ccna q&a

ccna q&a.Data segment Transport layerPacket Network layer (TCP/IP calls it a datagram)Frame Data link layerBit Physical layerExam Points Keep in mind the terms listed in Table 2.3. In addition, computers use binary to process data °Upon arrival at the physical layer, the bits of the data link layer frame are converted to levels, optical signals, radio waves, or other signals, depending on the type of physical medium used. The target device receives the message and performs the opposite process - unpacking the message: each layer strips the headers and tails as the message travels up the OSI reference model.Figure 2.5 illustrates the encapsulation and unencapsulation process as data is passed down and up the OSI reference model through an example. In this example, the application layer, representation layer, and session layer create the data. As the data is passed down layer by layer, headers (and possibly tails, as most Layer 2 protocols do) are added at each layerThe next few subsections will help you gain a deeper understanding of the process of transferring information between computers. The next subsection provides insight into the process of encapsulating the message, passing it down the protocol stack and onto the cable to the destination; the subsequent subsection describes the opposite process: unpacking the message at the destination and handing it off to the correct application at the application layer. The next subsection describes the more complex scenario: the case where the transfer of information from the source device to the destination device involves a bridge, a router, and a hub.2.3.1 Passing Down the Protocol StackThis section discusses the basic mechanisms of how information is processed as it is passed down the computer's protocol stack. Figure 2.5 illustrates the process of sending data from PC-A to PC-B. This example assumes that the data link layer is Ethernet and the physical layer is copper cable.