Chapter Objectives
• Describe the status of information
communication past and present
• List the factors that led to the growth of
computer communications
• Outline a few sample communication
applications
• Discuss the evolution of Wide Area
Network communications and its current
convergence to digital technology
Communication in the Past
• Known as Data Communications
– Mostly concerned with alphanumeric
data
• A highly specialized topic
• Focus
– Mainframes
– Analog telecommunication technology
– WANs
Communications at
Present
• Known as Information Communication
– Data, image, audio and video
communications
• A necessary topic for IT professionals
• Focus
– Microcomputers
– Digital communication technology
– LANs, WANs etc.
• Internet
– Internet, Intranet and Extranet
Data and Information
Communication
Data
Computer
Data
Information
Image
Audio
Video
Real-time streaming
Audio and Video
Transmission
• Requirements
– More bandwidth is required
– Real-time transmission may also be
required
• Solution
– Compression
– Streaming
• Note: Streaming includes
compression as well
Comparison of Data and
information Communication
Data and Information
Communications
Data Communications
Alphanumeric data
Mainframe focused
Analog technology
Specialized topic
Private network based
WANs
Information
Communications
Data, image, audio
and video
Microcomputer
focused
Digital technology
General topic
Internet based
LANs and WANs
Key Words
•
•
•
•
•
Mainframe
Centralized
Analog
Data
Telecommunicatio
n network
•
•
•
•
•
LANs
Distributed
Digital
Information
Computer
network (Internet)
Homework
• Difference between Internet,
Intranet, Extranet
• Explore Godaddy and other hosting
services
• Download, install and experiment
with Microsoft Encoder and Audacity
– Convert between different audio file
formats
Opportunities in
Communications
• Specialized knowledge is required for
specialist in the communication field
– Example: Network Engineer
– Certification examinations are available for
attesting to the special skills
• Some knowledge of communications is
required of all in the computer field
Certification
• Microsoft Certification
– MCSA & MCSE
• CISCO Certification etc.
• Network+ Certification
• Different vendors offer certifications at
different levels of expertise
– Contact their web sites for further information
Certification Websites
• Microsoft
– http://www.microsoft.com/learning/mcp
/certifications.mspx
• Internet
• Fast access technologies for the Internet
ramp
• Emergence of microcomputers as a serious
business and home computing tool and the
focus on connectivity
• Move from large mainframe based
infrastructure to LAN based structures
• Client-server computing architectures
• Emerging concept of terminal servers
Growth Factors Continued
• Home networking
• Digitization of telecommunication lines
• Wireless networking
• Multimedia on the Internet
• Internet security
• Virtual Private Network
• Voice over IP (VoIP)
Homework
• Fast access technologies
– DSL, Cable, T1, T3, OC1, OC2
– Home fiber connections
• IBM business computers
– Replacements for mainframes
Evolution
• Physical architecture
– From mainframes to LAN based
• Functional architecture
– Centralized mainframe based architecture to
LAN based client-server architecture
– In the case of LAN based architecture, clientserver evolved following the initial
introduction of the peer-to-peer network
architecture
– Client-server architecture is now followed by
terminal server architecture
Early Mainframe-based
Centralized Architecture
External Analog
Lines
Mainframe
MiniComputer
Term.
Front End Processor
Modem
Server
Concentrator
Term.
Term.
Distributed LAN Based
Architecture
LAN
Mainframe/
Minicomputer
Systems
External Digital/
Analog Lines
Fiber Optic Backbone
(FDDI) or Switched Network
Connectivity
Modem
Gateway
LAN
WAN (Internet)
Gateway
(TCP/IP)
Current Trend in
Distributed Architecture
Source:
CISCO
Major Components of the
Distributed Architecture
•
•
•
•
•
•
•
•
Clients
Servers
Network interface cards
Cables (copper and fiber)
Switches
Routers
Internet ramps
Internet
Key Words
•
•
•
•
Mainframe based
Centralized
Distributed
Fiber ring
• Fiber switches
End of Module
Homework
• Explore some of the Catalyst
switches at Cisco
Network Architectural
Evolution
• Mainframe
• LAN
– Peer-to-Peer
– Client Server
• File server
• Application server
• Terminal server
Peer-to-Peer Networking
• Initial architecture of the LAN prior
to client-server architecture
• Each client operates on equal
footing in sharing resources
• Unlike the client-server
architecture, there is no server on
the network in peer-to-peer
networking
P2P Sharing
• Basic sharing is supported
– Files
– Printers
– Internet connection
• Large scale sharing of databases
and other business applications
are not included in P2P sharing
Client-Server Evolution
• Client-server architecture is always
identified by the presence of a server
• The evolution of client-server can be
traced to three sub-architectures that
are based on the functional feature of
the server
– File server
– Application server
– Terminal server
Preview of File Server
Computing
Back-end data storage.
