分组交换网是适应计算机和通信要求而发展起来的一种先进的数据传输系统 ,具有点多线长的特点 ,主要包含有主机、调制解调器 (Modem)、不间断电源 (UPS) ,以及光纤、载波、引入电缆等各类传输通道。由于系统设备繁杂 ,各环节紧密联系 ,因此一旦出现故障延时 ,将影响其高效运作 Packet-switched network is an advanced data transmission system developed to meet the requirements of computer and communication. It has the characteristics of multi-line length, including host, modem, uninterruptible power supply (UPS), optical fiber, , The introduction of cable and other types of transmission channels. Due to the complex system equipment, all aspects of close contact, so once the failure delay, it will affect the efficient operation