Transcript Unit 10

Unit 10
Networks
Copyright © 2005 Heathkit Company, Inc. All rights reserved.
The basic components
of a network:
• Connections (Physical Medium)
• Protocols (Common language)
• Services (Clients, Servers, and
Files)
2
The Client is the computer
requesting the use of a resource.
May I have
Worksheet-101?
Client
Server
3
The Server is the computer
providing the resource.
Sure, here it
is!
Server
Client
Worksheet-101
4
In some networks, every computer
acts as both Client and Server.
Client &
Server
Client &
Server
Client &
Server
5
Peer-to-Peer Network
Client &
Server
Client &
Server
Client &
Server
6
Peer-to-Peer Network
• No centralized data access.
• Security handled by assigning
each resource a password.
7
Peer-to-peer works best with a a
small number of computers.
8
One computer can act as server
for several clients.
Client
Client
Client
Client
Client
Server
Client
9
Client/Server Network
• Centralized data access.
• Centralized security.
• Centralized administration,
record keeping, and control.
10
Larger networks require the
client/server arrangement.
11
The Physical Medium is the
channel the data travels
between computers.
Client
Server
Physical Medium
12
The Physical Media can be:
• Wire
• Fiber Optic Cable
• Wireless Link (RF or Infrared)
• Hardware devices such as
network cards, hubs, routers, etc.
13
The common language is the
Network Protocol.
May I have
Worksheet-101?
Client
Sure, here it
is!
Server
14
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.
15
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.
16
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.
17
One of the most basic
ways to classify networks
is by their topology.
18
Topology refers to the
way the computers in the
network are connected to
each other.
19
The most common
topologies are:
• Bus
• Star
• Ring
• Mesh
20
Bus Topology
“T”
“Backbone”
21
Bus Topology
• A single cable interconnects all workstations.
• The cable is terminated at both ends.
22
Star Topology
23
Star Topology

All workstations connect to a single central hub.
24
Ring Topology
25
Ring Topology
•
Backbone is a ring.
•
Each workstation connects only to two other
workstations.
26
Mesh Topology
27
Mesh Topology
Net-1
Net-4
Net-2
Net-3
28
The Internet is an example of a Mesh
topology.
Internet
29
Another way of
classifying networks is
by their size or
geographical span.
30
The most common size
classifications are the:
• Local Area Network (LAN)
• Metropolitan Area Network
(MAN)
• Wide Area Network (WAN)
31
The Local Area Network
(LAN)
32
Metropolitan Area Network
(MAN)
33
Wide Area Network
WAN
34
Networking
Components
Copyright © 2005 Heathkit Company, Inc. All rights reserved.
Components
• Network Operating System
• Interface Cards
• Cables
36
Network Operating System
(NOS)
vs.
desktop Operating System
(OS)
37
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.
38
The NOS allows sensitive
resources to be maintained in a
centralized/secure location.
39
The NOS provides
improved performance.
• Client is relieved of the burden
of server
• Server can be optimized
• Adds administration and
management capabilities.
40
The NOS provides
better administration.
• Centralized security
• Centralized data
• Consistent policies
• Administrative tools
• Accountability
41
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
42
Disadvantages of the NOS
• More expensive
• More complex
• Requires administration.
43
Major Network
Operating Systems
•
Unix
•
Novell NetWare
•
Windows NT Server
44
Unix
•
Multitasking, Multi-user OS
•
Influential in evolution of the Internet
•
Uses TCP/IP
•
Clients communicate with Server using
Terminal Emulation
45
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.
46
Novell’s NetWare
•
Text-based operating system
•
Supports all Windows-based
client computer operating systems
•
IPX/SPX is the primary NetWare
protocol
47
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
48
The Network Interface
Card is also called:
• The Network Card
• The Network Adapter
• The Network Adapter Card
• The NIC
49
The NIC is the main interface
between the computer and the
network cable.
50
Parallel data into serial data.
Memory
CPU
Computer
10011001
Cable
1-0-0-1-1-0-0-1
NIC
51
Considerations when
selecting the NIC:
• Type of cable connection
• Type of Address/Data Bus
• The method used to configure the
card.
52
The NIC must match the cable.
RJ-45
BNC
53
RJ-45 Connector
54
The NIC must match the
Address/Data Bus of the computer.
ISA
PCI
55
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.
56
NIC Configuration Methods
• Plug-and-Play
• EEPROM
• Jumper pins
57
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.
58
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.
