Transcript Software Architecture

Managing
Telecommunications
Telecom & IS Organization
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IS departments have been responsible for designing,
building, and maintaining the information
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Just as governments are responsible for building and
maintaining streets, roads, and freeways
Telecom provides infrastructure for moving
information and messages
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Internet opened up a new view of telecom of providing a
cyberspace
Telecom History
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Circuit-switching network
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PSTN (POTS)
Suitable for analog voice signals
Overhead of establishing a temporary circuit
(seconds) tolerable
Packet-switching network
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Aimed at transmitting data
Messages are sent in packets
Assume the intelligent user devices
The Evolving Telecommunications Scene
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The Internet can handle all kinds of intelligent
user devices
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The Internet allows these device to handle
different kinds of services
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PDAs, VoIP phones, gaming consoles, wireless
devices, PCs...
Voice, e-mails, graphics, gaming...
The global telecom infrastructure is changing
from a focus on voice to a focus on data
Transformation of Telecom Industry (1)
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The telecom structure of old was originally
provided by (often Government owned)
monopolies (e.g. AT&T)
Gradually, the telecom industry has been
deregulated
Telecom industry is even more competitive than
computer industry
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Bandwidth on fiber is now doubling capacity every four
months
Transformation of Telecom Industry (2)
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The last mile problem for RBOCs in 1990s
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A Fire-hose-to-straw gap
tbps (1012) in backbones VS. 56k or 1.2m in the
last mile (Figure 6-1)
RBOCs then became ILECs, and there came
new competitors CLECs (competitive LECS)
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ILECs bundled local phone access with Internet
access
CLECs came up with new connection options
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Cable modems, optical fiber, wireless, satellite…
Telecom Technologies and Their Speeds
Bits Per Second
Technologies
1011-1012
Optical fiber
1010
Optical wireless local loop(20G), WMAN (100G)
109
Microwave LANs (1.5G-2.0G), Gigabit Ethernet
(1G), WMAN (24g)
108
ATM (155-622M), Faster Ethernet (100M)
107
Frame relay (10M), Ethernet (10M), WLANs(10M),
cable modem (10M), Wi-Fi (11-54M)
106
Stationary 3G (2M), DSL(1.5-7M), WiMax (1.5-10M)
105
Mobile 3G (384k), ISDN (128k)
104
Modems (56k), 2.5G(57k)
103
2G (9.6-14.4k)
Case Example: ICG Communications
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This CLEC provides voice and data services in 25
metropolitan areas in the United States
It was formed in 1984 to provide local telephone
service in Denver.
It expanded to provide long distance, buying up
companies with fiber routes
It later focused on being an Internet backbone
provider, serving ISPs
When the dot-com bubble burst, ICG filed for
bankruptcy, but moved out of bankruptcy in late
2002
Acquired by Level 3 Communication in 2006
The Internet is the Network of Choice (1)
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Internet and telecom surprised us by its fast
rise and fall in the past one decade
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History of the Internet
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In 1960s, APARNET developed by DOD for
transferring scientific files
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Mainly used for email
Until 1993, still an all-text world-wide network for
scientists and academics
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Email, FTP, Telnet, Gopher…
The Internet is the Network of Choice (2)
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In 1994, Tim Berners Lee invented World Wide Web
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URL
HTML
Browser
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The Internet has done for telecom what the IBM
PC did for computing: brought it "to the masses"
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Open architecture of Internet
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Interconnectivity
The Internet is the Network of Choice (3)
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3 important attributes of the Internet
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Ubiquity
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Reliability
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Global reach
Alternate routing, scale-free network
Scalability
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Easy extension of its reach, increasing performance of
websites
The Internet is the Network of Choice (4)
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Intranet
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Internet technology
used inside an
enterprise
Extranet
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Internet technology
used to connect
trading partners,
customers, suppliers
etc.
