02-08-2013, 12:30 PM
COMPUTER NETWORKS
COMPUTER NETWORKS.ppt (Size: 1.83 MB / Downloads: 150)
INTRODUCTION:
A computer network is a group of interconnected computers
A collection of computers and devices connected to each other.
Allows computers to communicate with each other and share resources and information.
Building a Network
To build a network
Identify the set of constraints and requirements based on
Application programmer
Network designer
Network provider
Network Architecture
Provides a general, effective, fair, and robust connectivity of computers
Provides a blueprint
Types
OSI Architecture
Internet Architecture
OSI ARCHITECTURE
Open Systems Interconnection (OSI) model is a reference model developed by ISO (International Organization for Standardization) in 1984
OSI model defines the communications process into Layers
Provides a standards for communication in the
network
Primary architectural model for inter-computing and Inter networking communications.
network communication protocols have a structure based on OSI Model
Direct Links: Outline
Physical Layer
Link technologies
Encoding
Link Layer
Framing
Error Detection
Reliable Transmission (ARQ protocols)
Medium Access Control:
Existing protocols: Ethernet, Token Rings, Wireless
Stop And Wait ARQ
The source station transmits a single frame and then waits for an acknowledgement (ACK).
Data frames cannot be sent until the destination station’s reply arrives at the source station.
It discards the frame and sends a negative acknowledgement (NAK) back to the sender
causes the source to retransmit the damaged frame in case of error
Tree
Is a logical extension of the bus topology.
The transmission medium is a branching cable
no closed loops.
The tree layout begins at a point called the head-end
one or more cables start, and each of these may have branches.
The branches in turn may have additional branches to allow quite complex layouts.