Data Communications and Networking


Introduction



RS Maniaol

What hath God wrought?

- Samuel F.B. Morse

First telegraph message on 24 May, 1844 from Supreme Court chamber in Washington, D.C. to the B&O's Mount Claire Station in Baltimore, Maryland

Definition of Terms

Communication

Telecommunication

Data Communication

Communicating devices must be part of a data communicating system (DCS), a combination of hardware and software

Data

Components of a Data Communication System

Protocol

Sender

Receiver

Medium

Message

Effective DCS

  • Delivery
  • Accuracy
  • Timeliness
  • Jitter

Data Representation

  • Text
  • Numbers
  • Images
  • Audio
  • Video

Data Flow

Simplex

Half-duplex

Full-duplex/duplex

Direction of data at time 1

Direction of data at time 2

Network

set of devices (nodes) connected by communication links

uses distributed processing

Network Criteria

  • Performance
    • Transmit time
    • Response time
    • More throughput, less delay
  • Reliability
  • Security

Physical Structure: Type of Connection

Point to Point

Multipoint/Multidrop

Physical Structure: Topology

refers to the way in which a network is laid out physically

geometric representation of the relationship of all the links and nodes to one another

Mesh

Hub

Star

Bus

Tap

Drop line

Cable end

Cable end

Ring

Repeater

Hybrid

Daisy Chain

Tree Topology

Network Models

Allows heterogeneous networks created by different entities to communicate

OSI (Open Systems Interconnection) model defines a seven-layer network

Internet model defines a five-layer network

Categories of Network:

Local Area Network (LAN)

Categories of Network:

Wide Area Network (WAN)

Categories of Network:

Metropolitan Area Network (MAN)

Interconnection of Networks:

Internetwork

The Internet: History

internet

 

Internet

two or more networks that can communicate with each other

collaboration of more than thousands of interconnected networks

1967 - at an ACM meeting, Advanced Research Projects Agency presented ARPANET

small network of computers which used Interface Message Processors

UCLA, UCSB, SRI and UU connected in 1969 via software called Network Control Protocol

http://projet-arpanet.over-blog.com

The Internet: History

1972 - Vint Cerf and Bob Kahn worked on the Internetting Project

1973 - paper on Transmission Control Protocol (TCP)

protocols to achieve end-to end delivery, encapsulation, the datagram and functions of a gateway

split into TCP and IP

TCP responsible for higher-level functions such as segmentation, reassembly and error detection

IP handles datagram routing

The Internet: Today

Made up of many wide- and local-area networks joined by connecting devices and switching stations

Internet Service Providers provide Internet access to users

Peering vs Transit

Autonomous Systems  (AS)

collection of routers whose prefixes and routing policies are under common administrative control

Peering - two or more autonomous networks interconnect directly with each other to exchange traffic

Transit - one autonomous network agrees to carry the traffic that flows between another autonomous network and all other network

Peering vs Transit

A

B

Peering

Peering vs Transit

A

B

C

Transit

Transit

Peering vs Transit

A

B

C

Transit

Transit

D

Peering

Peering vs Transit

A

B

C

Transit

Transit

D

Transit

Internet Exchange Point

Submarine Cable Map

https://www.submarinecablemap.com/

Asia-Pacific Cable Network 2 (APCN-2)

https://www.submarinecablemap.com/

Southeast Asia Japan Cable (SJC)

https://www.submarinecablemap.com/

Protocols

Communication occurs between entities in different systems 

Entity - anything capable of sending or receiving information

Protocol - set of rules that govern data communications

Elements of a Protocol

Syntax - structure and format of data

Semantics - meaning of each section of bits

Timing - when data should be send and how fast they can be sent

Standards

creates and maintains an open and competitive market for manufacturers

guarantees national and international operability of data and telecommunications technology and processes

De facto ("by fact") - have not been approved by an organized body but have been adopted as standards through widespread use

De jure ("by law") - have been legislated by an officially recognized body

How are standards developed?

Standard creation committees

ISO, ITU-T, CCITT, ANSI, IEEE

Slow approval process

Forums

speeds up acceptance and use of technology

conclusions presented in standards bodies

Government Regulatory Agencies

FCC/NTC

To protect public interest

Standard Creation Committees

  • ISO - International Organization for Standardization
  • CCITT - Consultative Committee for International Telegraphy and Telephony
  • ITU-T - International Telecommunication Union - Telecommunication Standards Sector
  • ANSI - American National Standards Institute
  • IEEE - Institute of Electrical and Electronic Engineers
  • EIA - Electronic Industries Association

Internet Standards

A thoroughly tested specification that is useful to and adhered to by those who work with the Internet

Specification begins as an Internet draft

work in progress, 6 month lifetime

Upon recommendation, may be published as Request for Comment

edited, assigned a number, made available to interested parties

Request for Comments

Invented by Steve Crocker to provide record of
Network Working Group's (NWG) design of the ARPANET

RFC 1 - “Host Software”

RFC 1000 - “Request for Comments Reference Guide”

RFC 1

References

  • Forouzan, B.A. 2007. Data Communications and Networking, 4th Ed.McGraw-Hill, New York
  • https://arstechnica.com/features/2008/09/peering-and-transit/
  • https://www.cs.rutgers.edu/~pxk/352/notes/autonomous_systems.html

DCN - Intro

By Rozano Maniaol

DCN - Intro

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