Transcript Linux+ Guide to Linux Certification

NETWORKING FUNDAMENTALS
Network+ Guide to Networks, 4e
2
Why Use Networks?
• Network: group of computers and other devices
that are connected by some type of transmission
media
• Advantages of using networks over standalone
computers:
– Networks enable multiple users to share the
network’s resources (devices and data)
– Networks allow you to manage, or administer,
resources on multiple computers from a central
location
Network+ Guide to Networks, 4e
3
NETWORK ARCHITECTURE
Peer-to-peer Networks
• Every computer can communicate directly with
every other computer
• By default, no computer has more authority than
another
• Every computer is capable of sending and
receiving information to and from every other
computer
Network+ Guide to Networks, 4e
4
Peer-to-peer Networks
Figure 1-1: Resource sharing on a simple peer-to-peer network
Network+ Guide to Networks, 4e
5
Client/Server Networks
• Server: central computer used to facilitate
communication and resource sharing between
other computers on the network (called clients)
• Client/server network: uses a server to enable
clients to share data, data storage space, and
devices
• To function as a server, a computer must be
running a network operating system (NOS)
Network+ Guide to Networks, 4e
6
Client/Server Networks (continued)
Figure 1-2: Resource sharing on a client/server network
Network+ Guide to Networks, 4e
7
Client/Server Networks (continued)
• Advantages of using client/server networks over
peer-to-peer networks:
– User logon accounts and passwords can be
assigned in one place
– Access to multiple shared resources can be centrally
granted to a single user or groups of users
– Problems can be tracked, diagnosed, and often fixed
from one location
Network+ Guide to Networks, 4e
8
Client/Server Networks (continued)
• Advantages of using client/server networks over
peer-to-peer networks (continued):
– Servers are optimized to handle heavy processing
loads and dedicated to handling requests from
clients, enabling faster response time
– Because of their efficient processing and larger disk
storage, servers can connect more than a handful of
computers on a network
Network+ Guide to Networks, 4e
9
TYPES OF NETWORKS
• Local area network (LAN): confined to a relatively
small space, such as a building or an office
• Metropolitan area network (MAN): larger than a
LAN; connects clients and servers from multiple
buildings
• Wide area network (WAN): connects two or more
geographically distinct LANs or MANs
Network+ Guide to Networks, 4e
10
LANs, MANs, and WANs (continued)
Figure 1-4: A simple WAN
Network+ Guide to Networks, 4e
11
BENEFITS OF A NETWORK
• Information sharing: Authorized users can use other
computers on the network to access and share information
and data. This could include special group projects,
databases, etc.
• Hardware sharing: One device connected to a network, such
as a printer or scanner, can be shared by many users.
• Software sharing: Instead of purchasing and installing a
software program on each computer, it can be installed on the
server. All of the users can then access the program from a
single location.
• Collaborative environment: Users can work together on
group projects by combining the power and capabilities of
diverse equipment.
Network+ Guide to Networks, 4e
12
HOW ARE NETWORKS
CATEGORIZED?
• Networks are usually classified using three
properties:
• Topology
• Protocol
• Architecture
Network+ Guide to Networks, 4e
13
NETWORK
TOPOLOGIES
• Network Topology (or layout) – refers to the way
computers and peripherals are configured to form
networks
– Bus topology – all computers are linked by a single
line of cable
– Star topology – multiple computers and peripheral
devices are linked to a central computer, called a
host
– Ring topology – each computer or workstation is
connected to two other computers, with the entire
network forming a circle
– Hybrid topology – combine network layout
types to meet their needs
Network+ Guide to Networks, 4e
14
NETWORK/COMMUNICATION
PROTOCOLS
• A protocol is simply an agreed-on set of rules
and procedures for transmitting data between
two or more devices.
• Features determined by the protocol are:
– How the sending device indicates it has finished
sending the message.
– How the receiving device indicates it has received
the message.
