Telecommunications
&
The Internet
Basic Telecom Model
Computer
Computer
Channel
interface
Communication
Channel
Channel
interface
Typical Home Telecom Model
Computer
Digital
signals
Computer
Digital
signals
Modem
Modem
Audio Phone Lines
Analog signals
Channels
•
•
•
•
•
Twisted wire (twisted pair)
Coaxial Cable
Fiber Optics
Microwave
Newer Wireless
Twisted Pair
•
•
•
•
•
Low cost
easy to work with
installed infrastructure
crosstalk
300bps to 100Mbps
• “This modem is 56Kbps capable. However, current
regulations limit download speeds to 53Kbps,” the fine
print from a typical modem advertisement.
DSL
•
•
•
•
Uses existing twisted pair
256Kbps to 40Mbps
Loop length max about 18,000 ft.
More correctly ADSL (Asymmetric Digital
Subscriber Line) with download speeds
different from upload speeds.
Coaxial Cable
• More expensive
• harder to work with
• not as extensive an existing infrastructure
– cable TV companies are changing this
• 56Kbps to 550Mbps
Fiber Optics
•
•
•
•
Very expensive
difficult to work with
existing infrastructure limit to backbones
500Kbps to 30Gbps
Microwave
• Not as expensive as land lines
• Limited to line of site, (towers)
– reasonable infrastructure
• Satellite bounce, increases expense
– geo-synchronous (22,000 miles)
– low earth orbit (cheaper, lower power)
• 256Kbps to 100Mbps
Newer Wireless
– Cellular
– mobile data networks
– personal communications services (PCS)
– note: pagers & PDAs are not channels, they
would be nodes on one end of a channel
Transmission Speed
• BPS, bits-per-second, the amount of
information that can be transmitted through
a channel
• BAUD - a binary event, a signal change
from positive to negative or vice versa.
Speed II
• At higher speeds a single signal change can
transmit more than one bit at a time, so the
bit rate will generally be higher that the
baud rate.
• Transmission capacity is a function of the
frequency, higher frequency means higher
capacity
More Speed
• Bandwidth = range of frequencies that a
channel can support (difference between
highest and lowest frequency).
• Greater range means greater bandwidth.
• Greater bandwidth means greater
transmission capacity.
Faster Yet
• Bandwidth is like pipe diameter.
• Larger diameter pipes can transmit more
water in a given period of time.
• Personal Communication Services, PCSs,
have a greater bandwidth than fiber optics.
Communications Processors
Computer
Front End
Processor
Controller
Channel
T
Multiplexer
PC
PC
T
T
C
h
a
n
n
e
l
CPU
Concentrator
T
PC
Network Topology
• Star Network
C
C
C
P
C
• Bus Network
C
C
C
P
C
• Ring Network
P
C
C
C
C
Networks
• Local Area Network, LAN
• Wide Area Network, WAN
• Value Added Network, VAN
Network Terms
•
•
•
•
•
File server
Print server
Gateway - connects dissimilar networks
Bridge - connects similar networks
Routers - connects networks & directs traffic
• Similar networks = same network protocols
Transmission on LANs
• Token Ring
– can talk only when you have the token
– cost more than Ethernet
– better for high volume traffic
• Ethernet
– talk whenever you want
– send again if collision
– works best with low volume traffic
Chapter 8
20
Transmission on WANs & VANs
• Packet Switching
–
–
–
–
message broken into packets
packets may take various routes
message reassembled at destination
allows load balancing on channels
• Frame Relay
– like packet switching, no error correction
The Internet
• What is the Internet?
• Who owns the Internet?
• Why does the Internet exist?
Evolution of the Internet
• 1970 ARPANET - 15 nodes
• 1972 first email
• 1982 TCP/IP becomes internet standard
– Transmission Control Protocol/Internet Protocol
• 1984 ARPANET - 1,000 nodes
• 1986 NSF-Net backbone on ARPANET
• 1987 ARPANET - 10,000 nodes
Evolution of the Internet
• 1988 - businesses begin to connect to
system for research purposes
• 1989 ARPANET - 100,000 nodes
• 1989 link email between CompuServe and
ARPANET
• 1990 ARPANET becomes the Internet
Public Networks
CompuServe
• 1969 started in Cleveland with single
computer
• 1979 provided first email
• 1980 started national service
• Mid-1980s largest online service
• 1995 3 Million users
• 1997 purchased by AOL
Public Networks
Prodigy
• 1986 pilot in Atlanta, Hartford, San
Francisco
• 1988 national service launched
• 1994 1st to offer WWW access
• 1999 Prodigy Classic discontinued (209,000
members)
Public Networks
AOL
•
•
•
•
•
1991 AOL for DOS
1993 AOL for Windows
1997 bought CompuServe
1999 10 Million users
Estimated to have distributed over 1 Billion
discs of over 1,000 different disk/CD styles
Internet Statistics
• http://www.internetworldstats.com/stats.htm
– User Counts, updated daily
• http://whois.sc/internet-statistics/
– Domain Counts, updated daily
The Keys to Internet Growth
• 1991 WAIS and Gopher provide Internet
search and navigation
• 1992 WWW hyperlink software released
• 1992 NSF relaxes its restriction on
commercial Internet traffic
• 1992+ explosive growth in usage
Internet Capabilities
• Communications
–
–
–
–
E-mail
Usenet
Chatting
Telnet
• Information Retrieval
–
–
–
–
Gopher
Archie
WAIS
FTP
http://sunland.gsfc.nasa.gov/info/guide/Using_archie_Today.html
World Wide Web
• Set of standards for storing, retrieving,
formatting, and displaying information
using a client/server architecture
• Hypertext markup Language (HTML)
• browser
• search engines
Putting It All Together
AT&T
Level 3
Centurylink
I29
Consumer
Cable One
Consumer
Consumer
Some Upper Tier Providers
•
•
•
•
•
•
AT&T
Bell Atlantic
Bell South
Cable and Wireless
Cable One
GTE
•
•
•
•
•
•
IBM
MCI
Pacific Bell
QUEST
Sprint
US West
Tier 1 Networks
• The largest backbones on the Internet:
• Centurylink, Telecom Italia, Verizon, Sprint,
TeliaSonera International, NTT Communications,
Deutsche Telekom, Level 3, AT&T
• These top branded backbones only trade peering
traffic among themselves.
