MD253 / MK253Electronic Commerce

April 19, 2006 Telecom

How the Internet WorksTelecommunication Markets

Issues Covered

• How the Internet Works– IP addresses, TCP/IP, packet switching, and why

you should care

• Telecom markets– RBOCs, Cable, CLECs, VoIP, and more– Crushing monopolies, shifting billions in wealth

The Transmission Speed Crib Sheet

• Bandwidth– measure of transmission speed / capacity

• Bits & Bytes– bit - smallest form of computer memory - 1 or 0– byte - 8 bits, roughly 1 character (Latin alphabet)

• How do we measure speeds?– bps - bits per second– Kbps - kilobit, thousands of bits per second– Mbps - megabit, millions of bits per second– Gbps - gigabit, billions of bits per second– Tbps – terabit, trillions of bits per second (a.k.a wicked fast)

Anatomy of a URL

• URL– Uniform Resource Locator (web address)

http://www2.bc.edu/~gallaugh/directory/file.html

application protocol(http is assumed by current browsers).Others: FTP, NNTP

host(others@ BC:agora,www)

domain name,top level domain

user ID

directory file

case sensitive

The DNS & IP Addresses• IP Address

– Unique number identifying Internet computers. Expressed as four numbers between 0 and 255.

– ex: www.bc.edu = 136.167.2.96 (32 bit address)– IPv6: 128 bit addressing, more efficient/faster, secure

• DNS - Domain Name Service– A distributed database used to translate host/domain names, into Internet

Protocol (IP) Addresses.

• Registry of an Internet domain name:– for com, net, org, over 60 firms (see icann.org for list)– for country-specific domains (.jp,.uk, .tv) fees vary widely (see icann.org for

list)

Network Interconnectionsdial-in

users (56.6 Kbps)dormusers

class/officeusers

dorm LAN office LANmodem pool

web serverwww2.bc.edu

BC Campus Network Backbone (1 Gbps)(IP #s 136.167.xxx.xxx domain)

Internet Leased Line through our ISPs (100 Mbps)

The Internet

local ISPgoogle.com whitehouse.gov

wireless

RR

stanford.edu

TCP/IP

• TCP/IP - the Internet’s common language

• TCP - Transmission Control Protocol. Breaks up transmissions (e-mail messages, web pages, etc.) into packets of no more than about 1500 characters each, checks the integrity of incoming packets, and reassembles packets on the other end

• IP - Internet Protocol. Routes packets.

Packet Traffic

• What’s in a packet?– source address– destination address– error checking (checksum)– time to live– options (timestamp, record route, etc.)– your data!

A Packet Switched Network at Work

E-mail message:

Prof. Gallaugher,I just wanted to let you know that I got a job based on the stuff I learned in your class...

packet1

packet2

packet3

E-mail message:

Prof. Gallaugher,I just wanted to let you know ...

packet2

packet1

packet3

packet1

packet2

packet3

packet2

packet3

R

R

R R

R

R = router

US Internet Infrastructure

Portions of the Abilene Intenet2 Backbone

Circuit vs. IP TelephonyCircuit Switching

Internet VoIP (e.g. Vonage, AT&T CallVantage, Skype)

Private Network VoIP (e.g. corporate VoIP)

Guaranteed QoS (quality of service)

packets over the Internet, variable QoS

packets over private network, improved QoS

The Internet

Private IP Network

Words from the PowerfulVoIP is the most significant paradigm shift in the entire history of modern communications since the invention of the telephone.

Employees ask me what I’m most excited about and I tell them Voice over the Internet. It is going to be a really big deal for us.

Former FCC Chair Michael Powell Time Warner CEO Richard Parsons