Osi Seven Layer Model

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OSI Seven Layer Model
The Open System Interconnection model (OSI) defines internetworking in terms of a vertical stack of seven layers. The upper layers of the OSI model represent software that implements network services like encryption and connection management. The lower layers of the OSI model implement more primitive, hardware-oriented functions like routing, addressing, and flow control(Mitchell, 2011).The seven layers of the OSI model are - * Physical * DataLink * Network * Transport * Session * Presentation * Application
Physical Layer is the first layer of the OSI model and deals with the physical aspects of the media being used to transmit the data. This layer is also responsible for bit-level transmission between network nodes. Specification examples include Ethernet, 802.3, 802.5, and Fiber Distributed Data Interface.
Data Link Layer is the second layer of the OSI model and is responsible for ensuring there are data link connections between two network entities so that data can get across a specific medium and individual links. Examples of this layer include IEEE 802.3, IEEE 802.5, Token Ring, and Frame Relay.
Network Layer is the third layer of the OSI model and is responsible for the packet sequencing, congestion control, and error handling. This layer also provides paths for data to transfer through the network. At the Network layer routers began to operate. Examples of this layer include the use of Internetwork Protocol (IP) as its network layer interface. Packet Filtering and firewalls also operate at this layer of the OSI model and is developed to restrict unauthorized inward network access. Packet Filter is set up to control traffic flow between two networks by configured permissions like Allow, Deny, Block, and Encrypt. During the packet filter firewall the following characteristics are examined (…...

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