Which Pdu Format Is Used When Bits Are Received From The Network Medium By The Nic Of A Host?

Which PDU Format Is Used When Bits Are Received From The Network Medium By The Nic Of A Host?

It uses the frame PDU format when the bits are received from the network medium by the nic of the host.

Now, let us learn about the PDU. PDU stands as a protocol data unit. We know that the OSI model consists of different layers. At each layer, the data is transferred in different formats.

We have different data formats like frames, segments, bits, and packets. In the above three layers of the OSI model i.e application layer, presentation layer, session layer, the data format is called the PDU’s. We do not have any separate names for the above layers, we simply call them the protocol data units.

But the bottom four layers, i.e physical layer, data link layer, network layer, transport layer. Each has the specific names for the data formats at the different layers. The frame is the PDU at layer 2 of the OSI model. Layer 2 of the OSI model is called the data link layer. And the devices that deal with this are called the layer 2 switches.

It makes some of the forwarding decisions based on the layer 2 addresses. The frame would be the information present at the layer 2 header and includes the source and the destination inside the header. Another Protocol data unit is the segments, the segments are the data format at the transport layer.

The data is divided into smaller segments. This can be called segmenting. So segments are the protocol data unit at the transport layer. Another type of data format is called bits. These bits can be zeroes or ones that are sent across the network. The bits fit at the physical layer of the OSI model. And the last type of data format is the packets. The packets are the protocol data format at the network layer of the OSI model.

The sender’s data travels from the different layers of the OSI model. Each layer of the OSI model will encapsulate the data by adding the header. This process is called data encapsulation. The user starts transferring the data at the application layer. And the data moves down to the presentation layer that is compressed in a standard data format, sometimes the data will be in an encrypted format. And the data moves to the session layer.

A session ID is get attached to the data. At this session layer, the data will be in one whole block. After this, then data is moved to the transport layer. As we discussed earlier, the data that is traveling at each layer will call with different PDU names.

Now, when the data comes to the transport layer, the data will be divided into different pieces. Each block will be with the header attached to it that contains the destination port, source port, sequence number, and some of the other information connected to it. These divided blocks we call the segments. And these segments travel to the network layer. This network layer again adds another IP header, it adds a new IP packet.

This contains source and destination Ip address with some of the other information. And the IP packets move from the network layer to the data link layer. Same as earlier new header gets added and a new PDU is built called frames.
This iframe contains the source mac address and the destination mac address and some other control information. It is also used for error checking. At last, the frame is sent into the physical layer where the data is translated in the form of signals. These PDU’s are in the format of the bit.