Modelo osi wifi

Once you learn the OSI model, you will be able to further understand and appreciate this glorious entity we call the Internet, as well as be able to troubleshoot networking issues with greater fluency and ease. However, you will need:. Here are some common networking terms that you should be familiar with to get the most out of this article.

A node is a physical electronic device hooked up to a network, for example a computer, printer, router, and so on. Nodes may be set up adjacent to one other, wherein Node A can connect directly to Node B, or there may be an intermediate node, like a switch or a router, set up between Node A and Node B. Typically, routers connect networks to the Internet and switches operate within a network to facilitate intra-network communication.

Learn more about hub vs. For the nitpicky among us yep, I see you , host is another term that you will encounter in networking. I will define a host as a type of node that requires an IP address.

All hosts are nodes, but not all nodes are hosts. Please Tweet angrily at me if you disagree. A protocol is a mutually agreed upon set of rules that allows two nodes on a network to exchange data.

While anyone can create a protocol, the most widely adopted protocols are often based on standards published by Internet organizations such as the Internet Engineering Task Force IETF. A network is a general term for a group of computers, printers, or any other device that wants to share data. Learn more here. Topology describes how nodes and links fit together in a network configuration, often depicted in a diagram.

Here are some common network topology types:. A network consists of nodes, links between nodes, and protocols that govern data transmission between nodes. A layer is a way of categorizing and grouping functionality and behavior on and of a network. In the OSI model, layers are organized from the most tangible and most physical, to less tangible and less physical but closer to the end user. Each layer abstracts lower level functionality away until by the time you get to the highest layer.

All the details and inner workings of all the other layers are hidden from the end user. For example, Ethernet, Layer 1 is the physical layer. I encourage readers to learn more about each of these categories:.

A bit the smallest unit of transmittable digital information. Bits are binary, so either a 0 or a 1. Bytes, consisting of 8 bits, are used to represent single characters, like a letter, numeral, or symbol. Bits are sent to and from hardware devices in accordance with the supported data rate transmission rate, in number of bits per second or millisecond and are synchronized so the number of bits sent and received per unit of time remains consistent this is called bit synchronization.

The way bits are transmitted depends on the signal transmission method. Nodes can send, receive, or send and receive bits. If they can only do one, then the node uses a simplex mode. If they can do both, then the node uses a duplex mode. The original Ethernet was half-duplex. Full-duplex Ethernet is an option now, given the right equipment. It defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating physical links between network devices.

Fun fact: deep-sea communications cables transmit data around the world. Layer 2 is the data link layer. Layer 2 defines how data is formatted for transmission, how much data can flow between nodes, for how long, and what to do when errors are detected in this flow. Jumbo frames exceed the standard MTU, learn more about jumbo frames here. The Data Link Layer allows nodes to communicate with each other within a local area network. The foundations of line discipline, flow control, and error control are established in this layer.

Layer 3 is the network layer. This is where we send information between and across networks through the use of routers. Instead of just node-to-node communication, we can now do network-to-network communication. They move data packets across multiple networks.

The data unit on Layer 3 is the data packet. Typically, each data packet contains a frame plus an IP address information wrapper. In other words, frames are encapsulated by Layer 3 addressing information. The data being transmitted in a packet is also sometimes called the payload.

While each packet has everything it needs to get to its destination, whether or not it makes it there is another story. More on data transport protocols on Layer 4. Once a node is connected to the Internet, it is assigned an Internet Protocol IP address, which looks either like Routers use IP addresses in their routing tables.

Many answers to Layer 3 questions will require the use of command-line tools like ping , trace , show ip route , or show ip protocols. Learn more about troubleshooting on layer here. The Network Layer allows nodes to connect to the Internet and send information across different networks.

Layer 4 is the transport layer. This where we dive into the nitty gritty specifics of the connection between two nodes and how information is transmitted between them. It builds on the functions of Layer 2 - line discipline, flow control, and error control. This layer is also responsible for data packet segmentation, or how data packets are broken up and sent over the network. Unlike the previous layer, Layer 4 also has an understanding of the whole message, not just the contents of each individual data packet.

With this understanding, Layer 4 is able to manage network congestion by not sending all the packets at once. The data units of Layer 4 go by a few names. For TCP, the data unit is a packet.

For UDP, a packet is referred to as a datagram. TCP explicitly establishes a connection with the destination node and requires a handshake between the source and destination nodes when data is transmitted. The handshake confirms that data was received. If the destination node does not receive all of the data, TCP will ask for a retry. TCP also ensures that packets are delivered or reassembled in the correct order. Learn more about TCP here. UDP, a connectionless protocol, prioritizes speed over data quality.

