Wang-Cheol Song

OF@TEIN: An OpenFlow-enabled SDN Testbed over International SmartX Rack Sites

In this paper, we will discuss our on-going effort for OF@TEIN SDN (Software-Defined Networking) testbed, which currently spans over Korea and five South-East Asian (SEA) collaborators with internationally deployed OpenFlowenabled SmartX Racks.

Traffic aware optimized zone based hierarchal link state routing protocol for VANET

VANET plays an important role in dissemination of traffic and emergency information among vehicles moving on roads. This information is used by various vehicular applications like safety applications, route guiding applications etc. However, because of high mobility of vehicular nodes, maintenance of routing tables generates high network traffic. In this paper we have proposed an optimization of Zone based Hierarchical Link State (ZHLS) routing protocol for VANET. The two tier topology of ZHLS allows building of a relatively stable routing path, however because of its proactive nature ZHLS creates huge network overhead when nodes are increased. In order to overcome this issue of network overhead that every proactive protocol causes we have optimized routing parameters of ZHLS based on traffic awareness and network performance. The proposed traffic aware optimized framework allows each vehicle to update its time interval for dissemination of routing information based on its context. Our experiments have proved our claim that by optimizing routing parameters of ZHLS a better performance in term of packet delivery ratio with low network overhead can be achieved.

Data aggregation for Vehicular Ad-hoc Network using particle swarm optimization

The data aggregation process can be considered a problem of multi-objective optimization which reduces the size of data in such a way that its relevance with original data remains as closer as possible. Data Aggregation is of great importance in Wireless Sensor Networks, Vehicular Ad-hoc Networks to transmit the recorded data in time over low bandwidth. In this regard, data aggregation solutions have been developed; however, their actual usage has been limited, for the reason of low accuracy and high processing time. In this paper, particle swarm optimization (PSO) is used to optimize process of multi-objective data aggregation in vehicular ad-hoc network. In our work processing time for aggregation and aggregation quality have been set as objectives. The proposed method has been compared with state of the art existing aggregation techniques. Experimental results show that our method simplifies aggregation effectively and obtains a higher aggregation accuracy compared to the other data aggregation methods.

Geocasting in Wireless Ad Hoc Networks with Guaranteed Delivery

In this paper, we address the problem of delivering the geocast packets to all nodes inside the geocast region in an ad hoc network, which are not directly connected to one another. We propose a geocast routing protocol that guarantees the delivery of geocast packets to all nodes inside a geocast region. In order to guarantee the delivery of packets to all nodes, we make use of the nodes outside the geocast region. We call the isolated group of nodes inside the geocast region as islands. There can be several nodes outside the geocast region that have direct connections with the islands, but we elect one node called Main Entry Point (MEP) which is responsible for delivering the packets to the nodes inside the geocast region. Our mechanism is quite efficient and guarantees the delivery of geocast packets to all nodes inside the geocast region.

Visualization of elephant flows and QoS provisioning in SDN-based networks

Elephant flows in data center networks have a tendency to utilize a lot of bandwidth, leaving latency-sensitive mice flows choked behind them. This causes degradation of application performance running on the network. Therefore, a data center network should be able to not only identify elephant flows, but also offer Quality of Service (QoS) provisioning. SDN makes network operating systems to achieve greater governance of the control plane within a given network. In order to detect elephant flows, we use a framework based on sFlow sampling technology. We show an approach to guarantee QoS that is administered and defined by a centralized network controller by using SDN and specifications offered by OpenFlow. Although there have been efforts in this area over the past but in the scope of this paper, we will only focus on how Traffic Shaping (rate limiting) based classification technique can be used within an SDN network.

Cluster based data aggregation in vehicular adhoc network

Information aggregation is used to fuse interrelated data items collected from different nodes before redistributing them. Thus, using aggregation the number of transmissions and the communication overhead can be reduced significantly. Particularly for applications which require periodic dissemination of information into a large region, aggregation becomes prerequisite. Let us consider an example of self-organized infrastructure less traffic information system where each vehicle periodically disseminates its speed, position and information about road conditions. The aim is to design such data aggregation technique that not only use low bandwidth for data dissemination after aggregation process but also use low bandwidth for data collection from source nodes as well. As VANET environment has limited bandwidth this data aggregation becomes the need of hour for efficient data processing and dissemination without network overhead. In this work we have proposed a cluster based data aggregation technique where vehicles are divided into autonomous clusters headed by cluster-head. Data is send to cluster-head that perform the aggregation of data and dissimulate it into network.

Managing Clouds, Smart Networks and Services: A Report on APNOMS 2011

This article presents a report on APNOMS 2011, which was held September 21–23, 2011 in Taipei, Taiwan. The theme of APNOMS 2011 was “Managing Clouds, Smart Networks and Services.”

Two-Level Hierarchical Routing Based on Road Connectivity in VANETs

Vehicular ad hoc networks have received considerable attention in recent years. Being a subclass of mobile ad hoc networks, VANETs have some different characteristics than MANETs such as, fast moving nodes and frequent disconnections in the network. Existing routing protocols of MANETs do not perform well under these dynamic conditions in VANETs. We present a two-level hierarchical routing protocol based on road connectivity in VANETs called Hybrid Road-Aware Routing (HRAR) designed specifically for inter- vehicle communication in urban and/or highway environments. A distinguished property of HRAR is its ability to not only discover the available paths between source and destination pairs but also to re-adjust the paths on the fly, without starting a new destination discovery process. Unlike other routing protocols, the path from source to destination is made by road ids. Gateway nodes help in locating the destination and forwarding the packets from one road segment to other. For the evaluation of HRAR protocol, we perform extensive simulations and results show that HRAR can help in design and deployment of VANETs.

Road aware QoS routing in VANETs

Vehicular Ad Hoc Network (VANET) is a subclass of Mobile Ad Hoc Network (MANET). QoS routing protocols are fundamental part of VANETs that aim to provide services with guaranteed quality. Existing routing protocols of MANET can be applied to VANETs as well but they do not perform well under the dynamic conditions of VANETs such as, fast moving nodes and frequent disconnections in the network. In this paper we propose a novel QoS routing protocol for VANETs. The proposed scheme takes a localization approach by a road segment as a road between intersections. Every road segment can calculate candidate paths with QoS parameters, and vehicles on intersections serve as the gateway nodes to calculate the weights for the routes on local road segments and select reliable route based on these weights to connect the road segments. Our proposed scheme is designed to improve the delivery ratio and end to end delay with guaranteed quality in highly mobile VANET environments. The simulation results show that our proposed scheme performs better than AODV in aforementioned performance metrics.

Delivery-Guaranteed Geocast in MANETs by Using ZHLS

The challenging problem in geocasting is distributing the packets to all the nodes within the geocast region with high probability. Sending packets to a node in the geocast region cannot guarantee delivery to all nodes in the region. It is because there may be some islands in which nodes are not connected each other within the region while they may reach through outside the region. Some geocast algorithms have been proposed to guarantee delivery in the wireless ad hoc networks, but they don’t consider mobile nodes. This paper suggests using ZHLS for Geocasting for guaranteed delivery in mobile ad hoc networks. As ZHLS exchanges topology information between nodes unlike other location-aware routing algorithm, dead end in the searching path could be avoided, and as the zone level topology in ZHLS is relatively stable in MANETs, influence of mobility could be minimized. We expect that delivery to all of nodes in the geocast region could be guaranteed by adding simple search algorithm to ZHLS in MANET environment.