Скачать с ютуб Frames and Packets - 5 в хорошем качестве

Frames and Packets - 5

As we mentioned, a frame or packet groups data so it can be sent across the network. For the remainder of this course we will refer to these groupings of data as packets, but remember, for our purposes today, frames and packets are the same thing. First, let's talk a bit about how data is sent across a network. Actually there are two ways data can be transmitted: streaming data and packetized data. Data streaming works like your telephone. First, you establish the connection, then send the data. This method works very well when only two devices are communicating, but not very well when many devices need to communicate. The second method is called packetized data. Packetized data, collecting data into packets, operates more like the mail system. Just like sending a letter, information is gathered into groups, like the pages in a letter, and then placed in a packet, or envelope. The packet is addressed to the destination and then sent across the network. When your computer needs to transmit data, the information is sent to the lower layers of the OSI model. Here your data is combined with protocol-specific information, and all the bytes of data are grouped to form a packet. Depending on the protocol, the size of the packet can be anywhere from a few bytes to tens of thousands of bytes. The variation in size is related to the protocol used and network limitations. Once the packet is formed, it is sent onto the network and it reaches a network switch. The switch examines the packet, determines its destination and adds it to a never-ending stream of data traffic. The packet may travel through many more intermediate switches before it reaches its destination. Each of these switches examines the packet, checks addressing information, then forwards it towards its destination. #frame #packet #FrameCheckSequence