Mac Information In A Layer 2 Frame Is Intended For Which Osi Layer?

#Information In A Layer 2 Frame Is Intended For Which Osi Layer? Plus All The

In this article, we will cover all that, going even deeper to truly understand the data link layer. At the data link layer a lot of crucial tasks have to be handled, such as the detection of interferences, the delivery to the correct node if more nodes share access to the same media or the rules that allow a device to talk on the media or to wait for its turn. Even if this could seem simple at a first glance, at this layer protocols start to get involved. At the receiving end, the process is reversed.The data link layer is the one that allows the communication between two contiguous nodes, which are nodes having access to a common media (connected together either directly or via a shared media). The frame is then passed to the Physical layer, which puts the frame on to the medium using various techniques. The Network layer passes the data, now called a packet, or datagram, to the Data Link layer, which adds addressing data and control information to the datagram, creating a frame.

And it is present in any network device (otherwise the device wouldnвЂ™t be able to communicate at all), specifically in the Network Interface Card (NIC). Places information in the frame that identifies which network layer protocol is.Read More.Until now, we just talked about concepts, but in the end, that data link layer has to be implemented somewhere. Controls the NIC responsible for sending and receiving data on the physical medium. 2) Frequent Disconnection - no set time frame or Interval.Which two functions are performed at the MAC sublayer of the OSI data link layer (Choose two.) Provides a mechanism to allow multiple devices to communicate over a shared medium.

The CPU is the brain of the device, and it is the one handling application data: applications are executed inside the CPU. Inside a computer, the NIC communicates with Central Processing Unit (CPU) of your PC thanks to the PCI Express bus, a channel of communication inside every computer that allows internal components to talk with each other. Intermediary network devices have several dozens of NICs because their role is to connect other devices together. A NIC manages only one type of connection, so you are going to have a NIC for ethernet connection and a NIC for wireless connections.

Each time the data traverses a layer from top to bottom, that layer adds some pieces of information. As we know, the information is originated by an application at the OSI layer 7, then it is passed down until it reaches the physical layer. This does not just allow the network layer to be truly and completely independent from the physical layer, but it allows the CPU and the application on it to imagine that they are talking directly to the application on the other device.This is where the concept of encapsulation becomes extremely important.

Information In A Layer 2 Frame Is Intended For Which Osi Layer? Plus All The

Instead, the NIC receives it and add to the Layer 3 PDU the information specific for the data link layer. In the CPU, we will prepare the data to be sent down to the network layer, then the CPU thinks that it has just sent the information this way. The application data, plus all the extra information added by layers, are called Protocol Data Unit (PDU), and the PDU of the presentation layer will be smaller than the PDU of the data link layer since at the data link layer more layers have added their information.In order to make two applications things that they are talking directly, like if they were on the same computer, we heavily leverage encapsulation. However, pieces of information are never added in the middle of the data. Encapsulation happens by adding some information at the beginning of data and, sometimes, at the end too. On the receiving device, these extra pieces of information are read from the intended layer and then removed before passing that data to the upper layer, so that in the end the receiving application will read just what the originating application sent.

This is at the very basis of any communication, without that communication wouldnвЂ™t be possible at all. Addressing at Layer 2The most important thing done at OSI layer 2 is the delivery of information to the destination device. In the following section, we will start to see what these pieces of information are and how they are used. In that, the LLC talks to the CPU and the MAC talks to the physical layer.The pieces of information added at the data link layer enable all the features of this layer like delivery of information to the correct receiver over a shared media or interference detection. The network layer PDU is called Packet, while the data-link layer PDU is called Frame, so the NIC will have to put packets into frames when sending and extrapolate packets from frames when receiving.Devices think that they are communicating directly at Layer 3, but in reality the L3 data is encapsulated into L2 envelopes at the NIC-level of the sender and de-encapsulated at the NIC-level of the receiver: the real path is the dashed one. If so, it will remove the data link layer information and pass the rest to the CPU, so that the receiving CPU will think it just received network data.

A MAC address is long six bytes and it is represented in hexadecimal notation. Like snail mail delivery, we read the address on the envelope to know where the letter has to go.Like houses in a road have addresses, PCs in a network have MAC addresses.These strange codes you see in the picture are the Layer 2 addresses of the devices: the MAC addresses. And this is a lot like snail mail letters, the data link layer information is an envelope containing data from upper layers.

To represent 16 values in binary, we would need 4 bits, so a single hexadecimal digit will represent a nibble and two will represent a byte. You donвЂ™t need to know hexadecimal math as binary math, but it is handy to know the basics.Each digit is worth 16 values, going from 0 to 9 and then from A to F. Hexadecimal notation is just like that: decimal notation is based on powers of ten, binary notation is based on powers of two and hexadecimal notation is based on powers of 16.

Large NIC producers such as Cisco have purchased several OUIs because they produce so many NICs that having just three bytes to define their unique identifier was not enough. Then, when that company will produce NICs, it will assign the last three bytes of the MAC to the NIC.

Mac Information In A Layer 2 Frame Is Intended For Which Osi Layer?