| Summary: | 碩士 === 國立中興大學 === 資訊科學研究所 === 92 === In this thesis, we focus on system disruption caused by wild scale power outage or serious failure under DOCSIS （Data Over Cable Service Interface Specification）protocol over CATV （Community Antenna Television Networks） networks. There are a large number of Cable Modems (CMs) which are made to communicate with Cable Modem Termination System (CMTS) for acquiring parameters from CMTS to work again after the failure drove out; hence, CMs need to go through the ranging process. The major goal of the ranging process is to enable CMs to acquire the value of time offset from itself to CMTS, similar to synchronization process.
Before system disruption, an active CM must get some information from flash memory during recovery, such as accurate power level, service flow priority value, etc. One CM may has several services in process; therefore we assign different values to different services according to the priority mechanism of the QoS provided by DOCSIS 2.0. A CM should record the highest service value in process to flash memory. In the same way, CMTS also needs to configure one counter to each priority for recording the number of CMs in this priority. Thus, we can divide the initial maintenance region of MAP into several areas during system recovery. A CM with a different priority value only accesses related area of which its priority value is either equal to or less than that of the CM. It then will enable the CMs with higher priorities to complete the ranging process earlier than those with lower priorities, and therefore, accomplishes the process of registration and then goes on to transmit data. In this thesis, we also compare the effects of using different parameters, in order to reduce recovery time.
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