
dropped.
For more information, go to
www.novell.com/products/netware
53. หนา ที่ พ้ื นฐานของ Network
Operating System
File Server
Print Service
Back up
Security
54. Extending Network
WAN (Wide Area Network)
MAN (Metropolitan area Network)
Internetworks
Big LANs
55. MAN
A metropolitan area network
(MAN) connects local networks
across a larger geographical region.
The term metropolitan implies that
MANs cover an area the size of a city.
56. WAN
A wide area network (WAN) uses
high-speed transmission lines to
connect MANs and LANs over large
geographical areas.
58. Network Components
A repeater interconnects two network
cables so they can be treated as a single
cable.
Allows one to extend the length of the cable.
A switch filters, forwards, and floods
frames based on the destination MAC
address of each frame.
To flood is to pass traffic out all of the switch’s
connections except for the incoming interface
through which the traffic was received.
59. Network Components
A bridge is used to connect two network
segments and pass packets between them
based on the destination MAC address of
each frame.
A switch is a multiport bridge.
A router forwards network traffic along
the optimal path based on information in
the packet’s Network Layer header.
60. Bridges
LAN LAN
Desktop System Desktop System Desktop System Desktop System
Bridge Bridge
Desktop System Desktop System
Bridge Bridge
61. Routers
Desktop System Desktop System Desktop System Desktop System
Router
Router
Desktop System Desktop System
Router
Desktop System Desktop System
Desktop System
62. Network Components
A bridge router (brouter) is a relay that
functions as both a router and a bridge.
A gateway is a computer that routes
traffic from a workstation on an internal
network to an external network such as
the Internet.
63. Gateway
Desktop System Desktop System Desktop System Desktop System
GATEWAY GATEWAY
Desktop System Desktop System
GATEWAY GATEWAY
Desktop System Desktop System
Desktop System Desktop System Desktop System Desktop System
64. Protocol
A protocol is a set of rules that define
how computers communicate with each
other.
The International Standards Organization
(ISO) developed an international standard
called the Open System Interconnection
(OSI) Reference Model (OSI/RM).
65. OSI Reference Model
This model comprises of seven layers that
describe the way data is shared on a
network.
Suppose you just clicked on a link on a
Web page. The following slides describe
the process from one layer to another.
Data is passed down from Layer 7 to Layer 1,
is then transmitted over the medium, and then
goes back up from Layer 1 to Layer 7 in the
receiving device.
Headers are added at each layer.
66. Layer 7: Application
Through an Application Programming
Interface (API), the browser informs the
Application Layer of your request.
The Application Layer begins to form the
packet that will eventually travel across
the network.
67. Layer 6: Presentation
The Presentation Layer translates the
data into a standard network data format.
It can use data compression to streamline
the packet so it does not consume
unnecessary bandwidth on the network.
It can also encrypt the data for sensitive
data transmissions.
68. Layer 5: Session
The Session Layer negotiates the
connection that will be made between the
two computers exchanging data.
It inserts a checkpoint, which is a marker
used to signal that a certain amount of the
data has arrived all right.
69. Layer 4: Transport
The Transport Layer works to ensure
that the data arrives reliably at its
destination.
If the amount of data is large, the data is
split into fragments that are numbered
sequentially.
70. Layer 3: Network
The Network Layer organizes data into
datagrams consisting of the data
from the Transport Layer and routing
information such as the source and
destination addresses.
71. Layer 2: Datalink
The Data Link Layer transforms the data
into data frames.
It consists of two sublayers:
Logical Link Control (LLC)
Performs error checking and regulates the flow
of data.
Media Access Control (MAC)
Handles the actual placement of the packets
onto the Physical Layer.
72. CRC
The Data Link layer also calculates a
cyclic redundancy check (CRC) based
on the information in the frame.
The receiving machine calculates its own CRC
and compares it to the value in the frame. If
they do not match, the frame is corrupt and
discarded.
73. Layer 1: Physical
The Physical Layer transforms the 0’s
and 1’s into signals that flow over the
transmission media.
At the receiving end, the Physical Layer
converts these signals back into 0’s and
1’s and passes them up to the Data Link
Layer.