If information is split up into multiple datagrams, unless those datagrams contain a sequence number, UDP does not ensure that packets are reassembled in the correct order. Learn more about UDP here. The combination of the IP address and the port number is called a socket. Learn more about sockets here. Learn more about the differences and similarities between these two protocols here.

The Transport Layer provides end-to-end transmission of a message by segmenting a message into multiple data packets; the layer supports connection-oriented and connectionless communication. Layer 5 is the session layer. This layer establishes, maintains, and terminates sessions. A session is a mutually agreed upon connection that is established between two network applications. Not two nodes! They were so Layer 4. So a session is a connection that is established between two specific end-user applications.

There are two important concepts to consider here:. Sessions may be open for a very short amount of time or a long amount of time. They may fail sometimes, too.

Depending on the protocol in question, various failure resolution processes may kick in. From here on out layer 5 and up , networks are focused on ways of making connections to end-user applications and displaying data to the user. The Session Layer initiates, maintains, and terminates connections between two end-user applications. It responds to requests from the presentation layer and issues requests to the transport layer. Layer 6 is the presentation layer.

This layer is responsible for data formatting, such as character encoding and conversions, and data encryption. The operating system that hosts the end-user application is typically involved in Layer 6 processes. This functionality is not always implemented in a network protocol. Layer 6 makes sure that end-user applications operating on Layer 7 can successfully consume data and, of course, eventually display it.

Learn more about character encoding methods in this article , and also here. These encryption protocols help ensure that transmitted data is less vulnerable to malicious actors by providing authentication and data encryption for nodes operating on a network.

True to its name, this is the layer that is ultimately responsible for supporting services used by end-user applications. Applications include software programs that are installed on the operating system, like Internet browsers for example, Firefox or word processing programs for example, Microsoft Word.

Applications can perform specialized network functions under the hood and require specialized services that fall under the umbrella of Layer 7. Electronic mail programs, for example, are specifically created to run over a network and utilize networking functionality, such as email protocols, which fall under Layer 7. Applications will also control end-user interaction, such as security checks for example, MFA , identification of two participants, initiation of an exchange of information, and so on.

The Physical layer, or PHY, is the medium through which communication is effected. It is at this layer the transceiver is controlled to access the medium. We are primarily concerned with the wireless medium. Unlike a bounded, wired medium, WLANs operate "over the air" and are subject to an entirely different set of rules for accessing and controlling the medium.

For instance, wired networks have the ability to detect and mitigate data collisions; wireless networks cannot detect collisions, instead, elaborate protocols are in place to allow access and control of the medium and to avoid collisions. Wireless networks are also subject to unintentional interference and intentional disruptions. Wired networks are relatively difficult to hack into while wireless networks can be casually hacked by anyone with a wireless card within range of an access point.

These issues have provided developers with significant challenges to overcome to ensure that WLANs are reliable and secure. The LLC receives an IP packet from the Network layer above it and encapsulates the data with addressing and control information.

This packet, now called a frame, is passed to the MAC, which modifies the addressing and control information in the frame header to ensure the data is in the proper form for application to the Physical layer. The process is reversed at the receiving end. Upon successfully receiving the transmitted data, it is demodulated and the resulting frame is passed to the receiving MAC. The frame header is examined to determine if it is the intended address; if it is, then the MAC data is stripped off and passed to the LLC, which then examines the upper-level addressing data in its header.

It strips off its data and passes the packet to the Network layer, which performs the proper routing to the destination on the local network. This all happens within an average time span of milliseconds, unless QoS protocols are in play, in which case the processing time is significantly reduced.

Unfortunately, congested networks will cause excessive arbitration for control of the medium, resulting in latency and extended transaction times. Capano, owner and president, Diversified Technical Services Inc. Control Engineering has a wireless page. Wireless Wi-Fi and the OSI model Industrial wireless tutorials: The Open Systems Interconnection OSI model is a conceptual model used to organize the various functions of data communications by segregating the distinct functions into a seven-layer model from the Physical layer.

Learn how the OSI model relates to industrial wireless communications. By Daniel E. Capano September 18, The Open Systems Interconnection Model Layer name Description 7 — Application Graphical user interface; primary user interface with communication system. Controls the Physical layer. Gray Solutions. Automation Ready Panels. By using this website, you agree to our use of cookies.

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