CTS1131_Mod6_1Networkingx

pigeoneggtrainsNetworking and Communications

Oct 24, 2013 (3 years and 9 months ago)

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Module 6

Networking

Why Network?

Despite the
costs of implementation and
maintenance
, networks actually save
organizations money by allowing them to:


Consolidate (centralize) data storage


Share peripheral devices like printers


Increase internal and external communications


Increase productivity and collaboration

Networking

A

network

is a group of
computers that
can share
information through their interconnections
.

1.
Computers

(nodes or hosts).

2.
T
ransmission media
provides
a path for electrical signals
between devices.

3.
Network interfaces

are devices that send and receive
electrical signals.

4.
Protocols

are rules or standards that describe how hosts
communicate and exchange data
.

Networking

Network
Type

Description

Peer
-
to
-
peer

In

peer
-
to
-
peer

networking (also called

workgroups
), each computer
controls access to its own resources. Security controls on each
computer identify who can have access to the computer's resources.

Client/server


In

client/server

networking, shared resources reside on special
computers called

servers
. Other computers, called

clients

connect to
the server to access resources. Security controls on the server identify
which clients can have resource access.


Windows computers use the concept of a

domain

for client/server
networking. The domain identifies a group of computers with the
same security and administrative boundaries.
Active Directory
is a
service that provides a centralized database of resources within a
domain.

Protocols

A

protocol

is a rule that identifies some aspect of how computers
communicate on a network.
For two computers to communicate, they
must be using the same
protocols.


Protocols are grouped into
protocol

suites
, or sets of related
protocols
.


Virtually
all operating systems today provide native (built
-
in)
support for TCP/IP.


Most older versions of some operating systems used a different
protocol as the default protocol suite. For example, older NetWare
servers used IPX/SPX, while Mac OS systems used AppleTalk.


Older operating systems without native TCP/IP support enabled TCP/IP
communications by either installing the protocol stack or through a
process known as

encapsulation

or

tunneling
. With this process, non
-
TCP/IP packets are re
-
packaged as TCP/IP packets at the sending
device. The receiving device strips off the TCP/IP headers to reveal the
original packets.


Protocols

Protocol

Description

HTTP

HyperText

Transfer Protocol is
used by Web browsers and Web servers to
exchange files
(Web
pages) through the World Wide Web and
intranets.


HTTP can be described as an information requesting and
responding protocol.

HTML

HyperText

Markup Language is
a data format that is used to create
hypertext documents that can be viewed from multiple platforms.

HTML has
become a common language used for programming information
in a format that is readable by web browsers.

DNS

Domain Name System is
a system that is distributed throughout the
Internet
to provide
Host name/IP address

resolution
. For example, the
name

www.mydomain.com

would be identified with a specific IP address.

Protocols

Protocol

Description

Telnet

Remote Terminal Emulation allows
an attached computer to act as a
dumb terminal, with data processing taking place on the TCP/IP host
computer.

SSH

Secure Shell allows
for secure interactive control of remote systems.

SSH
is a secure and acceptable alternative to Telnet.

SSL

Secure Sockets Layer secures
messages being transmitted on the Internet.
It uses RSA for authentication and encryption.
Web
browsers use SSL
(Secure Sockets Layer) to ensure safe Web transactions.

URLs
that begin with

https://

trigger your Web browser to use SSL.

HTTPS

HyperText

Transfer Protocol over Secure Socket Layer or HTTP over SSL.
HTTPS
is a secure form of HTTP that uses SSL as a
sublayer

for security.

Addressing

Network devices use addresses to identify other devices. These
addresses are used to send and receive packets of electronic data over
the network. The addresses used depend on the physical make
-
up of
the network as well as the protocol suite being used
.

Each
network device is identified using
a:


physical address or MAC
(like a serial number)


logical network

address
(subnet) identifies a network segment.


All devices on the same network segment share the same logical
network address.


logical

host

address
(name) identifies a specific host on the
network.


Each device must have a unique logical host address.

Physical Addressing
(MAC)

Each network device is identified using a physical address.
Ethernet networks use a
MAC Address
(physical device address)


The MAC address is a
unique

hexadecimal identifier burned into the
ROM (physically assigned address) of every network interface.


When you change the network card, the host will have a new physical
device address.


When you move a device to another network, the physical address
remains the same (as long as the network card has not been changed).


The MAC address is guaranteed unique through design.


The first half (first 6 digits) of the MAC address is assigned to each
manufacturer.


The manufacturer determines the rest of the address, assigning a
unique value which identifies the host address.


Logical Network Address

With
TCP/IP, the logical network and logical host addresses are
combined into a single address called the
IP
address
.


