1.3 Interpret Reference Model of OSI and TCP/IP
Communication Fundamentals
Message source
Signal-Transmitter
Transmission Medium
Receiver
Message Destination
Communication Fundamentals(Relationship between the five components)
1)Transmitter-Set of rules
2)Receiver-Set of Rules
3)Medium
4)Message
5)Protocol
Main elements of data communication systems
Message -It is the information to be communicated for example include text, pictures, audio, video and etc.
Sender-It is the device which sends the data message(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.
Rule Establishment
Protocols effective communication and include - An identified sender and receiver, Common language and grammar, speed and timing of delivery and comfirmation or acknowledgment requirements.
Protocols used in network communication also define -Message encoding, message delivery options, message formatting and encapsulation, message timing, message size.
Message encoding
Encoding between hosts must be in appropriate format for the medium.
Message Formatting and Encapsulation
There is an agreed format for letters and addressing letters which is required for proper delivery.
Message size
Long message 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.
Message Timing
Access method, Flow control, Response Timeout.
Message Delivery options
Unicast Message -One to one delivery.
Multicast Message- one to many delivery
Broadcast Message-One to all delivery
Communication methods
1)source(sender)- Message sources are people or electronic devices, that need to communicate a message to other individuals or devices
2)Destination (receiver)-The destination receives the message and interprets it.
3)Channel(Media)-message can travel from source to destination.
Among the protocols for successfull human communication are
identification of sender and receiver, agreed- upon medium or channel (face to face , telephone, letter, photograph), also common language.
Network protocols
How the message is formatted or structured
The process by which networking devices share information about pathways with other networks
Protocols interaction
HTTP, TCP, IP, ETHERNET
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Protocols suites and industry standards
May be specified by a standards organization or developed by a vendor
Development of TCP/IP
ARPANET was funded by the U.S. department of defense for use by universities and research laboratories.
TCP/IP Communication Process
The Ethernet information is then added creating the Ethernet Frame, or data link frame.
TCP/IP Communication Process (Cont)
First the ethernet header is removed
The Benefits of Using Layered Model
Assisting in protocol design since protocols at each layer have defined functions.
The OSI Reference Model
Presentation - provides for common representation of 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
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The TCP/IP Protocol model
Open standard, also called the TCP/IP model or the internet model.
OSI Model and TCP/IP Model comparison
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 the 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