• E-mail
• Desktop sharing
• E-commerce
Business
applicatictions
Home applications
• Twitter • Youtube • Facebook • Ubiquitous
computing
• Smart phone • GPS • M-commerce • Wearable computer
3 Network software
Layer
Protocol
service
Connect-oriented service
Connectless service
Network architecture
3.1 Network software-layer
layer
To reduce their design complexity, most networks are organized as a stack of layers or levels, each one built upon the one below it.
Mobile users
Social issues
• Sharing problems • Piracy • Privacy • Law problems
Uses of computer networks Network hardware Network software Reference models
The purpose of each layer is to offer certain services to the higher layers while shielding those layers from the details of how the offered services are actually implemented.
two layers, with the lower layer being the service provider and the upper layer being the service user.
Layers can offer two different types of service to the layers above them: connectionoriented and connectionless.
3.2 Network software-protocol
protocol
A protocol is an agreement between the communicating parties on how communication is to proceed.
As an analogy,when a woman is introduced to a man, she may choose to stick out her hand. He,in turn, may decide to either shake it or kiss it, depending, for example, on whethershe is an American lawyer at a business meeting or a European princess at a formal ball. Violating the protocol will make communication more difficult, if not completely impossible.
3.3 Network software-interface
interface
Interface is a connection point which exchange of information between the adjacent layers.
The interface defines which primitive operations and services the lower layer makes available to the upper one.
3.4 Network software-service
service A service is a set of operations that a layer
provides to the layer above it. A service relates to an interface between
2.1 Network hardware-transmission technology
Point-to- • Point-to-point links
point
connect individual pairs of machines
broadcast
• On a broadcast network,the communication channel is shared by all the machines on the network
2.2 Network hardware-scale
2.2.1 Network hardware-scale
Personal Area Networks
2.2.2 Network hardware-scale
Local Area Networks
2.2.3 Network hardware-scale
COMPUTER NETWORKS
TEACHER: HUAN
Uses of computer networks Network hardware Network software Reference models
1 Uses of computer networks
• Resource sharing(VPN)
Metropolitan Area Networks
2.2.4 Network hardware-scale
Wide Area Networห้องสมุดไป่ตู้s
Uses of computer networks Network hardware Network software Reference models