Server
Clients
Front-end computing
All the processing of the application is done at the client.
Preview of Application
Server
ack-end data storage and local retrieval
of data.
Computing
Server
Clients
Front-end interface and data manipulation tools.
Application processing is shared between the client and
the server.
A Preview of Terminal
Server Computing
Powerful
Terminal
Server
Extensive back-end data
storage, retrieval and
Processing
Thin Clients
Front end processing limited to terminal operations
Factors Used in the
Comparison of Architectures
• Point of execution of applications
• Network traffic
• Security
• Hardware/Software requirements
• Total Cost of Ownership (TCO)
Path of Evolution
More power to the user
Peer-to Peer
Distributed
Network
Centralized
Mainframe
Terminal
Server
Application
Server
File Server
Reduced cost of ownershipBetter management of shared dat
Homework
• Browse for wiring closet, RJ-45
patch cables, wiring rack, punch
block etc.
Digitization Of Telecom
Network
• Initial telecom network was based on
analog technology
– Copper wire
– Electronic transmission
– Coaxial cables and twisted pair cables
• Current telecom
– Copper wires and fibers
– Electronic and optical transmission
– Fiber cables and twisted pair cables
Digital WAN Carrier
Technologies
• DSL
• ISDN
• T1, T3 etc.
• OC1, OC3 etc.
WAN Communication
Technologies
• FDDI and CDDI
• Frame Relay
• Asynchronous Transfer Mode (ATM)
Voice Transmission
• Past is based on analog technology
• Currently, it is moving to digital
technology
– VoIP
Access Speeds
• Fastest speed of an analog modem is
around 56K bps
• Newer and mostly digital access
technologies such as DSL can operate at
faster speeds
– Download speed is usually in Mbps
– Upload speed is in Kbps
• ADSL and SDSL
– In SDSL both upload and download
speeds are the same
Typical DSL Speed
• Upload
– 128K bps
• Download
– 1.3M bps
Some DSL Providers
• Covad
– http://
www.covad.com/products/access/
dsl.shtml
• SBC
– http://www02.sbc.com/DSL/
• DSL Extreme
Testing the Access Speed
• The current bandwidth of a
connection can be tested by
accessing websites that test the
connection speed
– www.dslreports.com
– www.2wire.com
Access Security
• www.grc.com
Summary of Access
Technologies
for
the
s
s
t
e
c
c
Internet
re Ac
i
DN
D
e
t
Sa
Telecommuting
Terminal Services
Satellite
Office
PSN
Home
Terminal Services
Terminal Server
Main Office
Telecommuting Options
• Employer supported
– Previous example falls into this category
where the employer provides access to the
office computer from home
– Example: Terminal services
• User initiated
– Gain access to one’s computer in the
office
– A remote control software is required
– Examples: XP Remote Desktop and
GoToMyPC
Some Communication
Software
• Hyper Terminal
• Telnet
• FTP
• Procomm Plus
• Remote Desktop
Homework
• Dlink home network router
• Linksys home network router
• Enterprise
– Campus LANs and organizational LANs
• Advanced
– WANs such as an Internet based Virtual
Private Networks (VPNs)
Typical Wired LAN
Client OS
Client 1
Switch
Windows
2000/2003,
Linux
Windows XP/Vista; Linux
Client 2
Server:
Network OS,
Applications,
Data etc.
Client 3
Server Operating
System
Typical Wireless LAN
Client OS
Client 1
Windows XP/Vista; Linux
Client 2
Client 3
Wireless NIC
Wireless Access
Point
Server:
Network OS,
Applications,
Data etc.
Windows
2000/2003
Server,
Linux
Some LAN Applications
•
•
•
•
•
•
Share business applications
Share data
Share printers, modems etc.
Share the Internet and Internet resources
Send electronic-mail
Engage in audio/video streaming and
conferencing
• Act as the infrastructure for the .net or J2EE
architecture
Network Security
• Network security is an important
issue given the fact that many
computers are connected to the
Internet using broadband
connections
General Security Threats
• Viruses
• Denial of service attack
• OS vulnerabilities
• E-mail vulnerabilities
• Macro execution vulnerabilities
• Ect.
