In recent years,dual-homed topologies have appeared in data centers in order to offer higher aggregate bandwidth by using multiple paths simultaneously.Multipath TCP(MPTCP) has been proposed as a replacement for TCP i...In recent years,dual-homed topologies have appeared in data centers in order to offer higher aggregate bandwidth by using multiple paths simultaneously.Multipath TCP(MPTCP) has been proposed as a replacement for TCP in those topologies as it can efficiently offer improved throughput and better fairness.However,we have found that MPTCP has a problem in terms of incast collapse where the receiver suffers a drastic goodput drop when it simultaneously requests data over multiple servers.In this paper,we investigate why the goodput collapses even if MPTCP is able to actively relieve hot spots.In order to address the problem,we propose an equally-weighted congestion control algorithm for MPTCP,namely EW-MPTCP,without need for centralized control,additional infrastructure and a hardware upgrade.In our scheme,in addition to the coupled congestion control performed on each subflow of an MPTCP connection,we allow each subflow to perform an additional congestion control operation by weighting the congestion window in reverse proportion to the number of servers.The goal is to mitigate incast collapse by allowing multiple MPTCP subflows to compete fairly with a single-TCP flow at the shared bottleneck.The simulation results show that our solution mitigates the incast problem and noticeably improves goodput in data centers.展开更多
For the purpose of enhancing automobile safety and the effectiveness of recalls,increasing manufacturers' quality control capabilities,and reducing defects,we investigated thestatus of recalls over the last five y...For the purpose of enhancing automobile safety and the effectiveness of recalls,increasing manufacturers' quality control capabilities,and reducing defects,we investigated thestatus of recalls over the last five years.We have examined patterns and trends in motor vehiclesafety recalls using databases from China,Europe and the United States.A recall rate parameterwas developed to evaluate the level of recall enforcement based on analyzing the reasonsfor recalls and manufactures' characteristics.Moreover,there were substantial differencesin the recall rates of China compared with those in other countries,indicating that Chinese manufacturersneed to take more active action in recall.展开更多
基金supported in part by the HUT Distributed and Mobile Cloud Systems research project and Tekes within the ITEA2 project 10014 EASI-CLOUDS
文摘In recent years,dual-homed topologies have appeared in data centers in order to offer higher aggregate bandwidth by using multiple paths simultaneously.Multipath TCP(MPTCP) has been proposed as a replacement for TCP in those topologies as it can efficiently offer improved throughput and better fairness.However,we have found that MPTCP has a problem in terms of incast collapse where the receiver suffers a drastic goodput drop when it simultaneously requests data over multiple servers.In this paper,we investigate why the goodput collapses even if MPTCP is able to actively relieve hot spots.In order to address the problem,we propose an equally-weighted congestion control algorithm for MPTCP,namely EW-MPTCP,without need for centralized control,additional infrastructure and a hardware upgrade.In our scheme,in addition to the coupled congestion control performed on each subflow of an MPTCP connection,we allow each subflow to perform an additional congestion control operation by weighting the congestion window in reverse proportion to the number of servers.The goal is to mitigate incast collapse by allowing multiple MPTCP subflows to compete fairly with a single-TCP flow at the shared bottleneck.The simulation results show that our solution mitigates the incast problem and noticeably improves goodput in data centers.
文摘For the purpose of enhancing automobile safety and the effectiveness of recalls,increasing manufacturers' quality control capabilities,and reducing defects,we investigated thestatus of recalls over the last five years.We have examined patterns and trends in motor vehiclesafety recalls using databases from China,Europe and the United States.A recall rate parameterwas developed to evaluate the level of recall enforcement based on analyzing the reasonsfor recalls and manufactures' characteristics.Moreover,there were substantial differencesin the recall rates of China compared with those in other countries,indicating that Chinese manufacturersneed to take more active action in recall.
