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Copyright © 2005 Heathkit Company, Inc. All rights reserved.
Unit 10
Networks
2
The basic components of a network:
• Connections (Physical Medium)
• Protocols (Common language)
• Services (Clients, Servers, and Files)
3
The Client is the computer requesting the use of a resource.
May I have Worksheet-101?
May I have Worksheet-101?
Client Server
4
The Server is the computer providing the resource.
Sure, here it is!
Sure, here it is!
Worksheet-101Worksheet-101
Client Server
5
In some networks, every computer acts as both Client and Server.
Client &Server
Client &Server
Client &Server
6
Peer-to-Peer Network
Client &Server
Client &Server
Client &Server
7
Peer-to-Peer Network
• No centralized data access.
• Security handled by assigning each resource a password.
8
Peer-to-peer works best with a a small number of computers.
9
One computer can act as server for several clients.
Server
Client
Client
Client Client
Client
Client
10
Client/Server Network
• Centralized data access.
• Centralized security.
• Centralized administration, record keeping, and control.
11
Larger networks require the client/server arrangement.
12
The Physical Medium is the channel the data travels
between computers.
Physical MediumPhysical Medium
Client Server
13
The Physical Media can be:
• Wire
• Fiber Optic Cable
• Wireless Link (RF or Infrared)
• Hardware devices such as network cards, hubs, routers, etc.
14
The common language is the Network Protocol.
May I have Worksheet-101?
May I have Worksheet-101?
Client Server
Sure, here it is!
Sure, here it is!
15
Protocol
• A signed document containing the record of the points on which agreement has been reached by negotiating parties.
• The code of ceremonial forms and courtesies accepted as proper and correct in official dealings.
16
In Networking, Protocols are:
• Agreements that describe how things work.
• Industry-wide frameworks that describe every aspect of communications between computers.
• Grouped together into Protocol Suites.
17
The main Protocol Suites:
• NetBEUI – Small Microsoft networks.
• SPX/IPX – Primarily Novell networks.
• TCP/IP – Must be used if the network is to connect to the Internet.
18
One of the most basic ways to classify networks
is by their topology.
19
Topology refers to the way the computers in the network are connected to
each other.
20
The most common topologies are:
• Bus
• Star
• Ring
• Mesh
21
Bus Topology
“T”“T” “Backbone”“Backbone”
22
Bus Topology• A single cable interconnects all workstations.
• The cable is terminated at both ends.
Terminator
Terminator Terminator
Terminator
23
Star Topology
24
Star Topology
All workstations connect to a single central hub.
Hub
25
Ring Topology
26
Ring Topology• Backbone is a ring.
• Each workstation connects only to two other workstations.
27
Mesh Topology
28
Mesh Topology
Router Router
Router Router
Net-1
Net-4 Net-3
Net-2
29
The Internet is an example of a Mesh topology.
InternetInternet
30
Another way of classifying networks is
by their size or geographical span.
31
The most common size classifications are the:
• Local Area Network (LAN)
• Metropolitan Area Network (MAN)
• Wide Area Network (WAN)
32
The Local Area Network The Local Area Network (LAN)(LAN)
33
Metropolitan Area Network(MAN)
34
Wide Area Network
WANWAN
Copyright © 2005 Heathkit Company, Inc. All rights reserved.
Networking Components
36
Components
• Network Operating System
• Interface Cards
• Cables
37
Network Operating System (NOS)
vs. desktop Operating System
(OS)
38
NOS provides improved security
• User-level Security
• Server authenticates:– User name– User password– User location
• Server determines which resources the user may access.
• Simplifies security for the user.
39
The NOS allows sensitive resources to be maintained in a
centralized/secure location.
40
The NOS provides improved performance.
• Client is relieved of the burden of server
• Server can be optimized
• Adds administration and management capabilities.
41
The NOS provides better administration.
• Centralized security
• Centralized data
• Consistent policies
• Administrative tools
• Accountability
42
The NOS allows scalability• The client/server network grows gracefully.
• A server may handle over 50 clients.
• Additional servers can be added.
• Specialized servers– File server– Print server– Communications Server
43
Disadvantages of the NOS
• More expensive
• More complex
• Requires administration.
44
Major Network Operating Systems
• Unix
• Novell NetWare
• Windows NT Server
45
Unix
• Multitasking, Multi-user OS
• Influential in evolution of the Internet
• Uses TCP/IP
• Clients communicate with Server using Terminal Emulation
46
Linux• Smaller, easier to use version of Unix
• Easily adapted to individual computers or as server in a small network
• Uses the command line as the user interface.
