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INTRODUCTION TO NETWORK CHAPTER 1.3 - Coggle Diagram
INTRODUCTION TO NETWORK
CHAPTER 1.3
Communication Fundamentals
Main elements of data communication systems
Message - It is the information to be communicated. Popular forms of
information include text, pictures, audio, video and etc.
Receiver - It is the device which receives the data messages. It can be a
computer, workstation, telephone handset etc.
Transmission Medium - It is the physical path by which a message travels from
sender to receiver. Some examples include twisted-pair wire, coaxial cable,
radio waves and etc.
Sender - It is the device which sends the data messages. It can be a computer,
workstation, telephone handset and etc.
Protocol - It is a set of rules that governs the data communications.It
represents an agreement between the communicating devices.Without a
protocol, two devices may be connected but not communicating.
Rule
Establishment
Protocols are necessary for effective communication and include
An identified sender and receiver
Common language and grammar
Speed and timing of delivery
Confirmation or acknowledgment requirements
Protocols used in network communications also define:
Message Size
Long messages must also be broken into smaller pieces to travel across a network:
Each piece is sent in a separate frame
Each frame has its own addressing information
A receiving host will reconstruct multiple frames into the original message.
Message Timing
Access Method
Hosts on a network need to know when to begin sending messages and how to respond when collisions occur
Flow Control
Source and destination hosts use flow control to negotiate correct timing to avoid overwhelming the destination and ensure information is received
Response Timeout
Hosts on the network have rules that specify how long to wait for responses and what action to take if a response timeout occurs
Message Formatting and Encapsulation
There is an agreed format for letters and addressing letters which is required for proper delivery. Putting the letter into the addressed envelope is called encapsulation. Each computer message is encapsulated in a specific format, called a frame, before it is sent over the network. A frame acts like an envelope providing destination address and source address.
Message Delivery Options
Unicast Message
Multicast Message
Broadcast Message
Message Encoding
Encoding between hosts must be in appropriate format for the medium. Messages are first converted into bits by the sending host. Each bit is encoded into a pattern of sounds, light waves, or electrical impulses depending on the network media. The destination host receives and decodes the signals in order to interpret the message.
Communication methods
All communication methods have three elements in common
Source (Sender) - Message sources are people, or electronic devices, that need to communicate a message to other individuals or devices
Destination (Receiver) - The destination receives the message and interprets it
Channel (Media) - Provides the pathway over which the message can travel from source to destination.
**Network Protocols
Networking protocols define a common format and set of rules for exchanging messages between devices
Some common networking protocols are Hypertext Transfer Protocol (HTTP), Transmission Control Protocol (TCP), and Internet Protocol (IP).
Protocol Interaction
(Communication between a web server and web client)
HTTP - an application protocol that governs the way a web server and a web client interact
TCP - transport protocol that manages the individual conversations
IP – encapsulates the TCP segments into packets, assigns addresses, and delivers to the destination host
Ethernet - allows communication over a data link and the physical transmission of data on the network media.
Protocol Suites
A protocol suite is a set of protocols that work together to provide comprehensive network communication services.
Development of TCP/IP
The TCP/IP protocol suite is an open standard, the protocols are freely available, and any vendor is able to implement these protocols on their hardware or in their software
:
TCP/IP Communication Process
When sending data from a web server to a client the encapsulation procedure would be as follows:
The webserver prepares the Hypertext Markup Language (HTML) page The HTTP application layer protocol sends the data to the transport layer
The transport layer breaks the data into segments and identifies each
Next the IP source and destination addresses are added, creating an IP Packet
The Ethernet information is then added creating the Ethernet Frame, or data link frame.
When receiving the data link frames from the web server, the client processes and removes each protocol header in the opposite order it was added:
First the Ethernet header is removed
Then the IP header
Then the Transport layer header
Finally the HTTP information is processed and sent to the client’s web browser
The role of protocols
How the message is formatted or structured
The process by which networking devices share information about pathways with other networks
How and when error and system messages are passed between devices
The setup and termination of data transfer sessions
The benefits of using a layered model include :
Assisting in protocol design since protocols at each layer have defined functions
Fostering competition because products from different vendors can work together
Preventing technology changes in one layer from affecting other layers
Providing a common language to describe networking functions and capabilities.
OSI MODEL
Application - contains protocols used for process-to process communications
Presentation - provides for common representation of the data
Session - provides services to the presentation layer to organize its dialogue and to manage data exchange
Transport - defines services to segment, transfer, and reassemble the data
Network - provides services to exchange the individual pieces of data over the network between identified end devices
Data Link - provides methods for exchanging data frames between devices over a common media
Physical - describes the mechanical, electrical, functional, and procedural means to transmit bits across physical connections
The TCP/IP Protocol Model
Different between OSI and TCP/IP
Different between OSI and TCP/IP
