实务-4（Practice -4）.docVIP

实务-4（Practice -4） I. Communication Network Overview 1, there are several elements of a network protocol. What aspects of each element are involved? 1) syntax: the format, encoding, and signal level of data and control information 2) semantics: involves control information for coordination and error handling 3) synchronization: speed matching and sorting Two, fixed telephone network 1, at this stage, the structure of our long-distance network is (two level) structure 2, traffic on a low loss direct route is allowed to overflow to other routes. (x) 3, traffic on efficient direct routes is allowed to overflow to other routes. (V) 4, the data information is transmitted by the circuit switched network, and the encoding method and the format of the data signals are not limited. (V) 5. Briefly describe the basic functions of switching nodes. 1) correctly receive and analyze call signals from subscriber and trunk lines 2) correctly receive and analyze address signals sent from subscriber and trunk lines 3) to correctly route the destination address and forward the signal on the relay line 4) able to control connection creation 5) the connection can be removed in accordance with the release signal received Three packet switching network 1, a brief analysis of datagram and virtual circuit Answer: the data reported: by every user data message packet split independently, each node according to the destination address of the packet switches for each packet routing, packet with a message can be respectively along different paths through the network to the same destination. In the network, the terminal needs to be reordered by grouping numbers, and then the packet header is recombined to restore the full message. Virtual circuit mode: initiates the call before the two parties transmit data. The network establishes a logical circuit for the call. Then, the user sends the packet on the logical circuit and the communication circuit is finished. Four, digital data network What are the