– The type of error checking to be used.
Network+ Guide to Networks, 4e
15
Signals and Protocols
• A data network is a group of computers connected
by a network medium.
• The network medium carries signals between
computers.
• Signals reduce complex information to the simplest
possible form.
• Computers communicate by using a language
called a protocol.
Network+ Guide to Networks, 4e
16
Protocol Services
•
•
•
•
•
•
•
Packet acknowledgment
Segmentation
Flow control
Error detection
Error correction
Data compression
Data encryption
Network+ Guide to Networks, 4e
17
The OSI Reference Model
Network+ Guide to Networks, 4e
18
Data Encapsulation
Network+ Guide to Networks, 4e
19
The OSI Reference Model
Network+ Guide to Networks, 4e
20
NETWORKING HARDWARE AND
SOFTWARE
• Hub – electronic device (with a number of ports) used in a LAN to
link groups of computers
• Repeaters (also called amplifiers) – electronic devices that receive
signals and amplify and send them along the network
• Routers - electronic devices used to ensure messages are sent to
their intended destinations
• Gateway – consists of hardware and/or software that allows
communications between dissimilar networks
• Bridge – consists of hardware and/or software
that allows communication between two
similar networks
Network+ Guide to Networks, 4e
21
REPEATERS
•
A common problem in the networking world is that of weakening electrical
signals. Electrical signals traveling through wires (such as copper wires
used in most networks) This effect limits the lengths of the cable that can
be used. when there is a need to connect two computers at a larger
distance.
•
A repeater is connected to two cable segments. Any electrical signal
reaching the repeater from one segment, will be amplified and
retransmitted to the other segment.
An illustration of a repeater at work
The electrical signal entering the repeater at one end is
weakened.The repeater amplifies the electrical signals and
resends the data.
22
ROUTERS
• Routers connect two or more networks and
forward data packets between
them. When data arrives from one of the
segments, the router decides, according to
it's routing table, to which segment to
forward that data.
Network+ Guide to Networks, 4e
23
MODEMS
• An illustration of data sent using a modem and a
regular telephone line.
• A modem is
a device that converts digital data
A modem is a device that converts digital
originatingdata
from
a terminal
computer,
to analog
originating
from or
a terminal
or
signals used
by voice
communication
networks such as
computer,
to analog
signals used by voice
communication
such asmodems
the
the telephone
system. networks
At one end,
convert the
telephone
system. tones
At one end,
digital pulses
to audible
andmodems
convert audio tones
convert the digital pulses to audible tones
back to digital
pulses at the other.
and convert audio tones back to digital
pulses at the other.
24
EXAMPLE OF FIREWALL
Firewalls are systems that establish access control
policies among networks. They can block information
from entering a network or from getting out of that
network, they can permit different users to perform
different kinds of operations, according to the user's
authorizations.
Network+ Guide to Networks, 4e
25
Elements Common to Client/Server
Networks
Network+ Guide to Networks, 4e
26
Elements Common to Client/Server
Networks
Figure 1-8: Examples of network transmission media
Network+ Guide to Networks, 4e
27
How Networks Are Used
• Network services: functions provided by a network
• File services
– Capability of a server to share data files,
applications, and disk storage space
– File server
• Print services: used to share printers across a
network
Network+ Guide to Networks, 4e
28
How Networks Are Used
• Communications services
– Allow remote users to connect to the network
– Remote access server (also known as
communications server or access server)
• Mail services
– Coordinate the storage and transfer of e-mail
between users on a network
– Mail server
Network+ Guide to Networks, 4e
29
How Networks Are Used
• Internet services
– Supplying Web pages, file transfer capabilities,
Internet addressing schemes, security filters, and a
means for directly logging on to other computers on
the Internet
– Web server
• Management services: centrally administer
management tasks on the network
– Traffic monitoring and control
– Load balancing
Network+ Guide to Networks, 4e
30