Public Website
Extranet
E
Intranet
Digital Convergence
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Intertwining of various forms of media –
voice, data and video
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All forms of media can be digitized, put into
packets and sent over an IP network
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Media managed and manipulated digitally and
integrated in highly imaginative ways
IP Telephony (1)
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The use of Internet to transmit voice to replace
their telephone system
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A phone with an IP address, voice delivered in digital
packets
Previously conceived application of IP telephony
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To another IP phone on the LAN
Through the company's WAN to a distant IP phone on
another of the company's LANs
Through an IP voice gateway to the PSTN to a
standard telephone
IP Telephony (2)
IP Telephony (3)
IP Telephony (4)
Video Telephony
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Similar story to IP Telephony
Not video conferencing via a PBX, but rather
video over IP
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With the appropriate IP infrastructure, video
telephony can be, say, launched from an instantmessaging conversation
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IP phones with cameras also facilitate it, phone to phone
IPTV
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IPTV is television content that, instead of being
delivered through traditional broadcast and cable
formats, is received by the viewer through IP
networks.
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Standards used: MPEG2, MPEG4/H.264, MPEG2-TS IP,
UDP, RTP, TCP, etc.
Voice
Video
IP
Converged services
over copper or fiber
Data
Content
Provider
Service
Provider
Delivery
Network
Home
Network
OSI Reference Model
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Closed VS. open network
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Closed network: using proprietary networking
technology
Open network: based on national or international
standards
What is a reference model?
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A division of functionality together with data flow
between the pieces
No detailed standards specified for each layer
An Analogy: Mailing a Letter
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Information encapsulated
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Control information on the envelop
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Address, services
Each layer wraps the message with its own
layer of control information
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Envelop vs. packet
Headers
Reversed unwrap at the receiving end
Seven Layers
Important protocols
7
Application Layer
HTTP
6
Presentation Layer
NetBIOS
5
Session Layer
SSL
4
Transport Layer
TCP
3
Network Layer
IP, X.25
2
Data Link Layer
Ethernet, Token ring, FDDI,
ISDN, ATM, Frame relay
Physical Layer
10BaseT, twisted pair, fiberoptic cable
1
The Physical Layer
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Responsibility:
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Transmission of raw bits over a communication
channel.
Issues:
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Mechanical and electrical interfaces
Time per bit
Distances
The Data Link Layer
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Responsibility:
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Data Link Control sub-layer: provide an errorfree communication link
MAC sub-layer: provides DLC with “virtual
wires” on multiaccess networks.
Issues:
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framing (dividing data into chunks)
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header & trailer bits
addressing
10110110101
01100010011
10110000001
The Network Layer
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Responsibilities:
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Path selection between end-systems (routing).
Subnet flow control.
Fragmentation & reassembly
Translation between different network types.
Issues:
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Packet headers
Virtual circuits
The Transport Layer
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Responsibilities:
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Provides virtual end-to-end links between peer
processes.
End-to-end flow control
Issues:
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Headers
Error detection
Reliable communication
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The Session Layer
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The Presentation Layer
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Establishes, manages, and terminates sessions
between applications.
Data encryption, data compression, data
conversion
The Application Layer
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Anything not provided by any of the other layers
Connecting Network
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Repeater:
physical layer
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Bridge:
data link layer
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Router:
network layer
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Gateway:
network layer and above.
Repeater
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Copies bits from one network to another
Does not look at any bits
Allows the extension of a network beyond
physical length limitations
REPEATER
Bridge
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Copies frames from one network to
another
Can operate selectively - does not copy all
frames (must look at data-link headers).
Extends the network beyond physical
length limitations.
BRIDGE
Router
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Copies packets from one network to another.
Makes decisions about what route a packet
should take (looks at network headers).
ROUTER
Gateway
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Operates as a router
Data conversions above the network layer.
Conversions:
encapsulation - use an intermediate network
translation - connect different application protocols
encrpyption - could be done by a gateway
The Optical Era Will Provide Bandwidth
Abundance
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Decline in cost of key factors
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During the industrial era: horsepower
Since the 1960s: semiconductors
Now: bandwidth
40 million miles of fiber optic cable have been laid
around the world, in the USA at a rate of 4,000 miles
per day
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Half of the cable is dark, that is, it is not used. And the
other half is used to just one-millionth of its potential
Over the next decade, bandwidth will expand ten times as
fast as computer power and completely transform the
economy
The Wireless Century Begins
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The goal of wireless is to do everything we can
do on wired networks, but without the wire
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Wireless communications have been with us for
some time
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Mobile (cell) phones, pagers, VSATs, infrared
networks, wireless LANs etc.
