OSI model
A device connected to another device share information and services is called network
there is two type reference model
• Open Systems Interconnection (OSI)
• The Department of Defense (DoD)
OSI Reference Model
The OSI (open system interconnection) model is conceptual or logical model. it was developed by
International Organization for Standardization(IOS)
OSI model consist of the seven layer.
The Session layer (Layer-5) is responsible for establishing, maintaining, and ultimately terminating sessions between devices. If a session is broken, this layer can attempt to recover the session.
The Transport layer (Layer-4) does not actually send data, despite its name. Instead, this layer is responsible for the reliable transfer of data, by ensuring that data arrives at its destination error-free and in order.
The Data-link layer packages the higher-layer data into frames, so that the data can be put onto the physical wire. This packaging process is referred to as framing or encapsulation.
The Physical layer (Layer-1) controls the signaling and transferring of raw bits onto the physical medium. The Physical layer is closely related to the Data-link layer, as many technologies (such as Ethernet) contain both datalink and physical functions.
The Physical layer provides specifications for a variety of hardware:
• Cabling
• Connectors and transceivers
• Network interface cards (NICs)
• Wireless radios
• Hubs
A device connected to another device share information and services is called network
there is two type reference model
• Open Systems Interconnection (OSI)
• The Department of Defense (DoD)
OSI Reference Model
The OSI (open system interconnection) model is conceptual or logical model. it was developed by
International Organization for Standardization(IOS)
OSI model consist of the seven layer.
Application
Presentation
Session
Transport
Network
Data-link
Physical
Application layer: provided a user interface eg. file print, message,
Presentation layer presents data, processing eg. Data encryption, compression decryption
Session layer : Data separate from different application
Transport layer : Provide reliable or unreliable delivery, perform error correction before transmit
Network layer : Provide logical address and router select path.
Data link layer: Provide access media using MAC, perform error detection and correct.
Physical layer: data fram into bits and moves, specific voltage and wire speed
Application layer: provided a user interface eg. file print, message,
Presentation layer presents data, processing eg. Data encryption, compression decryption
Session layer : Data separate from different application
Transport layer : Provide reliable or unreliable delivery, perform error correction before transmit
Network layer : Provide logical address and router select path.
Data link layer: Provide access media using MAC, perform error detection and correct.
Physical layer: data fram into bits and moves, specific voltage and wire speed
OSI Model - The Application Layer-7:
The Application layer (Layer-7) provides the interface between the user application and the network. A web browser and an email client are examples of user applications
The Application layer (Layer-7) provides the interface between the user application and the network. A web browser and an email client are examples of user applications
The user application itself does not reside at the Application layer - the
protocol does. The user interacts with the application, which in turn interacts
with the application protocol.
Example of application layer
• File transfer
• Email
•Client/ sever process
•Information location
OSI Model - The Presentation Layer
The Presentation layer (Layer-6) controls the formatting and syntax of user data for the application layer. This ensures that data from the sending application can be understood by the receiving application
Standards have been developed for the formatting of data types, such as text, images, audio, and video. Examples of Presentation layer formats include
If two devices do not support the same format or syntax, the Presentation layer can provide conversion or translation services to facilitate communication
The Presentation layer can perform encryption and compression of data,
OSI Model - The Session Layer
Example of application layer
• File transfer
•Client/ sever process
•Information location
OSI Model - The Presentation Layer
The Presentation layer (Layer-6) controls the formatting and syntax of user data for the application layer. This ensures that data from the sending application can be understood by the receiving application
Standards have been developed for the formatting of data types, such as text, images, audio, and video. Examples of Presentation layer formats include
If two devices do not support the same format or syntax, the Presentation layer can provide conversion or translation services to facilitate communication
The Presentation layer can perform encryption and compression of data,
OSI Model - The Session Layer
The Session layer (Layer-5) is responsible for establishing, maintaining, and ultimately terminating sessions between devices. If a session is broken, this layer can attempt to recover the session.
