1.The OSI, or Open System Interconnection, model defines a networking framework to implement protocols in seven layers.
2.Developed by ISO in 1984.
3.The core of this standard is the OSI Reference Model, a set of seven layers that define the different stages that data must go through to travel from one device to another over a network.
4.These 7 layers further divide tasks of moving the data across the network into subtasks and hence complete one communication cycle between two computers or two network devices.
5.Each layer is assigned a task and the task is completed independently.
Seven layers are-
7. Application Layer:
- It defines the interfaces for communication and data transfer.
- This layer supports application and end-user processes.
- This layer also provides and support services such as job transfer, handles network access, email, supports user application.
- Layer 7 Application examples include WWW browsers, NFS, SNMP, Telnet, HTTP, FTP
6. Presentation Layer:
- Layer 6 takes the data provided by the Application layer and converts it into a standard format that the other layers can understand.
- Also responsible for protocol conversion, encryption, decryption and data compression.
- Best layer for cryptography.
2.Developed by ISO in 1984.
3.The core of this standard is the OSI Reference Model, a set of seven layers that define the different stages that data must go through to travel from one device to another over a network.
4.These 7 layers further divide tasks of moving the data across the network into subtasks and hence complete one communication cycle between two computers or two network devices.
5.Each layer is assigned a task and the task is completed independently.
Seven layers are-
7. Application Layer:
- It defines the interfaces for communication and data transfer.
- This layer supports application and end-user processes.
- This layer also provides and support services such as job transfer, handles network access, email, supports user application.
- Layer 7 Application examples include WWW browsers, NFS, SNMP, Telnet, HTTP, FTP
6. Presentation Layer:
- Layer 6 takes the data provided by the Application layer and converts it into a standard format that the other layers can understand.
- Also responsible for protocol conversion, encryption, decryption and data compression.
- Best layer for cryptography.
- Layer 6 Presentation examples include encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG, MPEG, MIDI.
5. Session Layer:
- The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at each end.
- It deals with session and connection coordination.
- Examples-interactive logins and file transfer session.
- Layer 5 Session examples include NFS, NetBios names, RPC, SQL.
4. Transport Layer:
- It manages end to end message delivery in a network.
- Also provides error checking and hence guaranties that no duplicate or errors are occuring in the data transfer across the network.
- This layer maintains flow control of data and provides for error checking and recovery of data between the devices.
- The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) of the Internet Protocol Suite are commonly categorized as layer-4 protocols within OSI.
- Layer 4 Transport examples include SPX, TCP, UDP.
3. Network Layer:
- The way that the data will be sent to the recipient device is determined in this layer.
- This layer provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node.
- The layer routes the packets according to the unique network address.
- Layer 3 Network examples include AppleTalk ,OSPF,RIP, IP, IPX.
2. Datalink Layer:
- The data link layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer.
- The MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. The LLC layer controls frame synchronization, flow control and error checking.
- Layer 2 Data Link examples include PPP, FDDI, ATM, IEEE 802.5/ 802.2, IEEE 802.3/802.2, HDLC, Frame Relay.
1. Physical Layer:
- This layer conveys the bit stream - electrical impulse, light or radio signal .
- It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects. Fast Ethernet, RS232, and ATM are protocols with physical layer components.
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