The OSI Model questions answered 100% correct passed!

The OSI Model questions answered 100% correct passed!What is the OSI Model? The OSI Model is a universal set of specifications that enable computer platforms across the world to communicate openly with each other. What does OSI stand for? OSI stands for Open System Interconnection It is used to divide networking architecture into seven different layers. (the word architecture is used to describe a networks infrastructure because like a building, networks are comprised of many integrated elements: cabling, servers, applications, NIC's and many other elements) . These layers are from the top to the bottom: - Application - Presentation - Session - Transport - Network - Data Link - Physical Each layer has its own set of functions (chores that it is responsible for) and interacts with the layers directly above or below. Who designed the OSI Model? ISO (International Organization for Standards) The reason that ISO is used instead of IOS is that ISO is not supposed to be an acronym for International Organization for Standards. In fact ISO is the Greek word for "equal". So who is the ISO and what do they do? The ISO is a collection of Standards organizations that represent 130 countries. Its headquarters are in Geneva Switzerland ISO's goal is to establish international technological standards to facilitate global exchange of information and barrier-free trade. THE PHYSICAL LAYER The Physical Layer also referred to as Layer 1 is where everything connects together and comprises of devices that do not translate the information flowing on the network, but only pass it on. The Physical Layer consists of things like: The wires in the network, which could be Ethernet cables or fiber optic cables Other technology for sending signals such as infrared or micro wave The connectors at the ends of the wires (used to join devices together) Repeaters (devices that amplify any signal coming in without checking the signal) Hubs (devices used to join multiple computers together) Devices that control the speed at which information is sent so that most of the information makes it to its destination. These devices know the speed of the networks they are connected to as in 10 Mbps or 100 Mbps and slow down or speed up the packets on the network. Without these network devices it would be like pouring water in a funnel. If you pour too fast it will overflow and the water that overflows does not make it to the desired location) Basically the Physical Layer provides the hardware means of sending and receiving data on a carrier. THE DATA LINK LAYER The Data Link Layer also referred to as Layer 2 is the layer responsible for breaking raw data into smaller chunks called frames. Frames from particular nodes are usually the same size and used for timing purposes just like frames in a film. Layer 2/Data Link Layer is responsible for making sure the data reaches the desired destination. Layer 2/Data Link Layer is also responsible for making sure data flows at the right speed. Frame A frame is a structured package for moving data similar to how a train is configured to move cargo. Like the train that has the Engine at the front, cargo in the middle, and the caboose at the end, a data frame also has different components. The Data Link Layer consists of things like: As mentioned before The Data Link layer interacts with both the Layer below it (The Physical Layer) and the Layer above it (The Network Layer) The Data Link Layer provides the control information (information that it can use to make sure the whole frame is transmitted) The Data Link Layer breaks the Source Data into transmittable frames The Data Link Layer provides the error checking information (information that network can use to make sure the whole frame was delivered) One way that this is done is by size. The Data Link Layer knows that a full Data Frame has 500 (fictitious size) bits of information. If the receiving device reads 500 bits then it assumes all the Frame is present, otherwise it will respond back to the sending device to please resend. MAC Addresses The Data Link Layer uses the Destination and Source MAC Addresses A MAC Address (Media Access Control) is the unique identifier (address) that every NIC (Network Interface Card) in the world has There are 248 or 281,474,976,710,656 different combinations. THE NETWORK LAYER The Network Layer also referred to as Layer 3 is primarily responsible for getting packets from the source node (computer) to the destination node using the quickest know route. It does this by using the IP address (Layer 3 protocol) together with the physical MAC address (Layer 2) of both nodes