Existing position-based routing algorithms, where packets are forwarded in the geographic direction of the destination, normally require that the forwarding node should know the positions of all neighbors in its trans...Existing position-based routing algorithms, where packets are forwarded in the geographic direction of the destination, normally require that the forwarding node should know the positions of all neighbors in its transmission range. This information on direct neighbors is gained by observing beacon messages that each node sends out periodically. Several beaconless greedy routing schemes have been proposed recently. However, none of the existing beaconless schemes guarantee the delivery of packets. Moreover, they incur communication overhead by sending excessive control messages or by broadcasting data packets. In this paper, we describe how existing localized position based routing schemes that guarantee delivery can be made beaconless, while preserving the same routes. In our guaranteed delivery beaconless routing scheme, the next hop is selected through the use of control RTS/CTS messages and biased timeouts. In greedy mode, the neighbor closest to destination responds first. In recovery mode, nodes closer to the source will select shorter timeouts, so that other neighbors, overhearing CTS packets, can eliminate their own CTS packets if they realize that their link to the source is not part of Gabriel graph. Nodes also cancel their packets after receiving data message sent by source to the selected neighbor. We analyze the behavior of our scheme on our simulation environment assuming ideal MAC, following GOAFR+ and GFG routing schemes. Our results demonstrate low communication overhead in addition to guaranteed delivery.展开更多
Network Coding is a relatively new forwarding paradigm where intermediate nodes perform a store, code, and forward operation on incoming packets. Traditional forwarding approaches, which employed a store and forward o...Network Coding is a relatively new forwarding paradigm where intermediate nodes perform a store, code, and forward operation on incoming packets. Traditional forwarding approaches, which employed a store and forward operation, have not been able to approach the limit of the max-flow min-cut throughput wherein sources transmitting information over bottleneck links have to compete for access to these links. With Network Coding, multiple sources are now able to transmit packets over bottleneck links simultaneously, achieving the max-flow min-cut through-put and increasing network capacity. While the majority of the contemporary literature has focused on the performance of Network Coding from a capacity perspective, the aim of this research has taken a new direction focusing on two Quality of Service metrics, e.g., Packet Delivery Ratio (PDR) and Latency, in conjunction with Network Coding protocols in Mobile Ad Hoc Networks (MANETs). Simulations are performed on static and mobile environments to determine a Quality of Service baseline comparison between Network Coding protocols and traditional ad hoc routing protocols. The results show that the Random Linear Network Coding protocol has the lowest Latency and Dynamic Source Routing protocol has the highest PDR in the static scenarios, and show that the Random Linear Network Coding protocol has the best cumulative performance for both PDR and Latency in the mobile scenarios.展开更多
Software-defined networking(SDN) has received tremendous attention from both industry and academia.The centralized control plane in SDN has a global view of the network and can be used to provide more effective soluti...Software-defined networking(SDN) has received tremendous attention from both industry and academia.The centralized control plane in SDN has a global view of the network and can be used to provide more effective solutions for complex problems,such as traffic engineering.This study is motivated by recent advancement in SDN and increasing popularity of multicasting applications.We propose a technique to increase the resiliency of multicasting in SDN based on the subtree protection mechanism.Multicasting is a group communication technology,which uses the network infrastructure efficiently by sending the data only once from one or multiple sources to a group of receivers that share a common path.Multicasting applications,e.g.,live video streaming and video conferencing,become popular,but they are delay-sensitive applications.Failures in an ongoing multicast session can cause packet losses and delay,which can significantly affect quality of service(Qo S).In this study,we adapt a subtree-based technique to protect a multicast tree constructed for Open Flow switches in SDN.The proposed algorithm can detect link or node failures from a multicast tree and then determines which part of the multicast tree requires changes in the flow table to recover from the failure.With a centralized controller in SDN,the backup paths can be created much more effectively in comparison to the signaling approach used in traditional multiprotocol label switching(MPLS) networks for backup paths,which makes the subtree-based protection mechanism feasible.We also implement a prototype of the algorithm in the POX controller and measure its performance by emulating failures in different tree topologies in Mininet.展开更多