Common Bandwidths
•
•
•
•
•
•
•
56K modem
0.056 Mbps
ADSL
40 Mbps
Cable Modem
50 Mbps
T1
1.5 Mbps
Ethernet
10 to 1,000 Mbps
T3
44.7 Mbps
See http://bandwidthplace.com/
Upper Tier Bandwidths
OC-x mulitples of 51.85 Mbps
•
•
•
•
•
•
OC-3
OC-12
OC-48
OC-96
OC-192
OC-768
155
622
2,488
4,977
9,953
39,812
Mbps
Mbps
Mbps
Mbps
Mbps
Mbps
Organization Benefits of Internet
• Reducing Communication Costs
– virtual private net
• Enhancing Communication and Coordination
• Accelerating the Distribution of Knowledge
• Facilitating Electronic Commerce
Intranets
• An internal network based on World Wide
Web technology
• Firewall
– security software to prevent unauthorized
access to an intranet
• Firebreak
– a physical break between the Internet and
Intranet
Internet Challenges
• Security
• Technology Problems
–
–
–
–
incompatibility
limited bandwidth
telecommunications infrastructure
internet specialists
• Legal Issues
IP Addresses
• An identifier for a computer or device on a
TCP/IP network. Networks using the
TCP/IP protocol route messages based on
the IP address of the destination. The format
of an IP address is a 32-bit numeric address
written as four numbers separated by
periods. Each number can be zero to 255.
For example, 1.160.10.240 could be an IP
address.
IP Address Classes
•
•
•
•
Class A - 168.212.226.204
supports 16 million hosts on each of 127 networks
Class B - 168.212.226.204
supports 65,000 hosts on each of 16,000 networks
– NDUS has two Class B addresses
• 134.129.xxx.xxx
• 134.234.xxx.xxx
Eastern ND
Western ND
• Class C - 168.212.226.204
• supports 254 hosts on each of 2 million networks
IPv4 vs. IPv6
• IPv4
– 32 bits used for address
– 4,294,967,296
– Addresses not assigned by geographic region (see map)
• IPv6
– 128 bits used for address
– 340,282,366,920,938,463,374,607,431,768,211,456
– That about 3.7x10^21 addresses per square inch of the earth’s surface
– Addresses will be assigned by geographic region
IPv4 vs. IPv6
• IPv4 addresses written as four octets (8 bits)
separated by periods.
–
134.129.67.235
• IPv6 address written as eight 4-digit (16-bit)
hexadecimal numbers separated by colons.
–
1080:0:0:0:0:800:0:417A
Uniform Resource Locator
• http://www.ndsu.nodak.edu/ndsu/latimer/index.html#events
•
•
•
•
•
http://
www.ndsu.nodak.edu
/ndsu/latimer/
index.html
#events
communication protocol
web server hosting the page
path to the page on the host server
filename of the page
anchor in the page
IP & Domain Name Examples
• IP: 134.129.67.85
• URL: gdc.busad.ndsu.nodak.edu
• IP: 134.129.67.235
• URL: dyn235.minard-67.ndsu.nodak.edu
ICANN
• Internet Corporation for Assigned Names and Numbers
• a private sector, nonprofit organization
• responsibility for IP address space allocation, protocol
parameter assignment, domain name system management
and root server system management functions previously
performed under U.S. Government contract
• ICANN's diverse board consists of nineteen Directors, nine
At-Large Directors, who serve one-year terms and will be
succeeded by At-Large Directors elected by an at-large
membership organization. None of the present interim
directors may sit on the board once the permanent members
are selected.
IP Address Registries
• Regional Internet Registries:
• American Registry for Internet Numbers, ARIN
• Réseaux IP Européens Network Coordination
Centre, RIPE NCC
• Asia Pacific Network Information Centre, APNIC
• Latin American and Caribbean Internet Addresses
Registry, LACNIC
Internet Assigned Numbers
Authority
http://www.iana.org/
• Generic Top-Level Domains
– http://www.iana.org/gtld/gtld.htm
• ccTLD Database (country codes)
– http://www.iana.org/cctld/cctld-whois.htm
• IP Address Services
– http://www.iana.org/ipaddress/ip-addresses.htm
New Top-Level Domain Names
(TLDs)
• ICANN is accepting applications for new TLDs.
– Application window Jan. 12, 2012 to Apr. 12, 2012
– Application fee: $185,000
– Annual fee:
$25,000
• Intent is to move towards more descriptive names
• Companies (organizations) can create
– Brand domains e.g. .pepsi
– Generic domains e.g. .car
.coke
.green
• http://mashable.com/2011/06/20/icann-top-level-domains/
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