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