Transcript Brian Kovar - Kansas State University

Data
Communications
Networking and Telecommunications
topics for the Business Student
What is the difference between
telecommunications and a network?
• TELECOMMUNICATIONS - the
over public or private networks
of
• NETWORK – t
connected together using
/protocols so that they can work together.
What are the benefits of a network?
1. The ability to
with others
is the most popular form of network communications
2. The ability to share
D
Peripheral devices and other resources
Software
Processing power
What is the most basic way to
differentiate networks? By
• L
Network (LAN) --Connects
computers in relatively
• W
Networks (WAN)
-- Connects computers dispersed
among a number of buildings, or
even in different cities.
Biggest WAN =
• P
Network (PAN)
--Wirelessly connecting small
personal devices, really
Wireless Topology
• Computers are connected by
a wireless
(which is directly
connected to a wired LAN)
to
– Must be within a certain number of feet from the access
point to
communicate
wirelessly
(35-300 feet
depending on
the technology
being used)
Comparing Wired to Wireless
Wired Network
Wireless Network
• Communications occur using • Communication occurs using
a wired media.
signals and base station. Limited by
obstructions.
• F
• Tends to be more
• L
and hard to
move around (bound to the
wire). Limited by walls,
furniture, infrastructure.
• Should be able to easily
handle multiple users
• F
• S
: rarely reaches max
speeds that could be available
•
Inherently
: security features not
turned on: easier to have data packets
captured.
• M
. Relatively easy to connect to.
Must be within range of hotspot (base station)
•
work
• All of the work tools that you •
need probably are available
One person could monopolize the base
station with huge data transfers: slowness for
everyone.
Computer can be
, but work
tools needed may not be available when
needed.
Bluetooth vs Wi-Fi (802.11)
• Business networks use
(Wi-Fi/Wireless Fidelity) while
individuals might create their own
network
using B
Bluetooth
• Allows for wireless communications within a
: 2 megabits per second, up to 30 feet.
• Less expensive than Wi-Fi chips,
, easier to build
into small devices than run on batteries such as cell phones, palmtop computers, and other PDAs.
• Called a “personal area network” (PAN) technology.
802.11
802.11b
Provides transmission speeds of up to 11 mbps, 300 feet inside, 800 feet outside.
802.11g
Provides transmission speeds of up to
802.11a
Uses a
radio frequency than standards b & g and other electronic devices
(kinda like taking a less crowded route: it will be faster since no one is using it)
802.11n
Still being developed: expected to provide transmission speeds over
using MIMO technology (
mbps, at a
indoor
mbps
):
Walt Mossberg Chief Technology columnist for the
WallStreet Journal
Q: I’m wondering about wireless specs for a
laptop. I suspect the “n” version of Wi-Fi is best
but “g” is adequate. Any advice would be
appreciated.
A. It depends on how and where you intend to use
your laptop’s wireless connectivity. The “n”
version of Wi-Fi can be much faster than “g” and
can have much greater range. However, the speed
difference won’t matter much if your sole use is
connecting to the Internet with a typical home or
public hotspot service, since the maximum speed
of these services is almost always well below “g”
and “n” capabilities. But if you are streaming
video at home or backing up large files wirelessly
among computers and networked hard disks on a
home network, you’d be much better off with “n,”
assuming all devices involved support it. The
same goes for range. In a small apartment, it likely
won’t matter. In a large home, it could.
802.11 wireless standards explained
http://compnetworking.about.com/cs/wireless80211/a/aa80211standard.htm
http://info.cba.ksu.edu/bkovar/wireless.htm
802.11 standards
• 802.11b: can provide transmission speeds of up to 11 mbps,
300 feet inside, 800 feet outside.
• 802.11g: can provide transmission speeds of up to 54 mbps,
at a 35 foot indoor range.
• Both the “b” and “g” standards use the same radio
frequency, or wavelength.
– 802.11a: same transmission speeds as the “g” standard, but it uses
a different radio frequency (not used by other Wi-Fi users,
microwave ovens and cordless phones)
• Good for use in high density/population areas, such as apartment complexes.
• 802.11n is currently being developed (in use, but not finalized) .
– Expected to provide transmission speeds over 100 mbps using MIMO
technology (multiple wireless signals and antennas): signal intensity will also
help increase range.
What are Protocols and what is the
difference between them?
• Protocol - a
as well as the
that specifies the
during transmission
• Following a certain
for interoperability
, allows
– Interoperability - the capability of two or more computer
systems to share data and resources, even though they are
made by different manufacturers
• Two primary communications protocols are TCP/IP
and Ethernet
– TCP/IP is used for
– Ethernet is used by computers in a
to communicate
Ethernet
• Ethernet - a physical and data layer
technology for LAN networking
Ethernet
• Defines the
LAN.
standards used in a
• Used to describe the
–
–
–
–
W
(Co-axial, twisted-pair, fiber-optic)
How bits are physically transmitted using those media
Access control rules
Data transmission speeds
• Details
principle of
and works on the
and
• Helps insure the compatibility of different devices so that
many people can attach to a common cable.
Transmission Control Protocol/
Internet Protocol
• Transmission Control Protocol/Internet
Protocol (TCP/IP) - provides the technical
as well as
for large numbers of private network
• The TCP/IP protocol suite is made up of over
protocols.
– The two
– TCP provides for
– IP provides the
mechanism
are TCP and IP
TRANSMISSION CONTROL
PROTOCOL / INTERNET PROTOCOL
(TCP / IP)
• Allows computers to
their
regardless of
or hardware.