59
Installing the NIC Software
• Loading the device driver used
by the NIC.
• Loading any utilities supplied
with the NIC.
60
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.
61
A more recent device
driver may be available
at the website of the NIC
manufacturer.
62
Troubleshooting the NIC
• Is NIC talking to the
motherboard?
• Is the NIC working internally?
• Is the NIC communicating with
the external network?
63
LEDs
Link
Activity
64
Twisted-Pair Cable
• UTP—Unshielded Twisted-Pair
• STP—Shielded Twisted-Pair
65
Twisted-Pair Cable
Foil
Shield
Foil
Shield
STP
UTP
Wire
Braid
Shield
STP
66
10BaseT Ethernet uses
Unshielded Twisted Pair
(UTP) cable.
67
RJ-45 Connector
Strain Relief Crimp
Contacts
Wires
Latch
68
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.
69
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.
70
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
71
Category 3 Cable
• Common data-grade cable.
• Four unshielded twisted-pair
wires.
• Transmission rates up to 10 Mbps.
72
Category 5 Cable
• Data-grade cable.
• Official transmission rates up to
100 Mbps.
• Four unshielded twisted-pair wires.
73
Two Bus Technologies:
• 10Base5 or Thicknet
• 10Base2 or Thinnet
74
Coaxial Cable Characteristics
RG-58 Thinnet Cable
Sleeve
Wire Braid
Dielectric
Center Conductor
RG-8 Thicknet Cable Foil
75
Coax Advantages
• Resistant to RFI.
• Good conductor.
• Longer network segments.
• Thinnet: easy/inexpensive
workstation interconnection.
• Thicknet: stronger, more durable
than any other network cable.
76
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.
77
What’s in a name?
• 10Base5
• 10Base2
78
The number on the left is
the speed of the LAN.
10 Base 5
Speed in
Megabits
Per Second
10 Base 2
79
The number on the right is the
length of the LAN segment.
10 Base 5
Length of
Segment
in Hundreds
Of Meters
10 Base 2
80
The word in the middle
signifies the type of signal.
10 Base 5
Type of Signal
10 Base 2
81
Baseband
Signal 1
Signal 2
Broadband
Signal 3
82
RG-8, 10Base5, or Thicknet Cable
RG-58, 10Base2, or Thinnet Cable
83
The RG-58’s lighter shield still
provides good protection
against electrical noise.
84
Fiber Optic Cables
85
Cable Construction
86
Fiber end-view
87
The Glass Fiber
88
ST connector
89
ST Connector
90
LAN
Communication
Copyright © 2005 Heathkit Company, Inc. All rights reserved.
LAN Technologies:
• Ethernet
• Token Ring
• ARCnet
• LocalTalk
92
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.
93
Networking is all about
sending data from one
location to another.
May I have
Worksheet-101?
PC-1
Sure, here
it is!
PC-2
94
The CPU routinely sends
data from one place to
another.
CPU
95
But when multiple
computers are involved, a
new series of problems arise.
PC-1
PC-2
PC-3
PC-4
PC-5
96
How do you keep all the
computers from transmitting
at the same time?
PC-1
PC-2
PC-3
PC-4
PC-5
97
Is this for
me?
PC-1
PC-2
PC-3
PC-4
PC-5
98
Who sent
this?
PC-1
PC-2
PC-3
PC-4
PC-5
99
Ah, it’s from PC-1.
Gee, I wonder if it is correct.
PC-1
PC-2
PC-3
PC-4
PC-5
100
Here’s the ten
gigabyte folder
you wanted!
PC-1
PC-2
PC-3
PC-4
PC-5
101
Large files are broken into
manageable chunks called packets.
Large File
Packets
102
How do you keep two
computers from transmitting
at the same time?
PC-1
PC-2
PC-3
PC-4
PC-5
103
Carrier Sense
Multiple Access/
Collision Detection
(CSMA/CD)
104
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.
105
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?”
106
Collisions still happen
PC-1
PC-2
PC-3
PC-4
PC-5
107
The computers involved
in the collision detect the
collision.
Wow! That’s
not what I
said!
Wow! That’s
not what I
said!
PC-1
PC-2
PC-3
PC-4
PC-5
108
The computers involved in the
collision back off for a random
length of time.
I’ll try “y”
Microseconds.
I’ll back off for
“x”Microseconds
PC-1
PC-2
PC-3
PC-4
PC-5
109
Collisions are a natural
characteristic of Ethernet.
PC-1
PC-2
PC-3
PC-4
PC-5
110