基金Supported by Natural Sciences and Engineering Research Council, Collaborative Research and Development Grant (319848) of Canada
文摘Existing position-based routing algorithms, where packets are forwarded in the geographic direction of the destination, normally require that the forwarding node should know the positions of all neighbors in its transmission range. This information on direct neighbors is gained by observing beacon messages that each node sends out periodically. Several beaconless greedy routing schemes have been proposed recently. However, none of the existing beaconless schemes guarantee the delivery of packets. Moreover, they incur communication overhead by sending excessive control messages or by broadcasting data packets. In this paper, we describe how existing localized position based routing schemes that guarantee delivery can be made beaconless, while preserving the same routes. In our guaranteed delivery beaconless routing scheme, the next hop is selected through the use of control RTS/CTS messages and biased timeouts. In greedy mode, the neighbor closest to destination responds first. In recovery mode, nodes closer to the source will select shorter timeouts, so that other neighbors, overhearing CTS packets, can eliminate their own CTS packets if they realize that their link to the source is not part of Gabriel graph. Nodes also cancel their packets after receiving data message sent by source to the selected neighbor. We analyze the behavior of our scheme on our simulation environment assuming ideal MAC, following GOAFR+ and GFG routing schemes. Our results demonstrate low communication overhead in addition to guaranteed delivery.
文摘Network Coding is a relatively new forwarding paradigm where intermediate nodes perform a store, code, and forward operation on incoming packets. Traditional forwarding approaches, which employed a store and forward operation, have not been able to approach the limit of the max-flow min-cut throughput wherein sources transmitting information over bottleneck links have to compete for access to these links. With Network Coding, multiple sources are now able to transmit packets over bottleneck links simultaneously, achieving the max-flow min-cut through-put and increasing network capacity. While the majority of the contemporary literature has focused on the performance of Network Coding from a capacity perspective, the aim of this research has taken a new direction focusing on two Quality of Service metrics, e.g., Packet Delivery Ratio (PDR) and Latency, in conjunction with Network Coding protocols in Mobile Ad Hoc Networks (MANETs). Simulations are performed on static and mobile environments to determine a Quality of Service baseline comparison between Network Coding protocols and traditional ad hoc routing protocols. The results show that the Random Linear Network Coding protocol has the lowest Latency and Dynamic Source Routing protocol has the highest PDR in the static scenarios, and show that the Random Linear Network Coding protocol has the best cumulative performance for both PDR and Latency in the mobile scenarios.
文摘Software-defined networking(SDN) has received tremendous attention from both industry and academia.The centralized control plane in SDN has a global view of the network and can be used to provide more effective solutions for complex problems,such as traffic engineering.This study is motivated by recent advancement in SDN and increasing popularity of multicasting applications.We propose a technique to increase the resiliency of multicasting in SDN based on the subtree protection mechanism.Multicasting is a group communication technology,which uses the network infrastructure efficiently by sending the data only once from one or multiple sources to a group of receivers that share a common path.Multicasting applications,e.g.,live video streaming and video conferencing,become popular,but they are delay-sensitive applications.Failures in an ongoing multicast session can cause packet losses and delay,which can significantly affect quality of service(Qo S).In this study,we adapt a subtree-based technique to protect a multicast tree constructed for Open Flow switches in SDN.The proposed algorithm can detect link or node failures from a multicast tree and then determines which part of the multicast tree requires changes in the flow table to recover from the failure.With a centralized controller in SDN,the backup paths can be created much more effectively in comparison to the signaling approach used in traditional multiprotocol label switching(MPLS) networks for backup paths,which makes the subtree-based protection mechanism feasible.We also implement a prototype of the algorithm in the POX controller and measure its performance by emulating failures in different tree topologies in Mininet.