General Security Measures
• Anti-virus
• Anti-spyware
• Anti-spam software
• Firewalls
– Both software firewalls and hardware
firewalls can be installed
Secure Communications
• Cryptography
– Encryption
• Virtual Private Network (VPN)
• IPSec and other secure protocols
• Digital signatures
Examples of Protocols for
Secure VPN
• PPTP
• IPSec with encryption
• IPSec with L2TP
• SSL with encryption
Examples of Protocols for
Trusted VPN
• MPLS with constrained distribution
of routing information through BGP
("layer 3 VPNs")
• Transport of layer 2 frames over
MPLS ("layer 2 VPNs")
(Source:
http://www.vpnc.org/vpn-standards.
html
)
WAN: The Early Days
• Telecommunication needs
– Centered on analog technology
• Data communication needs
– Centered around digital technology
• Digital to analog interface
– For long distance computer
communications
Long-distance
Communications
Modulation
Interface
Digital
Digital
Analog
Plain Old Telephone Service (POTS)
Initial WANs
• Overcome the limitations of general
purpose analog telephone lines
• Better conditioned lines such as leased
lines were used on the network segment
• Driven by a collection of computers to
route the data traffic from its source to
its destination
• Arpanet was the first WAN that was
created
A Summary of the Basic
Components of the WAN
Routing devices
Leased lines
Computers/
Routing algorithms
Present Status of WANs
• Information is carried in digitized
form
• Digital communication lines
– Over copper wire
– Over fiber-optics
• Digital merger
– Telecommunications
– Computer communications
WANs: Present and Future
• Fully digital
• Technologies
– Frame Relay
– ATM
• Point-to-point digital
communication will become the
norm
Emerging WAN
ATM Switches
ATM operating at several
hundred Mbps
Digital
Ramp
Business
Computer
System
Point-to-point ATM connection may become
possible?
ATM Possibility
Internet Backbone
Client 1
Client 2
1 Gbps
25 Mbps
300 Mbps
Server
100 Mbps
ISP
Likely Scenario
• Ethernet on the desktop
• Possibly, ATM on the backbone
Ethernet Challenge
Client 1
Client 2
10 Gbps
1 Gbps
(Gigabit)
Hub
ISP
10 Mbps/
100 Mbps/
1 Gbps/
Server
10 Gbps
100 Mbps
(Fast)
10 Mbps
1 Mbps
(Past)
Current Ethernet Speeds
• 1G bps used widely
• 10G bps is gradually gaining
grounds
• 100G bps is on the horizon
Net Result
• At the local level (LAN) Ethernet
will remain the technology of
choice for the foreseeable future
• At the WAN level, ATM will
dominate over other WAN
technologies
The Digital Future: Fusion
• Digital fusion
– Computing
– Telecommunications
• Use of computers and the Internet
in all forms of communications that
would include data as well as all
forms of media
– An example is Voice over IP (VoIP)
Possible Scenario
• IP based universal digital
communication over the Internet
with IP addresses as the point of
identification
– Data, voice and video communication
will be done over the Internet
Voice Over IP (VoIP)
• VoIP is the digital replacement for
the traditional analog phone line
• VoIP is based on the Internet
– It is packet switched as opposed to
the traditional phone service that is
circuit switched
Voice Over IP Growth
• Growth of VoIP is fuelled by the economy
of using the Internet and the technological
advantage of the digital technology
• It signifies the inevitable use of digital
technology and the Internet to carry voice
• VoIP is poised to grow and probably
become the de facto public voice carrier
technology
VoIP Challenges
• Latency inherent to the IPv4
protocol
• Availability of bandwidth
VoIP Remedies
• Newer protocol such as IPv6 is
designed to address latency
• Faster Internet backbones such as
those using Optical Carrier (OC)
lines and ATM transport
technologies are being introduced
to increase the bandwidth of the
communication lines
Long Term Developments
• Indications are that residential
connections in the long term would
evolve into Internet connections
replacing the phone connection
Business and Residential End
Points
• Instead of identifying an end point
in a business or a residence with a
phone number, it is plausible that
the end point could be identified
with a number similar to an IP
address
VoIP Application: Broadband
Phone
• Broadband phone may be touted
as the first real sign of
convergence between computer
and telephone networks
• VoIP application in the form of
broadband phone will also
contribute to the growth of
communication on the Internet
Broadband Phone
• Uses a DSL or cable modem
connection
• Sample vendor
– Vonnage
• Broadband phone is known as an
Internet appliance
Emergence of Internet
Appliances
• Internet appliances are devices that
can be used without explicit
programming
• The software code necessary will be
stored in firmware in the appliances
• Functionalities of the appliances
could well be chosen with the use of
buttons that may resemble the
buttons on a telephone dial pad
Internet Appliances
• A broad range of Internet appliances will
then become available for residential
use with the broadband phone featuring
prominently as perhaps the most used
Internet appliance
• Other Internet appliances may include
Radios, Interactive TV, Evolving Palm
Pilots etc.