OSI and TCP/IP PART III

OSI LAYER

The Open Systems Interconnection model (OSI model) is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar communication functions are grouped into logical layers. An instance of a layer provides services to its upper layer instances while receiving services from the layer below.

For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of that path. Two instances at one layer are connected by a horizontal connection on that layer.

OSI and TCP/IP PART II

Transport Layer

• The Transport Layer's responsibilities include end-to-end message transfer capabilities independent of the underlying network, along with error control, segmentation, flow control, congestion control, and application addressing (port numbers). End to end message transmission or connecting applications at the transport layer can be categorized as either connection-oriented, implemented in Transmission Control Protocol (TCP), or connectionless, implemented in User Datagram Protocol (UDP).

• The Transport Layer can be thought of as a transport mechanism, e.g., a vehicle with the responsibility to make sure that its contents (passengers/goods) reach their destination safely and soundly, unless another protocol layer is responsible for safe delivery.

OSI and TCP/IP PART I

The TCP/IP model is a description framework for computer network protocols created in the 1970s by DARPA, an agency of the United States Department of Defense. It evolved from ARPANET, which was the world's first wide area network and a predecessor of the Internet. The TCP/IP Model is sometimes called the Internet Model or the DoD Model.

The TCP/IP model, or Internet Protocol Suite, describes a set of general design guidelines and implementations of specific networking protocols to enable computers to communicate over a network. TCP/IP provides end-to-end connectivity specifying how data should be formatted, addressed, transmitted, routed and received at the destination. Protocols exist for a variety of different types of communication services between computers.

DISCUSSION PROBLEM

Problem no 1

The Meaning Of  Data Transmission

Transmission is the movement of information over a telecommunications medium.  attention to making the transmission channel used to transmit information, as well as to ensure that the information can be accurately and reliably.

So, data transmission is a movement of information over a telecommunications medium, to share information accurately and reliably

NETWORK APPLICATION

Network Application

·         DNS – Domain Name Server

DNS be created to will overcome name conflict host that often will happen when name host will along with address ip- will not be regulated according to centralization. problem DNS is nomenclature pattern invention based on domain has hierarchy and database system invention that distributing for this nomenclature pattern implementation.