protocol reference model of osi
TRANSCRIPT
![Page 1: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/1.jpg)
Protocol Reference Model of OSI
![Page 2: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/2.jpg)
Introduction to the OSI layer How OSI was created and why Comparison with TCP/IP Layers : Application layer Presentation layer Session layer Transport layer Network layer Data link layer Physical layer Conclusion Resources
![Page 3: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/3.jpg)
Open Systems Interconnection (OSI) Each layer support the layers above it and
offers services to the layers below Each layer performs unique and specific
task A layer only has knowledge of its neighbour
layers only A layer service is independent of the
implementation
![Page 4: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/4.jpg)
An attempt for a framework for developing networking technologies
OSI became a tool for explaining the Networking in general
Before OSI was created people created their Software/Hardware as they wanted it to be. There was not any compatibility. Now OSI is used as a rule set for all vendors to create their Software/Hardware by using the standards.
![Page 5: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/5.jpg)
Protocol Reference Model of OSI
II OSI Overview
1. OSI - layered framework for the design of network systems that allows communication across all types of computer systems.
2. The OSI 7 Layers. ( Brief functional overview. )
3. Vertical and horizontal
communication between the layers using interfaces. (defines what information and services should the layer provide to the layer above it. )
![Page 6: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/6.jpg)
Each layer contains a logical grouping of functions
Each function receive an input(one or more) and produces an output
![Page 7: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/7.jpg)
Protocol Reference Model of OSII History 1. The need for standardization
- many vendors, no interoperability - no common framework 2. ISO and CCITT came up withOSI (Open System Intercommunication) in
1984.
3. OSI Protocol Suite – unaccepted by vendors and users. (TCP won)
4. OSI – a standard, which allows
communication between different systems without requiring changes to the logic of the underlying hardware and software.
![Page 8: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/8.jpg)
Protocol Reference Model of OSILayer abstraction and the path of the message
![Page 9: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/9.jpg)
Protocol Reference Model of OSI
OSI Overview
4. Data Encapsulation a) PDU conception – each protocol on the diff. layer has its own format.b) Headers are added while a packet is going down the stack at each layer. c) Trailers are usually added on the second layer.
![Page 10: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/10.jpg)
Pretty similar to OSI TCP/IP has less layers(four) Main difference in layers is after layer 4
![Page 11: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/11.jpg)
![Page 12: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/12.jpg)
Applications and Services run on it Enables human network to interface the underlying data
network Applications on that layer (E-mail clients, web browsers, Chats,
etc.) – top-stack applications (As people are on the top of the stack)
Applications provide people with a way to create message Application layer services establish an interface to the network Protocols provide the rules and formats that govern how data is
treated Protocols on the destination and the host must match
![Page 13: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/13.jpg)
Protocol Reference Model of OSI
III The OSI Layers7. Application Layer
◦ Provides user interfaces and support for services
◦ Resource sharing and device redirection
◦ Remote file access◦ Remote printer access◦ Inter-process communication◦ Network management◦ Directory services◦ Electronic messaging (such
as mail)◦ Network virtual terminals
![Page 14: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/14.jpg)
Coding and conversion of Application layer data to ensure that data from the source device can be interpreted by the appropriate application on the destination device.
Compression of the data in a manner that can be decompressed by the destination device.
Encryption of the data for transmission and the decryption of data upon receipt by the destination.
This is the layer at which application programmers consider data structure and presentation
Examples: GIF, JPEG, TIFF, etc. Sometimes n distinction is made between the presentation and
application layers. For example http/https. HTTP is generally regarded as an application layer protocol although it has Presentation layer aspects such as the ability t identify character encoding for roper conversion
![Page 15: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/15.jpg)
Protocol Reference Model of OSI
The OSI Layers6. Presentation Layer
◦ Translation (connects different computer systems)
◦ Compression (transmission efficiency)
◦ Encryption (SSL security)
![Page 16: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/16.jpg)
Functions at this layer create and maintain dialogs between source and destination applications
Authentication Permissions Session Restoration (Checkpoint or
recovery)
![Page 17: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/17.jpg)
Protocol Reference Model of OSI
The OSI Layers5. Session Layer
◦ Session establishment, maintenance and termination (Deciding who sends, and when.)
