OSI Model Flashcards
What is the goal of the OSI model?
It’s goal is the interoperability of diverse communications systems with standard protocols.
What is OSI?
The Open Systems Interconnection Model defines a networking framework that illustrates how information moves from an application program running on one networked computer to an application program running on another networked computer.
How many layers are in the OSI Model?
There are 7 layers in the OSI Model.
What is layer 1 of the OSI Model?
Layer 1 is the PHYSICAL layer. The PDU is BITS.
This layer conveys the bit stream - electrical impulse, light or radio signal — through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects. Fast Ethernet, RS232, and ATM are protocols with physical layer components.
What is layer 2 of the OSI Model?
Layer 2 is the DATA LINK layer. The PDU is FRAME.
At this layer, data packets are encoded and decoded into bits. It furnishes transmission protocol knowledge and management and handles errors in the physical layer, flow control and frame synchronization. The data link layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. The LLC layer controls frame synchronization, flow control and error checking.
What is layer 3 of the OSI Model?
Layer 3 is the NETWORK layer. The PDU is PACKET.
This layer provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node. Routing and forwarding are functions of this layer, as well as addressing, internetworking, error handling, congestion control and packet sequencing.
What is layer 4 of the OSI Model?
Layer 4 is the TRANSPORT layer.
The PDU is segment.
This layer provides transparent transfer of data between end systems, or hosts, and is responsible for end-to-end error recovery and flow control. It ensures complete data transfer.
What is layer 5 of the OSI Model?
Layer 5 is the SESSION layer. The PDU is DATA.
This layer establishes, manages and terminates connections between applications. The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at each end. It deals with session and connection coordination.
What is layer 6 of the OSI Model?
Layer 6 is the PRESENTATION layer. The PDU is DATA.
This layer provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. The presentation layer works to transform data into the form that the application layer can accept. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer.
What is layer 7 of the OSI Model?
Layer 7 is the APPLICATION layer. The PDU is DATA.
This layer supports application and end-user processes. Communication partners are identified, quality of service is identified, user authentication and privacy are considered, and any constraints on data syntax are identified. Everything at this layer is application-specific. This layer provides application services for file transfers, e-mail, and other network software services. Telnet and FTP are applications that exist entirely in the application level. Tiered application architectures are part of this layer.
What are the 7 layers of the OSI Model?
1 - Physical 2 - Data Link 3 - Network 4 - Transport 5 - Session 6 - Presentation 7 - Application
What does PDU stand for?
Protocol Data Unit
