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TECHNOLOGY GUIDE 5
Basics of the Internet and the World
Wide Web
The Internet
 Began as a government-
sponsored network for
research and education
 Became commercialized in 1993 with the World Wide
Web innovation
 Based on two protocols (TCP/IP)


Transmission Control Protocol (TCP)
Internet Protocol (IP)
 Most users connect to it through an Internet Service
Provider (ISP)
Architecture of the Internet
NAP – Network Access Point
MAE – Metropolitan Area Exchange
Internet Backbone Circuit Capacity
Type of Circuit
Data Rate
T1
1.544 Mbps
T3
44.74 Mbps
OC-1
51.84 Mbps
OC-3
155.52 Mbps
OC-12
622.08 Mbps
OC-24
1.244 Gbps
OC-48
2.488 Gbps
OC-192
9.95 Gbps
OC-768
39.81 Gbps
OC – Optical Carrier
SONET– Synchronous Optical Networking
The
SONET
Hierarchy
See also the Mapnet project
Identifying Computers on the Internet
(Addressing)
 Domain name (symbolic address)
 e.g., www.csun.edu, www.yahoo.com
 IP Address (numeric address)
 e.g., 130.166.1.254, 130.166.105.77
 URLs (Uniform Resource Locators) – identify
paths to a Web page or document

e.g., http://www.csun.edu/webmail
How the Internet Works – Packet
Switching
Packet Switching
• Allows millions of users to send large and small chunks of data
across the Internet concurrently
• Based on the concept of turn taking, packets from each user are
alternated in the shared network
Another Look at Packet Switching
How TCP/IP Work to Deliver
Messages
Example: Delivering a message from Computer A to Computer D
2
(Router)
Reads IP Address of
packet, routes message
to Network 2
1
(Computer A)
TCP - Breaks message
into data packets
IP - Adds address of
destination Computer D
3
(Computer D)
TCP - Checks
for missing packets and
reassembles message
Accessing the Internet (the Last Mile)
 Amdahl’s Law: A network connection can be no
faster than its slowest link
 Speed of the Internet often limited by the local
access technology (the last mile)
 Broadband Internet Access (FCC): 768 kbps
minimum

For HD streaming video, need at least 5 Mbps
 How fast is your Internet access?
Digital Subscriber Line (DSL)
 Combine voice and high-speed data on a single
phone line



Users do not share access lines
1.5 – 9 Mbps downstream, 16 – 640 Kbps upstream
Distance-sensitive
DSL
Modem
Telephone
Network
ISP
Copper Phone Line
Voice channel
Upstream data channel
Downstream data channel
Cable Modem
 Allocates a small portion of a cable TV system’s
high bandwidth media for data transmission

1.5 – 30 Mbps downstream, 384Kbps – 1.5 Mbps upstream
Fixed or Mobile Wireless Access
 Cellular network
 Internet-enabled cellular phones
 User can move within cellular coverage area
 Wi-Fi (WLAN)
 User can move within range of a Hot Spot
 Fixed wireless (WiMax) with ranges up to 50 km
Fiber to the X Service
 Fiber to the Node
 Fiber to the Curb
 Fiber to the Building
 Fiber to the Home
 Sweden leads the
world in FTTH

Average download speed is
86 Mbps
Source: Wikipedia