Application Security Application Delivery Data Security. Erez Hasson , Bruce Lynch. Application Delivery Application Security. Application Delivery. Pamela Weaver. Bruce Lynch. Eyal Gur. Erez Hasson. DDoS Mitigation Grainne McKeever. Latest Articles. App Security Edge Security DDoS Essentials. Now the reasons ISO-OSI model says to group together similar functions, here we will be explaining why exactly we need different layer for efficient routing.
Every layer can implement similar functions and every layer can perform some specific tasks. Now as every layer is performing their some specific task so we are cornered about our layer only and not in how the under-lying layer is implemented so its kind of Abstraction. In simple words, we can say we are concerned only about what function we get from a layer and not how we get that. It helps in Testing , it means each layer can be tested separately thus it would be easy to find errors if present any.
Application Layer 2. Presentation Layer 3. Session Layer 4. Transport Layer 5. Network Layer 6. Data link Layer 7. Physical Layer The first 3 layers are usually for intended user-specific. Physical Layer : It deals with how our data, which are in bit are going to be get converted into be various kinds of signals and how these are to be transported among routers and hosts.
For example, when a web application makes a request to a web server, it typically uses port number 80, because this is the default port assigned to web applications. Many applications have default ports assigned. It also performs sequencing and reassembling of the segmented data.
The functions of the transport layer are : Segmentation and Reassembly: This layer accepts the message from the session layer, breaks the message into smaller units.
Each of the segments produced has a header associated with it. The transport layer at the destination station reassembles the message. Service Point Addressing: In order to deliver the message to the correct process, the transport layer header includes a type of address called service point address or port address.
Thus by specifying this address, the transport layer makes sure that the message is delivered to the correct process. This type of transmission is reliable and secure. Connectionless service: It is a one-phase process and includes Data Transfer. In this type of transmission, the receiver does not acknowledge receipt of a packet. This approach allows for much faster communication between devices. Connection-oriented service is more reliable than connectionless Service.
It is a part of the OS and communicates with the Application Layer by making system calls. Session Layer Layer 5 : This layer is responsible for the establishment of connection, maintenance of sessions, authentication, and also ensures security. The functions of the session layer are :. Skip to content. Change Language.
The layers are abstracted in such a way that each layer believes it is communicating with the same layer on the other computer. In reality, each layer communicates only with adjacent layers on the same machine. Layer0, which is not officially a layer in the OSI model, is commonly used to define the underlying transmission media, such as cables or fiber, that interconnect each of the computers on the network.
Layer0 is known as the Media Layer. OSI stands for Open Systems Interconnection reference model is a logical model for how different pieces of software, hardware, drivers, and applications all work together to allow computers to communicate over a network.
International Standards give state of the art specifications for products, services and good practice, helping to make industry more efficient and effective. Developed through global consensus, they help to break down barriers to international trade, It is headquartered in Geneva, Switzerland. The Open System Interconnection OSI model is conceptual model that characterizes and standardizes the internal functions of a communication system The model groups similar communication functions into one of seven logical layers.
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