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

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

TelephoneNetwork ISPISPDSL

ModemDSLModem

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