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Chapter 1.3 Interpret Reference model of OSI and TCP/IP. - Coggle Diagram
Chapter 1.3
Interpret Reference model of OSI and TCP/IP.
topic 1.3.1:
Types of rules that are necessary to successfully communicate
Communication Fundamentals
computer communication
message
message source
signal
transmitter
transmission medium
signal
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relationship between the five components
1) transmitter
3) medium
2) receiver
set of rules
4) message
set of rules
agreement between the communicating devices
5) protocol
main elements of data communication system
message - it is the information to be communicated. popular forms of information include text,pictures,audio,video and etc
sender - it is the device which send the data messages. it can be a computer,workstation,telephone handset 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
protocol - it is 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
protocol are necessary of 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 encoding
message delivery options
message formating and encapsulation
message timing
message size
the rules
MESSAGE ENCODING:
encoding between hosts must be in appropriate format for the medium
messages are first converted into bits by the sending hosts.
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 interpret the message
MESSAGE FORMATING 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 SIZE:
Humans break long messages into smaller parts or sentences.
Long messages must also be broken into smaller pieces to travel across a network.
each piece is sent 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 begins 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.
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.
1.3.2 why protocols are necessary in network
rules that Govern Communications
protocol suites are implemented by hosts and networking devices in software,hardware or both.
the protocols are viewed in terms of layers,with each higher level service depending on the functionality defined by the protocols shown in the lower levels.
among the protocols for successful human communication are:
identification of sender and receiver
agreed-upon medium or channel (face-to-face,telephone,letter,photograph)
appropriate communication mode (spoken,written,illustrated,interactive or one-way).
common language
5.grammar and sentence structure
speed and timing of delivery.
imagine what would happen if no protocols or rules existed to govern how people communicate with each other.
would you be able to understand them?
are you able to read the paragraph that does not follow commonly accepted protocols?
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), internet protocol (IP)
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.
protocol interaction
communication between a web server and web client is an example of an interaction between several protocols:
HTTP - an application protocol that governsthe way a web server and a web client interact.
TCP - transpot 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 and industry standards.
a protocol suite is a set of protocols that work together to providecomprehensive network communication services.
may be specified by
a standards organization or developed by a vendor.
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.
development of TCP/IP
advanced research projects agency network (ARPANET) was the predecessor to todays internet.
ARPANET was funded by the U.S Department of Defense for use by universities and research laboratories.
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 trnasport 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.
this frame is delivered to the nearest router along the path towards the web client.each router adds new data link infotmation before fowarding the packet.
TCP/IP communication Process (Cont.)
when receiving the data link frames from 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.
1.3.3 how the TCP/IP model and the OSI model are used to facilitate standardization in the communication process
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 the one layer from affecting other layers.
providing a common language to describe networking functions and capabilities.
the OSI reference model.
application- contains protocols used to 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 7 layers of OSI
7 LAYERS
application
presentation
session
transport
network
data link
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PDU
message
message
message
segment
packet
frame
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PURPOSE
interface with application
data translation & prep for network
estab.&maintain comm link
breaks down mssg to send
adds logical address info
adds physical addressing
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PROTOCOLS
SMTP,DNS,HTTP,FTP,T ELNET,RIP,ECT
MP3,JPG,(compression),encryption,ect
NTFS,SQL,RPC,NETBOIS,UDP,NCP,ADSO, ECT.
TCP,UDP,NWLink,SPX,NBP,ATP,SPP,ect.
IPX,RIP,DDP,RTMP,IP,ARP,RARP,ICMP,OSPF,etc.
802.3 enthernet,802.5 token ring,802.11 wireless,FIDDI X.25,STP,etc.
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OSI model and TCP/IP model comparison
in the OSI model,the network access layer and the application layer of the TCP/IP model are further divided to describe discrete functions that must occur at these layers.
SIMILARITIES
share similar architecture
share a common application layer
both models have comparable transport and network layers.
knowledge of both models is required by networking professionals.
differences
protocol standard
combines he presentation and session layer issues into its application layer
combines the OSI data link and physical layers into the network access layer
a simpler model