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