expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Overview of Overview of Data Communications Data Communications
and and NetworkingNetworking
PART IPART I
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Chapters
Chapter 1 Introduction
Chapter 2 Network Models
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
1.1 Data Communication
•Data communication is the transfer of data from one device to another via some form of transmission medium.
•A data communications system must transmit data to the correct destination in an accurate and timely manner.
•Components
•Data Representation
•Direction of Data Flow
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.1 Five components of data communication
are the message, sender, receiver, medium, and protocol.
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Data Representation text, numbers, images, audio, and video are different forms of information.
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.2 Simplexe.g. the keyboard and the monitor
Direction of Data Flow
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.3 Half-duplexe.g. Walkie-talkies, CB radios
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.4 Full-duplex
e.g. 2 people are communicating by a tel. line
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
A network is a set of communication devices connected by media links.
1.2 Networks
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
1.2 Networks
1.Distributed Processing• Task is divided
2.Network Criteria• Important: performance,
reliability, security
3.Physical Structures
4.Categories of Networks
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.5 Point-to-point connection
Physical Structures
3. Physical Structures
In a point-to-point connection, two and only two devices are connected by a dedicated link.
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.6 Multipoint connection (timeshare connection – capacity)
In a multipoint connection, three or more devices share a link.
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
1.2 NETWORKS How do we categorize?
Topology, geography Technology
Geographic Wide area networks Metropolitan networks Local area networks Personal networks
Technologies Circuit switched Packet switched
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.7 Categories of topology (a network is layout physically)
A topology is the geometric representation of the relationship of all the links and linking devices
4. Categories of Networks
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.8 Fully connected mesh topology (for five devices)
Every device has a dedicated point to point link to every other device
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.9 Star topology
Each device has a dedicated point to point link only to a central controller, called a hub
If one device wants to send data to another. •It sends the data to the controller, which then relays the data to the other connected device.
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.10 Bus topology is multipoint, previous all were point to point
connector
connection
One long cable acts as a backbone
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.11 Ring topology
Each device has a dedicated point to point link only with 2 devices on either side of it.
When a device receives a signal intended for another device, its repeater regenerates the bits and passes them along.
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.12 Categories of networks
A network falls is determined by criteria:1. Its size2. Its ownership3. The distance
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.13 LAN - Local Area Network
•Designed for a single office, campus, building or between nearby buildings. •LANs allow resources to be shared
•Hardware•Software•Data
between PCs or workstations.•License restriction
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.13 LAN (Continued)
A given LAN use only one type of transmission medium.
Speed : 4-16 MbpsToday: 100 Mbps
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.14 MAN Metropolitan Area Network (e.g. cable TV)
Designed to extend over an entire city, connects LANs
LANs can be shared
- offices can be connected via a city
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.15 WAN - Wide Area Network
Provides all transmission (data, video, image etc.) over large areas e.g. states, countries, a continent , or the whole world.
In contrast to LANs may utilize public, leased, or private communication equipment.
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
EO - End OfficePSTN – Public Switching Telephony NetworkPBX – Private Exchange Switch
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
1.3 The Internet1.3 The Internet
•A Brief History•The Internet Today
•When 2 or more networks are connected, they become an internetwork, or internet.
•An internet is a network of networks.
•The Internet (upper case) is a collaboration of more than 100s thousands interconnected networks.
•The Internet is a structured, organized collection of many separate networks.
•TCP/IP is the protocol suite for the Internet.
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.16 Internet today
NAP = Network Access Point is the complex switching stations.Speed: up to 600 Mbps
•End users to be connected use the services of Internet Service Provider (ISP)
There are local, regional, national, and international Internet service providers (ISPs).
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Figure 1.16 Internet today
NAP = Network Access PointUp to 600 Mbps
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
1.4 Protocols and Standards1.4 Protocols and Standards
•Protocols •Set of rules that governs data communication•Key elements:
•Syntax•Structure or format – order in which they are presented
•Semantics•Meaning of each section of bits
•Timing•What data and how fast they can be sent
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
A standard provides a model for development that enables a product to work regardless of the individual manufacturer
Standards are essential in: i. Creating competitive markets for
equipment manufacturers ii. Guaranteeing national and
international interoperability and compatibility
1.4 Standards1.4 Standards
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
De Facto (by fact) standards Proprietary Nonproprietary
De Jure (by law) standards
1.4 Standards Categories1.4 Standards Categories
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Standards Organizations The ISO, ITU-T (previously CCITT), ANSI, IEEE, and EIA
are some of the organizations involved in standards creation.
1.4 Protocols and Standards1.4 Protocols and Standards
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Forum Consist of representatives from
interested corporations Present their conclusions to the standards
bodies Facilitate standardization process
Frame Relay Forum ATM Forum and Consortium Internet Society (ISOC) and Internet Engineering Task Force (IETF)
1.4 Protocols and Standards1.4 Protocols and Standards
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Forum are special-interest groups (work
with universities and users), that evaluate and standardize new technologies.
Internet Standards A Request for Comment (RFC) is an
idea or concept that is a precursor to an Internet standard.
1.4 Protocols and Standards1.4 Protocols and Standards
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
ISO (International Standards Organization) 1946 – vast number of subjects
89 countries 13000 standards ISO is a member of ITU-T Documents are:
Draft Draft International International Standard
ANSI (American National Standards Institute) Private, nongovernmental, nonprofit organization
NIST (National Institute of Standards and Technology) – a part of the US Dept of Commerce
IEEE (Institute of Electrical and Electronics Engineering)
Largest professional organization in the world ITU-T International Telecommunications Union -
Telecommunications Standardization Sector (former CCITT) – 3000 recommendations
1.4 Protocols and Standards1.4 Protocols and Standards
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
ISO ISO 8877—Interface in Integrated
Services Digital Network (ISDN) ISO 3309—HDLC frame structure ISO 8028—X.25 packet level protocol
1.4 Protocols and Standards1.4 Protocols and Standards
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
ITU-T V.32: Defines data transmission over
phone lines X.25: Defines transmission over public
digital networks I.430: Define physical layer
specifications for an interface
1.4 Protocols and Standards1.4 Protocols and Standards
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
ANSI X3. 23-1985 Programming language
COBOL SONET Synchronous Optical Network ISDN Integrated Services Digital
Network
1.4 Protocols and Standards1.4 Protocols and Standards
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
IEEE IEEE 802.3: CSMA/CD LAN IEEE 802.4: Token Bus LAN IEEE 802.5: Token Ring LAN
1.4 Protocols and Standards1.4 Protocols and Standards
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
EIA EIA-232: A 25-pin interface standard EIA-449: Specifies a 37-pin connector
and a 9-pin connector EIA-530: Defines a 25-pin connector
1.4 Protocols and Standards1.4 Protocols and Standards
expanded by Jozef GoetzMcGraw-Hill ©The McGraw-Hill Companies, Inc., 2004
Federal Communication Commission (FCC)
Authority for interstate and international traffic Reviews communication services and prices Reviews technical specs of communication
hardware Assigns carrier frequencies for radio and
television
Public Utility Commission Authority for intrastate traffic
1.4 Regulatory Agencies1.4 Regulatory Agencies