• Offered with a graphical user interface.
47
Novell’s NetWare
• Text-based operating system
• Supports all Windows-based client computer operating systems
• IPX/SPX is the primary NetWare protocol
48
Windows NT
• 32-bit network operating system
• First to use a graphical user interface
• Not as feature-rich as Unix and NetWare
• Supports a wide range of network clients
49
The Network Interface Card is also called:
• The Network Card
• The Network Adapter
• The Network Adapter Card
• The NIC
50
The NIC is the main interface between the computer and the
network cable.
51
Parallel data into serial data.
CPUMemory
Computer
NIC
1001100110011001
Cable
1-0-0-1-1-0-0-1
52
Considerations when selecting the NIC:
• Type of cable connection
• Type of Address/Data Bus
• The method used to configure the card.
53
The NIC must match the cable.
RJ-45RJ-45
BNCBNC
54
RJ-45 ConnectorRJ-45 Connector
55
The NIC must match the Address/Data Bus of the computer.
ISAISA
PCIPCI
56
Installing the NIC in the computer.
• NIC installed inside the computer.
• Normally plugs into a bus slot.
• Some are built right into the motherboard.
• Plug-in boards must be configured correctly.
57
NIC Configuration Methods
• Plug-and-Play
• EEPROM
• Jumper pins
58
Preparing to Install the NIC
• Ensure there is an open bus slot.
• Ensure the adapter is compatible.
• Ensure there are system resources available.
• Ensure all installation items are available.
• Ensure all software is available.
59
Installing the NIC Hardware
• Configure the NIC to available resources.
• Use a ground strap.
• Remove cover from the computer.
• Remove rear panel slot cover plate.
• Remove card from its antistatic bag and immediately plug it into motherboard.
• Secure card slot cover plate to computer.
60
Installing the NIC Software
• Loading the device driver used by the NIC.
• Loading any utilities supplied with the NIC.
61
NIC Device Driver
• Supports communication between the NIC and OS.
• Automatically installed and configured if both NIC and OS support PnP.
• In other cases, driver loaded from floppy or CD supplied with NIC.
62
A more recent device driver may be available
at the website of the NIC manufacturer.
63
Troubleshooting the NIC
• Is NIC talking to the motherboard?
• Is the NIC working internally?
• Is the NIC communicating with the external network?
64
LEDs
LinkLink
ActivityActivity
65
Twisted-Pair Cable
• UTP—Unshielded Twisted-Pair
• STP—Shielded Twisted-Pair
66
Twisted-Pair Cable
STPSTP STPSTPUTPUTP
FoilShield
FoilShield Wire
BraidShield
WireBraidShield
FoilShield
FoilShield
67
10BaseT Ethernet uses Unshielded Twisted Pair
(UTP) cable.
68
RJ-45 ConnectorRJ-45 Connector
Strain Relief CrimpStrain Relief Crimp
ContactsContacts
LatchLatch
WiresWires
69
Twisted-Pair Advantages• UTP is inexpensive.
• Workstations isolated from each other by central hub.
• Easy to add workstations to segment.
• Easier to route than coaxial cable.
• Easier to troubleshoot than coaxial cable network.
70
Twisted-Pair Disadvantages• UTP cable is susceptible to RFI/EMI.
• Suffers crosstalk between wire pairs.
• Poor conductor; attenuates signal more quickly than coax.
• Maximum segment length half of coax.
• STP cable more expensive than UTP cable or coax.
• Difficult to work with shielding.
71
EIA/TIA Cable Categories
• Category 1—Voice-grade UTP phone
• Category 2—Data-grade UTP, 4 Mbps
• Category 3—Data-grade UTP, 10 Mbps
• Category 4—Data-grade UTP, 16 Mbps
• Category 5—Data-grade UTP, 100 Mbps
72
Category 3 Cable
• Common data-grade cable.
• Four unshielded twisted-pair wires.
• Transmission rates up to 10 Mbps.
73
Category 5 Cable
• Data-grade cable.
• Official transmission rates up to 100 Mbps.
• Four unshielded twisted-pair wires.
74
Two Bus Technologies:
• 10Base5 or Thicknet
• 10Base2 or Thinnet
75
Coaxial Cable Characteristics
Sleeve Wire Braid Dielectric Center Conductor
FoilRG-8 Thicknet Cable
RG-58 Thinnet Cable
76
Coax Advantages
• Resistant to RFI.