Radio waves are none-deterministic
The 20th century was the Wire-line Century, the
21st will be the Wireless Century
Licensed VS. Unlicensed Frequencies
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Some frequencies of the radio spectrum are
licensed by governments for specific
purposes; others are not
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Devices that tap unlicensed frequencies are
cheaper
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No big licensing fees
Greater competition, more innovation and faster
changes
Possibility of collision between signals
"Telecoms Crash"
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Auctions of the 3g radio spectrum in Germany and Britain at the
beginning of 2000.
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The nature of the auctions, was to offer a limited number of
licenses
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Although one similar auction in the USA had failed disastrously the year
before.
3G also requires an infrastructure development measured in billions of
dollars
This put the telephone operators in a difficult position, as diabetics being
forced to bid for insulin.
The stock market lost confidence (dot-com crash), influencing the
credit rating of the operators
Within a year 100,000 jobs were lost in telecoms in Europe
(30,000 in UK)
Subsequent government auctions of the 3g spectrum were met
with low bids
Wireless Networks (1)
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Wireless Personal Area Networks (WPANs)
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Wireless Local Area Networks (WLANs)
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Provide access to corporate computers in office buildings,
retail stores, or hospitals or access to Internet "hot spots"
where people congregate
Wireless Metropolitan Area Networks (WMANs)
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Provide high-speed connections between devices that are
up to 30 feet apart
Provide connections in cities and campuses at distances
up to 30 miles
Wireless Wide Area Networks (WWANs)
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Provide broadband wireless connections over thousands of
miles
Wireless Networks (2)
Wireless Long Distance (1)
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The only two wireless
technologies are infrared
light and radio airwaves
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Cell phone and cellular
network
1G cellular
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Using analog technology and
circuit switching
Main targeted at voice
service
In the main, GSM has
become the mobile
telephony standard
Wireless Long Distance (2)
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2G cellular
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Predominant today, uses digital technology, but
still circuit switched
2G can carry SMS service
It aims at digital telephony, but with certain ability
to carry data
2.5G (e.g. GPRS)---2.75G (e.g. CDMA)
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Adds data capacity to a 2G network
The problem with adoption has been pricing
Wireless Long Distance (3)
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3G
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Services include wide-area wireless voice telephony
and broadband wireless data, all in a mobile
environment.
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802.11 networks are short range
384k-2M
Costs to deploy not seen as tenable in many
circumstances
It faces the same pricing issues at 2.5G – perhaps
worse
Killer apps still not clear
Battery and input
Wireless Long Distance (4)
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4G
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A comprehensive IP solution where voice, data and
streamed multimedia can be given to users on an "Anytime,
Anywhere" basis
Features
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higher data rates than previous generations: 100M-1G (any two
points in the world)
premium quality and high security
Fully IP-based
Supporting a greater number of wireless devices that are directly
addressable and routable (IPv6)
Spectrally efficient and high network capacity
Pre-4G technologies
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WiMax, LTE, UMB...
Coming: An Internet of Things
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Wireless communications like promised by
4G will enable machine-to-machine Internet
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Sensor network
RFID tag
Devices are all connected to the Internet, with a
mix of wired and wireless technologies
A new business environment
The Role of the IS Department
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Three roles of IS department
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Create the telecom architecture
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Connectivity
Interoperability
Operate the network
Stay current with the technology
Conclusion
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The telecom world is complex, and getting more complex
every day
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The business world is becoming increasingly dependent on
telecom
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In the past, electronic data exchange
The Internet unleashed email
Web sites were then used to get noticed globally
Now it is used for transaction and business
The first generation of the Internet economy has been
wired.
The second is unwired