Dialog control between devices there is three way of communication
• Simplex : One way of communication
• Half-Duplex : Two way communication, at time person communicate
• Full-Duplex : simultaneous two way communication
• Simplex : One way of communication
• Half-Duplex : Two way communication, at time person communicate
• Full-Duplex : simultaneous two way communication
OSI Model - The Transport Layer
The Transport layer (Layer-4) does not actually send data, despite its name. Instead, this layer is responsible for the reliable transfer of data, by ensuring that data arrives at its destination error-free and in order.
There is two way of communication
• Connection-oriented for reliable transport to occur, a device that wants to establish a connection oriented communication session with remote device this is called three way handshake once this process complete , the data transfer occur
Some essential services
• Segmentation and sequencing – data is segmented into smaller pieces for transport. Each segment is assigned a sequence number, so that the receiving device can reassemble the data on arrival.
• Connection establishment – connections are established, maintained, and ultimately terminated between devices.
• Acknowledgments – receipt of data is confirmed through the use of acknowledgments. Otherwise, data is retransmitted, guaranteeing delivery.
• Flow control (or windowing) – data transfer rate is negotiated to prevent congestion.
The MAC sublayer controls access to the physical medium, serving as mediator if multiple devices are competing for the same physical link. Datalink layer technologies have various methods of accomplishing this - Ethernet uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD), and Token Ring utilizes a token.
• Segmentation and sequencing – data is segmented into smaller pieces for transport. Each segment is assigned a sequence number, so that the receiving device can reassemble the data on arrival.
• Connection establishment – connections are established, maintained, and ultimately terminated between devices.
• Acknowledgments – receipt of data is confirmed through the use of acknowledgments. Otherwise, data is retransmitted, guaranteeing delivery.
• Flow control (or windowing) – data transfer rate is negotiated to prevent congestion.
•Connectionless requires no connection before data is sent
There is two protocol use this services
• Transmission Control Protocol (TCP) – connection-oriented
• User Datagram Protocol (UDP) - connectionless
OSI Model - The Network Layer
The Network layer (Layer-3) controls internetwork communication
• Logical addressing – provides a unique address that identifies both the host, and the network that host exists on.
• Routing – determines the best path to a particular destination network, and then routes data accordingly.
OSI Model - The Data-Link Layer
While the Network layer is concerned with transporting data between networks, the Data-Link layer (Layer-2) is responsible for transporting data within a network.
The Network layer (Layer-3) controls internetwork communication
• Logical addressing – provides a unique address that identifies both the host, and the network that host exists on.
• Routing – determines the best path to a particular destination network, and then routes data accordingly.
OSI Model - The Data-Link Layer
While the Network layer is concerned with transporting data between networks, the Data-Link layer (Layer-2) is responsible for transporting data within a network.
The MAC sublayer controls access to the physical medium, serving as mediator if multiple devices are competing for the same physical link. Datalink layer technologies have various methods of accomplishing this - Ethernet uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD), and Token Ring utilizes a token.
The Data-link layer packages the higher-layer data into frames, so that the data can be put onto the physical wire. This packaging process is referred to as framing or encapsulation.
The encapsulation type will vary depending on the underlying technology.
Common Data-link layer technologies include following:
• Ethernet – the most common LAN data-link technology
• Token Ring – almost entirely deprecated
• FDDI (Fiber Distributed Data Interface)
• 802.11 Wireless
• Frame-Relay
• ATM (Asynchronous Transfer Mode)
• Ethernet – the most common LAN data-link technology
• Token Ring – almost entirely deprecated
• FDDI (Fiber Distributed Data Interface)
• 802.11 Wireless
• Frame-Relay
• ATM (Asynchronous Transfer Mode)
OSI Model - The Physical Layer
The Physical layer (Layer-1) controls the signaling and transferring of raw bits onto the physical medium. The Physical layer is closely related to the Data-link layer, as many technologies (such as Ethernet) contain both datalink and physical functions.
The Physical layer provides specifications for a variety of hardware:
• Cabling
• Connectors and transceivers
• Network interface cards (NICs)
• Wireless radios
• Hubs
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