Research On Transport Technologies And Resources Opimal Management Algorithms For Carrier Ethernet

Carrier Ethernet is an international and inland hotspot, and a great deal of human and material resource is plunged into research on carrier Ethernet.Aiming at the shortage of software system task scheduling in carrier Ethernet products, a novel task scheduling algorithm based on value-density, deadline and resource is presented in this paper. In the method, tasks are assigned priority levels based on compound of value-density, deadline and resource. The system schedules tasks by preemptive priority policy. The evaluation and test result shows: Under circumstance of system overload, average system value the method can get is 300% as that of EDF algorithm, 177% as that of the value based method, 162% as that of value-density based method.Aiming at the problem the hardware resources such as forwarding information tables in a carrier Ethernet product can't usually meet the changing application requests, a virtual hardware method used to improve forwarding performance of the carrier Ethernet system is brought forward in this paper. Test result shows: Under circumstance of CPU utility improving a little, the method can make the layer II destination lookup failure rate decline 50%, the layer III destination lookup failure rate decline 40% and the match rate of access control list increase 20%.Aiming at the dificiencies of current adaptive clock recovery methods for carrier Ethernet network, two adaptive clock methods are put forward in this paper. One method is local time scale and Karlman filter based method, and its main features is: the local clock and a high-frequency counter is used to get the timescale information of the sending end and receiving end and Karman filter is used to cancel the noise. Another method is jitter buffer based fast convergence method that uses variation of jitter buffer fill level to get the description of the clock difference between the two end clocks, and the double EWMA (Exponential Weight Moving Average) filter is used to carry out noise cancellation. The test results show: Under circumstance of CPU utility and programmable logic component improving a little, lock time of the former method is 33% lower than that of ordinary timestamp based method and 45% lower than that of ordinary buffer based method; lock time of the latter method is 40% lower than that of ordinary buffer based method.Aiming at the problems that current physical channel can cause information transport errors and network congestion can bring about data loss, an adaptive forward erroe correction method used to correct data errors caused by physical channel (data packet based forward error correction method) and an adaptive forward method used to recover lost packets (data packet group based forward error correction method) are advanced in this paper. The data packet based method is used to fix the physical channel error and the data packet group based method is mainly adopted in the scene that TDM is carried on carrier Ethernet network and it handles the influence of network congestion. The test results show: Under circumstance of communication bandwidth improving a little, the former method can make the packet error ratio drop to 3% of the original packet error ratio; the latter method can make packet lost ratio drop to 1.0×10^-4 of the original packet loss ration.Aiming at the problem that network congestion influence the transport quality when real-time services such as voice and video are carried on carrier Ethernet network, an adaptive jitter buffer management method is presented in this paper. The method used simplied E-Model to evaluate the performance of the jitter buffer and search the optimum jitter buffer size under current network status. the Test result shows: Under circumstance of CPU utility and programmable logic component improving a little, the method can make the transport grade parameter R which is used to evaluate the quality of service in E-Model improved. The value of R can increase 5 and the grade of R can increase 1.The above researches are realized, test and evaluated on the carrier class Ethernet service platforms that have 12.8Gbps, 256Gbps and 800Gbps switch capacity respectively. Carrier Ethernet devices based on the platforms are widely applied in actual networks.