Telecommunications&

The Internet

Basic Telecom Model

Computer Computer

Channelinterface

Channelinterface

Communication Channel

Typical Home Telecom Model

Computer Computer

Modem ModemAudio Phone Lines

Digitalsignals

Digitalsignals

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

Front EndProcessor

CPU

Controller

Computer

Channel

Multiplexer

PC PC PC

T

T

T

T

ConcentratorChannel

Network Topology

• Star Network

• Bus Network

• Ring Network

C

C CC

C C

C

C

C

C C

C

P

P

P

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

20Chapter 8

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

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 NetworksCompuServe

• 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 NetworksProdigy

• 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 NetworksAOL

• 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 Cable One

Consumer 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 BandwidthsOC-x mulitples of 51.85 Mbps

• OC-3 155 Mbps

• OC-12 622 Mbps

• OC-48 2,488 Mbps

• OC-96 4,977 Mbps

• OC-192 9,953 Mbps

• OC-768 39,812 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 Eastern ND• 134.234.xxx.xxx 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:// communication protocol• www.ndsu.nodak.edu web server hosting the page• /ndsu/latimer/ path to the page on the host server• index.html filename of the page• #events 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 .coke

– Generic domains e.g. .car .green

• http://mashable.com/2011/06/20/icann-top-level-domains/