Which tcp/ip model layer is responsible for providing the best path through the network
In computer science, the concept of network layers is a framework that helps to understand complex network interactions. There are two models that are widely referenced today: OSI and TCP/IP. The concepts are similar, but the layers themselves differ between the two models. While TCP/IP is the newer model, the Open Systems Interconnection (OSI) model is
still referenced a lot to describe network layers. The OSI model was developed by the International Organization for Standardization. There are 7 layers: People have come up with tons of mnemonic devices to memorize the OSI network layers. One popular mnemonic, starting with Layer 7, is “All People Seem To Need Data Processing.” But one that I’m partial to, which starts with Layer 1, is “Please Do Not Throw Sausage Pizza Away.” The TCP/IP model is a more concise framework, with only 4 layers: One mnemonic device for the TCP/IP model is “Armadillos Take In New Ants.” Download our whitepaper to see how the Plixer NPMD platform helps NetOps teams monitor network and application performance at the perimeter and interior, while also detecting abnormalities
that impact network performance, scalability, and availability. Network Layers and FunctionsFor the OSI model, let’s start at the top layer and work our way down.
The TCP/IP model, sometimes referred to as a protocol stack, can be considered a condensed version of the OSI model.
How Network Layers WorkAs we walk through an example, keep in mind that the network layers models are not strictly linear. One layer doesn’t finish its processes before the next one begins. Rather, they work in tandem. Application, Presentation, and Session LayersLet’s suppose you’re using Skype on a laptop. You’re messaging your friend, who’s using Skype on their phone from a different network. Skype, as a network-connected application, uses Layer 7 (Application) protocols like Telnet. If you send your friend a picture of your cat, Skype would be using the File Transfer Protocol (FTP). Layer 6 (Presentation) receives application data from Layer 7, translates it into binary, and compresses it. When you send a message, Layer 6 encrypts that data as it leaves your network. Then it decrypts the data when your friend receives it. Applications like Skype consist of text files and image files. When you download these files, Layer 5 (Session) determines which data packets belong to which files, as well as where these packets go. Layer 5 also establishes, maintains, and ends communication between devices. Transport and Network LayersLayer 4 (Transport) receives data from Layer 5 and segments it. Each segment, or data unit, has a source and destination port number, as well as a sequence number. The port number ensures that the segment reaches the correct application. The sequence number ensures that the segments arrive in the correct order. This layer also controls the amount of data transmitted. For example, your laptop may be able to handle 100 Mbps, whereas your friend’s phone can only process 10 Mbps. Layer 4 can dictate that the server slow down the data transmission, so nothing is lost by the time your friend receives it. But when your friend sends a message back, the server can increase the transmission rate to improve performance. Lastly, Layer 4 performs error-checking. If a segment of data is missing, Layer 4 will re-transmit that segment. TCP and UDP are both very well-known protocols, and they exist at Layer 4. TCP favors data quality over speed, whereas UDP favors speed over data quality. Layer 3 (Network) transmits data segments between networks in the form of packets. When you message your friend, this layer assigns source and destination IP addresses to the data segments. Your IP address is the source, and your friend’s is the destination. Layer 3 also determines the best paths for data delivery. Data Link and Physical LayersLayer 2 (Data Link) receives packets from Layer 3. Whereas Layer 4 performs logical addressing (IPv4, IPv6), Layer 2 performs physical addressing. It adds sender and receiver MAC addresses to the data packet to form a data unit called a frame. Layer 2 enables frames to be transported via local media (e.g. copper wire, optical fiber, or air). This layer is embedded as software in your computer’s Network Interface Card (NIC). In short, Layer 2 allows the upper network layers to access media, and controls how data is placed and received from media. Hardware—the things you can actually physically touch—exist at Layer 1 (Physical). This layer converts the binary from the upper layers into signals and transmits them over local media. These can be electrical, light, or radio signals; it depends on the type of media used. When your friend receives the signals, they’re decapsulated, or translated back into binary and then into application data so your friend can see your message. In ConclusionThis is a lot to absorb! Essentially, network layers help us understand how data moves from something human-readable, to computer-readable, to a transmitted signal, and back again. To learn more about networking, check out some of our other blogs:
AlienorAlienor is a technical writer at Plixer. She especially enjoys writing about the latest infosec news and creating guides and tips that readers can use to keep their information safe. When she’s not writing, Alienor spends her time cooking Japanese cuisine, watching movies, and playing Monster Hunter. In what layer in the TCP IP reference model determines the best path through the network?Layer 3 (Network) transmits data segments between networks in the form of packets. When you message your friend, this layer assigns source and destination IP addresses to the data segments. Your IP address is the source, and your friend's is the destination. Layer 3 also determines the best paths for data delivery.
Which TCP IP network model is responsible for IP addresses?The Internet Layer of the TCP/IP model aligns with the Layer 3 (Network) layer of the OSI model. This is where IP addresses and routing live.
Which is the most important layer of the TCP IP and why?At the top of the TCP/IP protocol architecture is the Application Layer. This layer includes all processes that use the Transport Layer protocols to deliver data. There are many applications protocols.
What are the 4 layers of TCP IP?4 The TCP/IP Protocol Stack is made up of four primary layers: the Application, Transport, Network, and Link layers (Diagram 1).
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