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 PointMAE – Metropolitan Area Exchange
The SONET
Hierarchy
Internet Backbone Circuit Capacity
See also the Mapnet project
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 CarrierSONET– Synchronous Optical Networking
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
(Computer A) TCP - Breaks message into data packetsIP - Adds address of destination Computer D
1 (Computer D) TCP - Checks for missing packets and reassembles message
3
(Router) Reads IP Address of packet, routes message to Network 2
2
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
TelephoneNetwork ISP
DSLModem
Copper Phone Line
Voice channelUpstream data channelDownstream 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 MbpsSource: Wikipedia