1. MD703 Internet & Telecom Basics How the Net Works Key Technologies
IP Telephony
Solving the Last Mile Problem
Speed & Ubiquity Developments

2. 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
(electronic mail)
WWW (world wide web)
FTP (file transfer protocol)
UseNet newsgroups, PointCast, games, EDI, etc.

6. Transmission Speeds Bandwidth Bits & Bytes How do we measure speeds?
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

7. 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

8. Anatomy of a URL URL Uniform Resource Locator (web address)
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

9. The DNS & IP Addresses IP Address DNS - Domain Name Service
Unique number identifying Internet computers. Expressed as four numbers between 0 and 255.
ex: infoeagle.bc.edu = (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 (

10. 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 xxx.xxx domain)
Internet Leased Line through CW (4.5 Mbps, $8k/mo.)
The Internet
microsoft.com
local ISP
whitehouse.gov

11. TCP/IP TCP/IP - the Internet’s common language
TCP - Transmission Control Protocol. Breaks up transmissions ( 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.

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

13. A Packet Switched Network at Work
message:
Prof. Gallaugher,
I just wanted to let you know that I got a job based on the stuff I learned in your class...
message:
Prof. Gallaugher,
I just wanted to let you know ...
packet1
packet2
packet2 R R
packet1
packet3
packet3 R R
packet2
packet2
packet3
packet3 R
= router

14. US Internet Infrastructure
Watch Cable & Wireless’s backbone traffic at:
traffic.cwusa.com
Source:

15. TraceRoute from BC to Hawaii
1 cs7513-honolulu.aloha.net ( )
1.481 ms ms ms
( ) ms ms ms
3 sl-gw4-sea-5-0-T3.sprintlink.net ( ) ms ms ms
4 sl-bb1-sea-0-0.sprintlink.net ( ) ms ms ms
5 core2-hssi3-0.Seattle.mci.net ( ) ms ms ms
6 bordercore1.Boston.mci.net ( ) ms ms ms
7 boston-college.Boston.mci.net ( ) ms ms ms
8 Infoeagle.bc.edu ( ) ms ms ms

16. TraceRoute from BC to Albany, NY
1 be102 ( ) 2 ms 1 ms 1 ms
2 at-gw3-alb-1-0-T3.nysernet.net ( ) 2 ms 3 ms 2 ms
3 at-gw2-alb-0-0.nysernet.net ( ) 2 ms 3 ms 3 ms
4 at-gw1-syr-1-0-T3.nysernet.net ( ) 6 ms 4 ms 4 ms
5 at-gw1-ith-0-0-T3.nysernet.net ( ) 7 ms 7 ms 7 ms
6 at-gw2-ith-0-0.nysernet.net ( ) 7 ms 7 ms 7 ms
7 at-bb1-pen T3.nysernet.net ( ) 20 ms 20 ms 20 ms
8 sl-bb6-pen sprintlink.net ( ) 21 ms 23 ms 20 ms
9 core4-hssi5-0.WestOrange.mci.net ( ) 25 ms 26 ms 25 ms
10 bordercore1.Boston.mci.net ( ) 317 ms 54 ms 110 ms
11 boston-college.Boston.mci.net ( ) 36 ms 37 ms 36 ms
12 Infoeagle.bc.edu ( ) 36 ms 37 ms 36 ms

17. TCP will request packets that are lost or damaged
TCP vs. UDP
TCP - perfect transmission is critical (e.g. )
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

18. 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

20. Transmission Speeds The last mile problem The contenders
access to many consumers & businesses may be slow (e.g 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; Mbps download)

21. Bandwidth Bonanza (download speeds only)

22. Satellite Schemes GEO LEO Spaceway from Hughes (2003, 2-6 Mbps)
Teledesic (2004, 2 to 64 Mbps)
Graphic from Byte

23. 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