Chapter13Rev13 - Chapter 13 (Revision number 13) Evolution...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chapter 13 (Revision number 13) Evolution of networking and network protocols A computer box today does not provide the full functionality to a user without a connection to the Internet. While we take the Internet and network connectivity for granted, it is a revelation to review how we got to this point in the first place. This chapter starts with a journey through the evolution of networking from the early days of computing. We will then explore network protocols that allow computers to communicate with another. 13.1 Preliminaries As we mentioned in Chapter 10, peripheral devices interface with the rest of the computer system in one of two ways: programmed I/O ; or Direct Memory Access (DMA) . The former is appropriate for slow speed devices and the latter is appropriate for high- speed devices. The network, a high-speed device, uses DMA for interfacing with the system. 13.2 Telephony to Telecommunication Let us first review the evolution of telephony since computer networking owes a lot to the advances in telephony. Prior to 1960’s, the telephone infrastructure was entirely analog. That is, when you picked up a phone and called someone, the wires that connect the two devices carried actual voice signal. In principle, one could climb on a telephone pole and eavesdrop on private conversations, with a couple of electrical connections and a pair of headphones! In the 60’s, telephony switched from analog to digital. That is, the infrastructure converts the analog voice signal to digital, packetizes the ensuing bits, and sends the digital packets over the wire. At the receiving end, the infrastructure re- assembles the packets, converts them back to the original analog voice signal, and delivers them to the end user via the telephone (Figure 13.1).
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 A D 111100000010101010100100 Packetizing 11110000 00101010 10100100 111100000010101010100100 D A Reassembly Packets Telephone Infrastructure Figure 13.1 Infrastructure for Packet Switched Telephony 1960’s marked the era of mainframes in the computing evolution. These machines operated in a batch-oriented multiprogramming environment using punched cards as input/output medium. Cathode Ray Terminal (CRT) based display devices and keyboards made their way displacing punched cards as input/output medium for users to interact with the computer. This started the era of interactive computing and time-shared operating systems on the mainframes (Figure 13.2). Figure 13.2: Terminals connected to a Mainframe
Background image of page 2
3 With the parallel advances in telephony, the advent of CRTs opened up a new possibility. Can the terminals be remote? After all, the telephone infrastructure was carrying digital data. Therefore, the infrastructure does not really care if the bits on the wire represent voice or data! Unfortunately, the telephone infrastructure assumes that the input/output is analog (since it is meant for voice transmission) even though internally it is all digital!
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/25/2010 for the course CENG 100 taught by Professor Ceng during the Spring '10 term at Universidad Europea de Madrid.

Page1 / 52

Chapter13Rev13 - Chapter 13 (Revision number 13) Evolution...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online