Open Systems Interconnections Protocol
The Open Systems Interconnections Protocol is a model used for international means. This model allows communication between various hardware systems and software systems throughout the world regardless of the network architecture that is present. The internet itself and other various communication methods would become extremely limited by comparison without any similar type of protocol in place.
The Open Systems Interconnections Model is mainly for computers and devices that are communicating over a network and to other networks, but can also be implemented on a local scale even if only between two devices. Note: the purpose of the creation of this protocol was not for local means but for international connectivity. It would not have been required to create such a protocol in the first place since when this protocol was being initiated many local networks did already exist.
The International Organization for Standardization with the help of the Telecommunications Standards Sector of the International Telecommunications Union is who designed the Open Systems Interconnections Models. These models were initiated in 1977. In all actuality, the Open Systems Interconnections Model contains seven levels. The First level is the Physical Level, which is comprised of physical electronic, and/or optical signals that when comprised, produce bit streams: this level is mainly present in hardware before the bit stream (packet) connects with another computer or device. The Second level is the Data Link Level: this level provides node to node transfer and adds error checking to the bit stream (packet) before it enters the data link line. The Third level is the Routing & Relaying [networking] Level which provides a path of transfer for the bit stream (packet), and gives it an address. The Fourth level [transport] is the Reliable Transfer Of Data Level which checks for errors to ensure that a reliable transport of the bit stream (packet(s)) is made. The Dialog Coordination Level is level 5; this level adds traffic flow information to signify when the bit stream (packet(s)) is sent. Level 6 is the Data Representation Level that adds formatting and encryption to the bit stream (packet(s)) while also incorporating information for information display methods. Level Seven is the Applications Level which originates a request (applications and programs do this all the time, one example could be for an application on a cellular device to request an internet connection so that a calculation can be made, determined, verified, or created.
X.25 can utilize up over 4000 channels on a single physical channel. This technology was popular in the 1980s for ATMs: because an ATM has to check balances and ensure funds are present, internet connections and protocols were required. With X.25 Data Packets hold a minimum of 128 octets of data. Overall this was a very successful technology protocol; but not without disadvantages. The actual...