Date post: | 27-Dec-2015 |
Category: |
Documents |
Upload: | baldwin-carr |
View: | 217 times |
Download: | 3 times |
INTRODUCTION
T.Najah Al_Subaie
Kingdom of Saudi Arabia
Prince Norah bint Abdul Rahman University
College of Computer Since and Information System
NET331
NET331
Instructor: T.Najah AL-Subaie
Course URL: http://net331.wikispaces.com/
Text Book: • Behrouz A Frouzan ,”Data
Communications and Networking”, McGraw Hill, Fourth Edition.
• Tanebaum, ”Computer Networks “, Prentic-Hall
Course Objectives
Understanding the basics of computer Networks.
Understanding the types of network architectures
Understanding the principles of the layering concepts.
Understanding the importance of networks in different applications.
Grading
2 Quizzes: 10% Reading Summaries: 5% Mid term : 20% Home Works : 10% Presentation: 5% Final exam: 50%
DATA COMMUNICATIONS
Telecommunication Means communication at a distance.
Data Refers to information presented in whatever form is
agreed upon by the parties creating and using the data. Data communications
The exchange of data between two devices via some form of transmission medium such as a wire cable.
DATA COMMUNICATIONS
Data communication system has five components: Message Sender Receiver Transmission medium Protocol
Data Flow
Communication between two devices can be: Simplex
The communication is unidirectional; only one of the two devices can transmit.
Keyboard , monitor. Half Duplex
Each station can both transmit and receive , but not at the same time.
Walkie-talkies phones. Full Duplex
Both stations can transmit and receive simultaneously.
Network
A network is a set of devices (often referred to as nodes) connected by communication links. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network.
Network
Distributed Processing Task is divided among multiple computers.
Network Criteria Network must meet a number of criteria:
Performance Reliability Security
Network Criteria
Performance Can be measured in many ways:
Transmission time Response time.
Performance metrics: Throughput and delays. Throughput: network throughput is the average rate of
successful message delivery over a communication channel
Reliability Measured by frequency of failure, time required to recover
from a failure and other. Security
Includes protecting data from unauthorized access.
Physical Structures
Type of connection: Point to point.
Provides a dedicated link between two devices. Entire capacity of the link is reserved for
transmission between those two devices. Example: the connection between the remote
control and the television control system. Multipoint.
More than two specific devices share a single link.
Share the capacity of the channel
Physical Structures
Physical topology Refers to the way in which a network is laid
out physically. Four basic topologies:
Mesh Star Bus ring
Mesh
Every device has a dedicated point to point link to every other device.
For a network with n nodes. The number of physical links is n(n-1)/2
Pros Cons
Star Topology
Each device has a dedicated point to point link only to a central controller called a hub.
Number of links: Pros. Cons.
Ring Topology
Each device has a dedicated point to point connection with only the two devices on either side of it.
Pros. Cons.
Network Models
Network models are defined by a standards.
Standards are needed to allow heterogeneous devices to communicate with each other.
Two standards for network models: OSI (Open System Interconnection) Model. Internet Model.
Network Categories
Categories of the networks based on their sizes: Local Area Network
Privately owned and links the devices in a single office, building.
Size : few kilometers. Usually used to share resources between personal computers.
Wide Area Network Provides long distance transmission of information. (e.g.
country) Metropolitan Area Network
A network with a size between a LAN and WAN. (e.g. city) Internet
Two or more connected networks.
Protocols and Standards
Protocols: Set of rules that govern data communications.
Standards: Agreement upon rules.