◦ Session support (security, name recognition, logging )
![Page 18: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/18.jpg)
Tracking the individual communication between applications on the source and destination hosts
Segmenting data and managing each piece Reassembling the segments into streams of application data Identifying the different applications Conversation Multiplexing Segments Connection-oriented conversations Reliable delivery Ordered data reconstruction Flow control TCP – Web Browser UDP – Video Streaming Applications
![Page 19: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/19.jpg)
Protocol Reference Model of OSI
The OSI Layers4. Transport Layer
◦ Connectionless and connection-oriented services
◦ Process-Level Addressing◦ Multiplexing and
Demultiplexing ◦ Segmentation, Packaging
and Reassembly ◦ Connection Establishment,
Management and Termination
◦ Acknowledgments and Retransmissions
◦ Flow Control
![Page 20: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/20.jpg)
Addressing (IPV4) Encapsulation (Inserts a header with source
and destination IPs) Routing (Move a packet over the Internet) Decapsulation (Open the packet and check
the destination host) IP is connectionless
![Page 21: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/21.jpg)
Protocol Reference Model of OSI
The OSI Layers3. Network Layer
◦ Logical Addressing ◦ Routing (where the packet is
destinated to) ◦ Datagram Encapsulation ◦ Fragmentation and
Reassembly (handling too big packets )
◦ Error Handling and Diagnostics ( using status messages for example )
![Page 22: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/22.jpg)
Protocol Reference Model of OSIEnd to end packet delivery
![Page 23: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/23.jpg)
It is the role of the OSI Data Link layer to prepare Network layer packets for transmission and to control access to the physical media.
Allows the upper layers to access the media using techniques such as framing
Controls how data is placed onto the media and is received from the media using techniques such as media access control and error detection
Frame - The Data Link layer PDU Node - The Layer 2 notation for network devices connected to a
common medium Media/medium - The physical means for the transfer of information
between two nodes Network - Two or more nodes connected to a common medium The Data Link layer is responsible for the exchange of frames between
nodes over the media of a physical network.
![Page 24: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/24.jpg)
Protocol Reference Model of OSI
The OSI Layers2. Data Link Layer2.1. Logical Link Control (LLC )
◦ Establishment and control of logical links between local devices on a network.
2.2. Media Access Control (MAC) ◦ The procedures used by devices
to control access to the network medium.
◦ • Frame sequencing • Frame acknowledgment • Addressing• Frame delimiting• Frame error checking• PDU: frame
![Page 25: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/25.jpg)
The role of the Physical layer is to encode the binary digits that represent Data Link layer frames into signals and to transmit and receive these signals across the physical media that connect network devices.
Copper cable Fiber Wireless
![Page 26: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/26.jpg)
Protocol Reference Model of OSI
The OSI Layers1. Physical Layer
• Definition of Hardware Specifications (of cables, connectors, wireless radio transceivers, network interface cards )
• Encoding and Signaling (bit representation)
• Data Transmission and Reception (half duplex, full duplex )
• Topology and Physical Network Design (mesh, ring, bus)
• PDU: bit
![Page 27: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/27.jpg)
Protocol Reference Model of OSI
OSI Summary
![Page 28: Protocol Reference Model of OSI](https://reader031.vdocuments.us/reader031/viewer/2022012402/586b87171a28ab55088ba322/html5/thumbnails/28.jpg)
The way people learn Networking A standard for software A standard for hardware Seven layers architecture Each layer independent on the others Similar to TCP/IP(TCP/IP explained) OSI is used as a model for developing
network aware applications(Here I mean that people use its structure to model software)