ccna 200-301 network simulator tools plus prospect

ccna 200-301 network simulator tools plus prospect.2. UDP UDP (User DatagramProtocol) is a connectionless transport protocol in the TCP/IP stack,k34Shout Chapter 2 Network Interconnection and Reference Models*** | 02 Its data segmentation format is shown in Figure 2-4-7. UDP is a simple protocol that exchanges datagrams without acknowledgment mechanisms or transmission guarantees; error handling and retransmission mechanisms must be done by the upper layer protocols. The simplicity of UDP is evident from the data segmentation formats of TCP and UDP. The UDP protocol is mainly oriented towards request/response transactional applications, where a transaction often involves only two exchanges of messages, and the overhead of establishing and withdrawing a connection for this purpose is considerable, which makes the use of UDP very efficient. In addition, the UDP protocol is also used in applications where reliability is not critical, but where low network latency is required, such as the transmission of voice and video data.31bit ObitSource PortM Port (16) Destination PortDestination Port (16)Check Sum (16) Emergency (16)Data (variable)Sweat section headerFigure 2.4-7 UDP data segmentation format Multicast generally uses the UDP protocol, and many broadcast teaching software, such as "Extreme eClassroom" teaching software uses multicast address and UDP protocol, the teacher machine only needs to send one copy of data to the multicast address, and all students join this multicast address to receive the teacher machine's broadcast teaching. The number of student machines has little impact on the performance of the teacher machine. The Netmeeting program, also known as web conferencing, can also be used for broadcast teaching, and the teacher machine can share its own screen, but this software uses the TCP protocol, which is an end-to-end connection, and needs to confirm the retransmission mechanism, and the performance of the teacher machine is affected by the number of student machines, and the teacher machine can only directlyThe performance of the teacher machine is affected by the number of students, and the teacher machine can only connect to a dozen student machines directly.