Traffic simulators are utilized to solve a variety of traffic-related problems.For such simulators,origin-destination(OD)traffic volumes as mobility demands are required to input,and we need to estimate them.The autho...Traffic simulators are utilized to solve a variety of traffic-related problems.For such simulators,origin-destination(OD)traffic volumes as mobility demands are required to input,and we need to estimate them.The authors regard an OD estimation as a bi-level programming problem,and apply a microscopic traffic simulation model to it.However,the simulation trials can be computationally expensive if full dynamic rerouting is allowed,when employing multi-agent-based models in the estimation process.This paper proposes an efficient OD estimation method using a multi-agent-based simulator with restricted dynamic rerouting to reduce the computational load.Even though,in the case of large traffic demand,the restriction on dynamic rerouting can result in heavier congestion.The authors resolve this problem by introducing constraints of the bi-level programming problem depending on link congestion.Test results show that the accuracy of the link traffic volume reproduced with the proposed method is virtually identical to that of existing methods but that the proposed method is more computationally efficient in a wide-range or high-demand context.展开更多
It is well-known that today's inter-domain routing protocol, Border Gateway Protocol (BGP), converges slowly during network failures. During the convergence period, widespread tempo-rary burst packet loss happens ...It is well-known that today's inter-domain routing protocol, Border Gateway Protocol (BGP), converges slowly during network failures. During the convergence period, widespread tempo-rary burst packet loss happens that may be caused by route loops or blackholes. In this paper, we present a Protection Tunnel based Rerouting (PTR) mechanism-a novel scheme for delivering packet continuously during period of convergence. PTR scheme pre-establishes protection tunnel among routers. Once the inter-domain link failed, routers could redirect those influenced packets along pro-tection tunnel to a router that has a valid path to destination. Therefore, packets could be forwarded continuously even encountering fault links. The performances of PTR scheme are simulated. The results demonstrate that PTR scheme is more resilient to link failures than BGP. The cost caused by PTR scheme is very little and acceptable.展开更多
As the technology of IP Fast Rerouting (FRR) become mature and the related methods and specifi cation such as RFC5286 accepted as standard, it is expected that IP FRR will be deployed gradually and will enhance the su...As the technology of IP Fast Rerouting (FRR) become mature and the related methods and specifi cation such as RFC5286 accepted as standard, it is expected that IP FRR will be deployed gradually and will enhance the survivability of IP network. This paper presents a different method for computing the Loop-free Alternate Interfaces. The new algorithm can be referred as "Next-Hop Cost Decrease (NHCD)" criterion. Compared with the RFC5286 LFA method, NHCD can handle both the simultaneous link failure and node failure, including multi-link failures. It has less computational complexity and can be used uniformly in the Traffi c Engineering and Network Recovery. However, NHCD is somewhat lower than the LFA method on recovery ratio of single link failure. After a formal description of NHCD criterion and a proof of loopfree alternates, the paper presents the simulation results of NHCD.展开更多
基金supported by JSPS KAKENHI (Grant Nos.15H01785 and 19H02377).
文摘Traffic simulators are utilized to solve a variety of traffic-related problems.For such simulators,origin-destination(OD)traffic volumes as mobility demands are required to input,and we need to estimate them.The authors regard an OD estimation as a bi-level programming problem,and apply a microscopic traffic simulation model to it.However,the simulation trials can be computationally expensive if full dynamic rerouting is allowed,when employing multi-agent-based models in the estimation process.This paper proposes an efficient OD estimation method using a multi-agent-based simulator with restricted dynamic rerouting to reduce the computational load.Even though,in the case of large traffic demand,the restriction on dynamic rerouting can result in heavier congestion.The authors resolve this problem by introducing constraints of the bi-level programming problem depending on link congestion.Test results show that the accuracy of the link traffic volume reproduced with the proposed method is virtually identical to that of existing methods but that the proposed method is more computationally efficient in a wide-range or high-demand context.
基金Supported by the Major State Basic Research Development Program(No.2007CB307102)the State High Technology Research Development Program(No.2009AA01A346)
文摘It is well-known that today's inter-domain routing protocol, Border Gateway Protocol (BGP), converges slowly during network failures. During the convergence period, widespread tempo-rary burst packet loss happens that may be caused by route loops or blackholes. In this paper, we present a Protection Tunnel based Rerouting (PTR) mechanism-a novel scheme for delivering packet continuously during period of convergence. PTR scheme pre-establishes protection tunnel among routers. Once the inter-domain link failed, routers could redirect those influenced packets along pro-tection tunnel to a router that has a valid path to destination. Therefore, packets could be forwarded continuously even encountering fault links. The performances of PTR scheme are simulated. The results demonstrate that PTR scheme is more resilient to link failures than BGP. The cost caused by PTR scheme is very little and acceptable.
文摘As the technology of IP Fast Rerouting (FRR) become mature and the related methods and specifi cation such as RFC5286 accepted as standard, it is expected that IP FRR will be deployed gradually and will enhance the survivability of IP network. This paper presents a different method for computing the Loop-free Alternate Interfaces. The new algorithm can be referred as "Next-Hop Cost Decrease (NHCD)" criterion. Compared with the RFC5286 LFA method, NHCD can handle both the simultaneous link failure and node failure, including multi-link failures. It has less computational complexity and can be used uniformly in the Traffi c Engineering and Network Recovery. However, NHCD is somewhat lower than the LFA method on recovery ratio of single link failure. After a formal description of NHCD criterion and a proof of loopfree alternates, the paper presents the simulation results of NHCD.
