Open System Interconnection

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Open System Interconnection
Open System Interconnection (ISO) model was developed by the International Standards Organization. The model has seven layers. Layer 5-7 are the upper layers while 1-7 are the lower layers (Beal 1). Application or layer seven supports end-user and application processes. Presentation or layer six “provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa” (Beal 1). Session or layer five is responsible for establishing, managing, and termination of connections between applications. Transport or layer four is responsible for flow control and end-to-end error recovery, and thus it provides transparent data transfer between hosts or end systems. Network or layer three is responsible for the transmission of data from node to node by providing routing and switching technologies. Data link or layer two “furnish transmission protocol knowledge and management and handles errors in the physical layer, flow control, and frame synchronization” (Beal 1). Finally, physical or layer one carries the bit-stream via the network at the mechanical and electrical level. Notably, they interact in the sense that while layers 5-7 contains application level data, layers 1-4 are responsible for moving data around. I believe the layers are inter-connected and therefore cannot function if a layer is missing.
Transport layer: Like the transport layer in ISO, the transport layer in TCP/IP is responsible for end-to-end error-free data delivery.

Other functions of the layer include the following; provision of reliable control, verification, flow control, and error checking; provides the users to the underlying network with an interface; and facilitates conversation in the communicating hosts. Protocols used in this layer include Stream Control Transmission Protocol, User Datagram Protocol, and Transmission Control Protocol (Raj 1).
Application Layer: Specific functions of this layer include among others directory services, mail services, file transfer, access, and management and network virtual terminal.

Works Cited
Beal, Vangie. “The 7 Layers of The OSI Model – Webopedia Study Guide”. Webopedia.Com, 2018, https://www.webopedia.com/quick_ref/OSI_Layers.asp. Accessed 5 Dec 2018.
Raj, Rishi. “The Transport Layer In TCP/IP Model”. Tutorialspoint.Com, 2018, https://www.tutorialspoint.com/The-Transport-Layer-in-TCP-IP-Model. Accessed 5 Dec 2018.