The intrinsic routing policy of NS2—a network simulation tool— based on flat or hierarchical address has the disadvantage such as small topology scale,high resource consumption,low efficiency and so on.This paper pr...The intrinsic routing policy of NS2—a network simulation tool— based on flat or hierarchical address has the disadvantage such as small topology scale,high resource consumption,low efficiency and so on.This paper proposes an IP based hierarchical routing strategy in network simulation to extend the topology scale and improve performance in simulating.Firstly,a stratification mechanism to identify IP address of nodes is described.Then,an algorithm of packet transmitting method(PTM) is presented for packet forwarding in the same subnet.Finally,algorithms of region partition(RP),routing computation based on region division(RCBRD) and routing distribution(RD) is proposed to implement regional segmentation,route calculation and route distribution for forwarding packets in different subnets respectively.The experiment results show that under the same condition,compared with plane address,the topology scale of the network simulation is extended two times and the consumption of time and memory during simulation is reduced by approximately 73%and 45.8% respectively.Compared with hierarchical address,the topology scale of the network simulation is expanded by more than 50%,and the consumption of time and memory is reduced by about 59.2% and 25% respectively.In addition,along with the growth of the node size,the proportion of reducing total simulation time and memory consumption would gradually increase.展开更多
An optimal design problem of local buffer allocation in the FMS is discussed in order to maximize a reward earned from processed jobs at all workstations. Structural properties of the optimal design problem are analyz...An optimal design problem of local buffer allocation in the FMS is discussed in order to maximize a reward earned from processed jobs at all workstations. Structural properties of the optimal design problem are analyzed for the model with two job routing policies. Based on these properties, approaches to optimal solutions are given.展开更多
Network failures are common on the Internet, and with mission-critical services widely applied, there grows demand for the Internet to maintain the performance in possibilities of failures. However, the border gateway...Network failures are common on the Internet, and with mission-critical services widely applied, there grows demand for the Internet to maintain the performance in possibilities of failures. However, the border gateway protocol（BGP） can not react quickly to be recovered from them, which leads to unreliable packet delivery degrading the end-to-end performance. Although much solutions were proposed to address the problem, there exist limitations. The authors designed a software defined autonomous system（AS）-level fast rerouting（SD-FRR） to efficiently recover from interdomain link failures in the administrative domain. The approach leverages the principle of software defined networking（SDN） to achieve the centralized control of the entire network. By considering routing policies and BGP decision rules, an algorithm that can automatically find a policy-compliant protection path in case of link failure was proposed. The OpenF low forwarding rules are installed on routers to ensure data forwarding. Furthermore, to deactivate the protection path, how to remove flow entries based on prefixes was proposed. Experiments show that the proposal provides effective failure recovery and does not introduce significant control overhead to the network.展开更多
基金Supported by the National Science and Technology Support Project(No.2012BAH45B01)the National Natural Science Foundation of China(No.61100189,61370215,61370211,61402137)the National Information Security 242 Project of China(No.2016A104)
文摘The intrinsic routing policy of NS2—a network simulation tool— based on flat or hierarchical address has the disadvantage such as small topology scale,high resource consumption,low efficiency and so on.This paper proposes an IP based hierarchical routing strategy in network simulation to extend the topology scale and improve performance in simulating.Firstly,a stratification mechanism to identify IP address of nodes is described.Then,an algorithm of packet transmitting method(PTM) is presented for packet forwarding in the same subnet.Finally,algorithms of region partition(RP),routing computation based on region division(RCBRD) and routing distribution(RD) is proposed to implement regional segmentation,route calculation and route distribution for forwarding packets in different subnets respectively.The experiment results show that under the same condition,compared with plane address,the topology scale of the network simulation is extended two times and the consumption of time and memory during simulation is reduced by approximately 73%and 45.8% respectively.Compared with hierarchical address,the topology scale of the network simulation is expanded by more than 50%,and the consumption of time and memory is reduced by about 59.2% and 25% respectively.In addition,along with the growth of the node size,the proportion of reducing total simulation time and memory consumption would gradually increase.
文摘An optimal design problem of local buffer allocation in the FMS is discussed in order to maximize a reward earned from processed jobs at all workstations. Structural properties of the optimal design problem are analyzed for the model with two job routing policies. Based on these properties, approaches to optimal solutions are given.
基金supported by the Open Fund of Robot Technology Used for Special Environment Key Laboratory of Sichuan Province of China (13zxtk03)
文摘Network failures are common on the Internet, and with mission-critical services widely applied, there grows demand for the Internet to maintain the performance in possibilities of failures. However, the border gateway protocol（BGP） can not react quickly to be recovered from them, which leads to unreliable packet delivery degrading the end-to-end performance. Although much solutions were proposed to address the problem, there exist limitations. The authors designed a software defined autonomous system（AS）-level fast rerouting（SD-FRR） to efficiently recover from interdomain link failures in the administrative domain. The approach leverages the principle of software defined networking（SDN） to achieve the centralized control of the entire network. By considering routing policies and BGP decision rules, an algorithm that can automatically find a policy-compliant protection path in case of link failure was proposed. The OpenF low forwarding rules are installed on routers to ensure data forwarding. Furthermore, to deactivate the protection path, how to remove flow entries based on prefixes was proposed. Experiments show that the proposal provides effective failure recovery and does not introduce significant control overhead to the network.