An IP address is
a 32
-
bit binary number represented as four octets (four 8
-
bit
numbers). Each octet is separated by a period.


A

subnet mask

is used to differentiate the network and host addresses.


Each IP address has a default class that includes a default subnet mask value.
The

class

defines the default network address portion of the IP address.


For
example, an IP address of 192.168.6.11
with a default
mask of 255.255.255.0.
The network address is 192.168.6.0 and the host address is 11.


Instead of using the default subnet mask, you can use custom subnet masks to
define different network addresses. This process is called

subnetting
.


Note
: The address range from 0.0.0.0 to 0.255.255.255 is reserved for broadcast
messages to the current network. The address range from 127.0.0.0 to
127.255.255.255 is reserved for loopback addresses to the local host.



Logical Host Address


Humans remember names (or hostnames) much easier than
numbers (especially binary numbers).


A hostname is a label (name) assigned to a device connected
to a computer network
.


Hostnames
are used to identify the device in a Domain Name
System (DNS) such as the World Wide Web.


Hostnames
that include DNS domains are often stored in the
Domain Name System together with the IP addresses of the
host they represent for the purpose of mapping the hostname
to an address, or the reverse process
.

Networking
Devices

Component

Description

Media

The networking

medium


is the pathway for
signals to pass between two
devices.


Copper cables use electrical signals.


Fiber optic cables use light pulses.


Wireless networks use radio waves with the air being the transmission medium.

Network
adapter

A

network adapter

creates the signals that are sent along the networking
medium.


The term network interface card (NIC) typically describes an adapter that uses a
cable medium (such as copper or fiber optic cables).


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Networking Devices

Component

Description

Hub

A

hub

provides a central connection for multiple media
segments on the same subnet.


The
hub repeats a signal received on one port out all other
ports.


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-
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Bridge

A

bridge

connects two segments within the same subnet that
use different media types. For example, use a bridge to
connect wireless clients to wired clients on the same
network.

Networking Devices

Component

Description

Switch

A

switch

provides a central connection for multiple media
segments on the same subnet.


The
switch receives a signal on one port, and forwards that signal only
to the port where the destination device is connected
.


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Networking Devices

Component

Description

Router

A

router

connects two network segments that have a different
subnet
addresses.


A
router has multiple network connections, with each connection
being on a different subnet.


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Networking Standards

Method

Description

Ethernet

Ethernet is the most common local area networking standard for wired networks.

Ethernet can use copper and fiber optic cables
. Ethernet
uses network interface
cards, hubs, switches, and routers to connect devices.

Wireless

Wireless networking uses radio waves for sending network data within a local area
network
. An
access point with an integrated router allows wireless clients to
communicate with hosts on different networks (such as the Internet).

Dialup

A dialup connection uses a modem connected to the phone line to communicate with
another host through a wide area connection.


Dialup connections are available anywhere a dialup telephone line exists.


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Networking
Standards

Method

Description


(DSL)

Digital Subscriber Line provides broadband digital data transmission over existing
telephone lines. A DSL router (sometimes called a DSL modem) connects the computer to
the telephone line.
DSL
is not available to every location; the end location must be within
a fixed distance of telephone switching equipment.

Cable

Cable networking uses a cable TV connection to create a wide area connection to the
Internet
. A
cable modem (router) connects the computer to the cable network for
sending networking signals.

Cellular

Cellular networking uses a digital mobile phone for Internet access
. Mobile
phones with
digital data plans use cellular calls to connect to the Internet
. You
can install a cellular
adapter in a notebook computer to provide cellular access.

Satellite

Satellite networking uses radio signals sent and received from a satellite
. Requires
direct
line of sight (dish placement is crucial
). Is
subject to mild atmospheric and weather
conditions (fog or slight wind can disrupt service
). Provides
nearly 100% global coverage.

Coaxial
Cable

Coaxial cable is an older technology that is
usually implemented with a bus topology.

Advantages


Highly
resistant to Electromagnetic Interference (EMI)


Highly resistant to physical damage

Disadvantages


Expensive


Inflexible construction (difficult to install)


Unsupported by newer networking standards


Twisted Pair cable

Twisted
pair cables support a wide variety of
fast, modern
network standards

Advantages


Inexpensive
compared to other media types


Easy to install and manage


Very common (media and tools are easy to obtain)

Disadvantages


Most
susceptible to EMI of all the media types


Cables are more easily damaged than other
types

Fiber Optic Cable

With fiber optic cabling the plastic or glass core
carries the signal.

Advantages


Totally immune to Electromagnetic Interference (EMI)


Highly resistant to eavesdropping


Supports extremely high data transmission rates


Allows greater cable distances without a repeater

Disadvantages


Very expensive


Difficult to work with and requires special training