• Transmission Control Protocol
– Breaks information into data packets
– Reassembles packets when received
– Checks for lost packets
• Internet Protocol
– Each computer given a unique IP address
– Used to
– 209.1.144.212
TCP/IP’s four-layer reference model
• The
– F
– Simple
layer allows users and applications to access
protocol (FTP)
protocol (SMTP)
– T
provides terminal emulation that allows a “
terminal with
” to be able to connect to a
host computer (which will control everything).
– H
protocol (HTTP)
– Simple network management Protocol (SNMP)
TCP/IP’s four-layer reference model
• The
• The
• The
layer handles
layer handles the packets (
, etc.)
layer details how
through the networking
is
How Does the Internet Work??
http://www.howstuffworks.com/web-server.htm
#1
#2 Browser communicates with
209.1.144.212
to get
#3 Browser
connects to
specific server,
uses GET request
to ask for file you
wish to see.
#4 Server sends
HTML text to
your browser.
HTML tags are
read and page
displayed.
What is a VPN?
• You can build your own
wired network or you
can
from a
national provider.
• Virtual private network
(VPN) - a way to use the
telecommunication
infrastructure (e.g.,
) to provide secure
access to an organization’s network
–T
software is used to create a
connection between two different servers (
).
– Data packets are
Network Data Transfer Process: How does it happen?
• Network operating system at the source divides the message to be sent
into segments of predetermined length called
• Network operating system at the source uses a communications
protocol to
• Network Operating System at the source sends packets over the
network.
• Packets are routed as necessary through the network depending on the
transmission mediums, transmission signal characteristics and access
control methods.
• Network Operating system at the destination receives packets over the
network.
• Network Operating system at the destination
by looking at the
communication protocol information. Requests retransmission of any
missing data.
Connecting
Networks
LAN
The connection between a LAN and a larger
network is usually accomplished using a
device called a
. Routers are used to
. They also
“sit”
(serving as a gatekeeper both into and out of your
network). They are intelligent connecting
devices that examine each packet of data it
receives and then decides which way to send it
onward toward its destination
WAN or Backbone
Router
LAN
Routers are responsible
for
that
messages take from the sending
computer to the destination computer.
Router
Wide Area Network
P
Packet Switched Network
Data is packaged in
for transmission. R
R
R
R
R
R
R
R
R
R
R
R
Each packet follows
through
the network.
R
occurs when the
sending computer
divides a message
into a number of
efficiently sized
units called
packets, each of
which contains
the address of the
destination
computer.
Once a network is linked
to a
, it
becomes part of the
Internet community.
Backbone is
usually a type
of network that has
WANs
High Speed Backbone
Internet Backbone on the Ocean Floor
What are the
different types of
LANs?
P
Each user can share a
portion their
computer’s
with other LAN users
C
Only resources on
specific computers called
“servers”
can be shared
Peer-to-Peer Networks
• Peer-to-peer (P2P)
network - any
network without a
central file server
and in which all
computers in the
network have
access to the public
files located on all
other workstations
Client/Server Networks
• Client - a computer that is designed to
from a server
• Server - a computer that is dedicated to providing
information in response to external requests
• Client/server network - model for applications in
which the
takes place on a
, while the
is handled by the
The Client/Server Model
Data Management
Storage and management of the data
needed by the application
Actual business rules implemented
Business Logic
The
Presentation
to the application
Client/Server Model: A Business
View
The different Client/server implementations differ
according to:
1. Where the processing for the
2. Where the processing of
3. Where the
(DBMS) and
occurs
are located
Flexible Applications
Server
Client
Data Management
Business
Presentation
Logic
Business Logic
Presentation
Any Combination is Possible
Client
Data Management
Business Logic
Design Server
Presentation
Data Management
Business Logic
Production Server
Client/Server Advantages
• Application can be structured to match organizational
requirements since it is both
– Can change the implementation of this model as the organization
changes in size since the Client/Server model provides the
to whatever
is
• Data access is
regardless of where the data is stored.
• Separate programs are more easily maintained and can be
reused.
• One
easier to
for all of the
and
Client/Server Disadvantages
• All shared resources reside on computers
call “servers”
– If a disaster occurs on the server all the data is in
jeopardy
– If the server malfunctions,
• Expensive
– Usually require expensive hardware and extra staff to
manage
– Only
of client/server costs are tied up in
– The remaining
is in the form of
IT professionals and knowledge workers.
- both
Current Events in
Information Technology
Researchers explore scrapping and
rebuilding the Internet
• In order to address the problems that were not
envisioned when the Internet was initially created,
some are suggesting rebuilding the Internet using a
approach.
• S
– The Internet was designed to be open and flexible and all
users were assumed to be trustworthy. Internet protocols
were not designed to authenticate users and their data.
Firewalls and spam filters are now being used to control
security.
– Solution: data not passed along until
• Mobility
– Initially, computers were fixed in location so IP addresses were assigned to
devices in a fixed location. Wireless mobile computing is presenting challenges
related to data flow.
– Solution: R
so that addresses are based on the device,
rather than the location.
• Ubiquity (also called Pervasive Computing)
– When the Internet was first designed, there were relatively few computers
connected to it. The addressing system has become strained due to the
proliferation of personal computers and mobile devices.
– Solution: assign
and have those same
devices connected to an addressed gateway, which is then connected to routers
and the rest of the Internet
• Result is fewer devices to keep track of and improved efficiency.
• These changes may happen over the next 10-15 years. They
(expected to cost
as computer hardware and software and Internet
infrastructure are replaced)