计算机网络2（Computer network 2）.doc

计算机网络2（Computer network 2） What are the performance metrics of a computer network? 1.? Whats the rate?? Concept: the speed of a network means how much data a network can transmit over a unit time. It can also be called data rate (data rate) or bit rate (bit, rate). It is an important performance index in the computer network, units: b/s, or kb/s, Mb/s, Gb/s, etc.??? Note: speed is often referred to as the constant speed or the nominal speed. ???? 2.. Bandwidth: the origin of bandwidth (bandwidth): bandwidth originally refers to the bandwidth of the signal that is used to represent the content of the data. The unit of signal bandwidth is the Hertz (or kHz, MHz, GHz, etc.). The concept of live (Network) bandwidth refers to the highest data rate of data that can be transmitted over a digital channel. What is the current bandwidth per unit, bit per second, or b/s, or bit/s??? 3. throughput. Concept throughput (throughput) is the amount of data that passes through a network (or channel, interface) within a unit time. Throughput is usually used to measure a real network in order to know exactly how much data is actually transmitted through the network. Note that throughput is subject to the bandwidth of the network or the networks rated speed. ???? 4., delay (delay, or latency), the concept of delay, refers to the length of time required for data to be received from the start to the full reception. The delay in network transmission can usually be decomposed into several different parts: propagation delay, propagation delay, processing delay, queuing delay, delay (delay, or latency)?? (1) the transmission delay (delay)? Refers to transmit data, time data blocks from the node into the transmission media need is transmitted from a data block (frame) of the first bit count to the data block (frame) the last bit is sent the required time. ????? (2) propagation delay refers to the time spent by electromagnetic waves in the channel when they need to propagate a certain distance.