• Good conductor.
• Longer network segments.
• Thinnet: easy/inexpensive workstation interconnection.
• Thicknet: stronger, more durable than any other network cable.
77
Coax Disadvantages• Each segment must be terminated.
• Break in cable disables entire segment.
• Difficult to add workstations to a thinnet segment.
• Thicknet: difficult to use, heavy shield braid and foil.
• Thicknet: requires special piercing tap and transceiver.
78
What’s in a name?
• 10Base5
• 10Base2
79
The number on the left is the speed of the LAN.
10 Base 5
10 Base 2
Speed inMegabits
Per Second
Speed inMegabits
Per Second
80
The number on the right is the length of the LAN segment.
10 Base 5
10 Base 2
Length ofSegment
in Hundreds Of Meters
Length ofSegment
in Hundreds Of Meters
81
The word in the middle signifies the type of signal.
10 Base 5
10 Base 2
Type of Signal
82
BasebandBaseband
BroadbandBroadbandSignal 1
Signal 2
Signal 3
83
RG-58, 10Base2, or Thinnet CableRG-58, 10Base2, or Thinnet Cable
RG-8, 10Base5, or Thicknet CableRG-8, 10Base5, or Thicknet Cable
84
The RG-58’s lighter shield still provides good protection against electrical noise.
85
Fiber Optic CablesFiber Optic Cables
86
Cable Construction
87
Fiber end-view
88
The Glass FiberThe Glass Fiber
89
ST connector
90
ST Connector
Copyright © 2005 Heathkit Company, Inc. All rights reserved.
LAN Communication
92
LAN Technologies:
• Ethernet
• Token Ring
• ARCnet
• LocalTalk
93
Ethernet• Developed by Xerox in early ’70s.
• Has become most popular networking technology in use today.
• A variety of speeds and cabling options have evolved.
• It is fast, inexpensive, and flexible.
• It continues to evolve.
• Majority of new networks use Ethernet.
94
Networking is all about sending data from one
location to another.
May I have Worksheet-101?
May I have Worksheet-101? Sure, here
it is!
Sure, here it is!
PC-1 PC-2
95
The CPU routinely sends data from one place to
another.
CPU
96
But when multiple computers are involved, a
new series of problems arise.
PC-1 PC-2 PC-3 PC-4 PC-5
97
How do you keep all the computers from transmitting
at the same time?
PC-1 PC-2 PC-3 PC-4 PC-5
98
Is this for me?
Is this for me?
PC-1 PC-2 PC-3 PC-4 PC-5
99
Who sent this?
Who sent this?
PC-1 PC-2 PC-3 PC-4 PC-5
100
PC-1 PC-2 PC-3 PC-4 PC-5
Ah, it’s from PC-1. Gee, I wonder if it is correct.
101
PC-1 PC-2 PC-3 PC-4 PC-5
Here’s the ten gigabyte folder
you wanted!
Here’s the ten gigabyte folder
you wanted!
102
Large files are broken into manageable chunks called packets.
Large File
Packets
103
How do you keep two computers from transmitting
at the same time?
PC-1 PC-2 PC-3 PC-4 PC-5
104
Carrier SenseMultiple Access/
Collision Detection(CSMA/CD)
105
Carrier Sense
• Each computer attached to the network examines the cable before transmitting.
• If it senses traffic on the cable, it waits until the traffic clears before transmitting.
106
Multiple Access
• All computers on the network have equal access to the cable.
• A lowly desktop has the same access as the Windows NT Server.
• Access is on a first-come, first-served basis.
• The only consideration is: “Is someone else using the cable?”
107
Collisions still happen
PC-1 PC-2 PC-3 PC-4 PC-5
108
The computers involved in the collision detect the
collision.
PC-1 PC-2 PC-3 PC-4 PC-5
Wow! That’s not what I
said!
Wow! That’s not what I
said!
Wow! That’s not what I
said!
Wow! That’s not what I
said!
109
The computers involved in the collision back off for a random
length of time.
PC-1 PC-2 PC-3 PC-4 PC-5
I’ll back off for “x”MicrosecondsI’ll back off for
“x”Microseconds
I’ll try “y” Microseconds.
I’ll try “y” Microseconds.
110
Collisions are a natural characteristic of Ethernet.
PC-1 PC-2 PC-3 PC-4 PC-5