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MD703. Internet & Telecom Basics How the Net Works Key Technologies IP Telephony Solving the Last Mile Problem Speed & Ubiquity Developments. What is the Internet?. A Network of Networks TCP/IP - standard protocol for routing & transport A medium of exchanging all form of digital data

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Md703

MD703

Internet & Telecom Basics

How the Net Works

Key Technologies

IP Telephony

Solving the Last Mile Problem

Speed & Ubiquity Developments


What is the internet

What is the Internet?

  • A Network of Networks

    • TCP/IP - standard protocol for routing & transport

  • A medium of exchanging all form of digital data

    • text, graphics, audio, video, programs, faxes

  • An infrastructure for various services

    • e-mail (electronic mail)

    • WWW (world wide web)

    • FTP (file transfer protocol)

    • UseNet newsgroups, PointCast, games, EDI, etc.


Transmission speeds

Transmission Speeds

  • 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


How many people use the net

How Many People Use the Net?

  • We don’t know

  • Nua’s best guess - about 201 million at 9/99

  • Breakdown:

Source: nua.ie, Sept. 99


Anatomy of a url

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 computer

(others

@ BC:

agora,

www)

domain name,

top level domain

user ID

directory

file

case sensitive


The dns ip addresses

The DNS & IP Addresses

  • IP Address

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

    • ex: infoeagle.bc.edu = 136.167.2.241 (32 bit address)

    • IPv6: 128 bit addressing, more efficient/faster, secure

  • DNS - Domain Name Service

    • A distributed database used to translate domain names, into Internet Protocol (IP) Addresses.

  • Registry of an Internet domain name:

    • currently in the US for $70 for two years (www.internic.net)


Network interconnections

Network Interconnections

dial-in

users (56.6 Kbps)

dorm

users

office

users

web server

www2.bc.edu

modem pool

dorm LAN

office LAN

BC Campus Network Backbone (10 Mbps)

(IP #s 136.167.xxx.xxx domain)

Internet Leased Line through CW (4.5 Mbps, $8k/mo.)

The Internet

microsoft.com

local ISP

whitehouse.gov


Tcp ip

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

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

R

R

R

R

R

R

A Packet Switched Network at Work

packet1

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...

E-mail message:

Prof. Gallaugher,

I just wanted to let you know ...

packet1

packet2

packet2

packet1

packet3

packet3

packet2

packet2

packet3

packet3

= router


Us internet infrastructure

US Internet Infrastructure

Watch Cable & Wireless’s backbone traffic at:

traffic.cwusa.com

Source: [email protected]


Traceroute from bc to hawaii

TraceRoute from BC to Hawaii

1 cs7513-honolulu.aloha.net (204.94.112.38)

1.481 ms 1.084 ms 0.942 ms

2 207.170.197.201 (207.170.197.201) 72.109 ms 71.315 ms 73.781 ms

3 sl-gw4-sea-5-0-T3.sprintlink.net (144.228.96.9) 75.242 ms 79.062 ms 77.557 ms

4 sl-bb1-sea-0-0.sprintlink.net (144.228.90.1) 79.245 ms 74.64 ms 75.174 ms

5 core2-hssi3-0.Seattle.mci.net (206.157.77.153) 76.262 ms 75.853 ms 77.16 ms

6 bordercore1.Boston.mci.net (166.48.60.1) 145.921 ms 142.257 ms 142.892 ms

7 boston-college.Boston.mci.net (166.48.62.14) 154.438 ms 148.711 ms 151.135 ms

8 Infoeagle.bc.edu (136.167.2.146) 150.337 ms 149.579 ms 154.07 ms


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TraceRoute from BC to Albany, NY

1 be102 (169.226.4.1) 2 ms 1 ms 1 ms

2 at-gw3-alb-1-0-T3.nysernet.net (169.130.23.5) 2 ms 3 ms 2 ms

3 at-gw2-alb-0-0.nysernet.net (169.130.20.2) 2 ms 3 ms 3 ms

4 at-gw1-syr-1-0-T3.nysernet.net (169.130.1.22) 6 ms 4 ms 4 ms

5 at-gw1-ith-0-0-T3.nysernet.net (169.130.1.42) 7 ms 7 ms 7 ms

6 at-gw2-ith-0-0.nysernet.net (169.130.60.2) 7 ms 7 ms 7 ms

7 at-bb1-pen-5-0-0-T3.nysernet.net (169.130.1.121) 20 ms 20 ms 20 ms

8 sl-bb6-pen-6-0-0.sprintlink.net (144.228.60.21) 21 ms 23 ms 20 ms

9 core4-hssi5-0.WestOrange.mci.net (206.157.77.105) 25 ms 26 ms 25 ms

10 bordercore1.Boston.mci.net (166.48.60.1) 317 ms 54 ms 110 ms

11 boston-college.Boston.mci.net (166.48.62.14) 36 ms 37 ms 36 ms

12 Infoeagle.bc.edu (136.167.2.146) 36 ms 37 ms 36 ms


Tcp vs udp

TCP vs. UDP

TCP - perfect transmission is critical (e.g. e-mail)

TCP will request packets that are lost or damaged

The Internet

UDP = User Datagram Protocol

UDP - low latency is critical (e.g. RealAudio, Video, packet streaming)

Latency matters - UDP will ignore packets that don’t arrive on time or in good shape

The Internet


Circuit vs ip telephony

Circuit vs. IP Telephony

Circuit Switching

64 Kbps circuit, guaranteed QoS (quality of service)

Internet Telephony (e.g. Net2Phone)

packets over the Internet, variable QoS

The Internet

IP Telephony over Private Networks (e.g. Qwest)

packets over private network, improved QoS

Private IP Network


Transmission speeds1

Transmission Speeds

  • The last mile problem

    • access to many consumers & businesses may be slow (e.g. 28.8 Kbps modem speeds)

  • The contenders

    • faster modems - (at ISP and user end; 56 Kbps)

    • ISDN - (e.g. BellAtlantic; up to 128 Kbps)

    • GEO Satellite (e.g. DirectDuo; 400 Kbps download)

    • LMDS (e.g. CellularVision; 500 Kbps download)

    • Cable Modems (e.g. MediaOne; 1.5 Mbps download)

    • ADSL (e.g. AmeriTech; 1.5 - 7 Mbps download)


Bandwidth bonanza download speeds only

Bandwidth Bonanza(download speeds only)


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Satellite Schemes

  • GEO

    • Spaceway from Hughes (2003, 2-6 Mbps)

  • LEO

    • Teledesic (2004, 2 to 64 Mbps)

Graphic from Byte


Fostering speed ubiquity

Fostering Speed & Ubiquity

  • Caching servers

    • get content closer to customers

    • e.g. Akamai, Inktomi, Digital Island

  • Dense Wave Division Multiplexing

    • prisms split fiber optic signal

  • Wireless Access

    • WAP, i-mode, emerging 3G standards

  • Integration of Wireless Devices

    • Bluetooth


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