Yoshinori Kitatsuji

A distributed real-time tool for IP-flow measurement

It is getting more difficult to monitor multiple services as well as to detect and/or to trace denial of service attacks with only tools showing graphs of the whole IP layer traffic like MRTG or by checking counters of router interfaces. In this paper, we discuss the specification of a software-based real-time measurement tool for flow which consists of multiple capture devices, a manager device and user interface devices, enabling flexible flow definition on demand without stopping system and working with IPv4 and/or IPv6, while also enabling high performance. With this discussion, we propose its architecture, bit-pattern-based flow definition method and data structure. Then we report on the performance evaluation of a prototype of proposed real-time flow measurement tools developed on PC-UNIXs and show that the number of bit-pattern composing flow definitions impact on the performance. Lastly we show an example of measuring flows in a real world environment and confirm that the flow extraction is simplified.

Efficient ANDSF-assisted Wi-Fi control for mobile data offloading

This paper presents a strategic solution to mobile data offloading between 3GPP and non-3GPP access networks. As mobile data traffic is increasing rapidly, many 3G operators face massive challenges in managing the huge amount of mobile data traffic. Thus, mobile data offloading to non-3GPP access networks in 3G-access networks is necessary. In this paper, we propose a novel ANDSF-assisted Wi-Fi control method based on users high-level motion states, such as walking, driving, and recognizing whether the user is stationary or not, to avoid unnecessary Wi-Fi scanning and connections. The proposed method is compared to a client-based Wi-Fi connection manager, which performs periodic Wi-Fi scanning. According to the performance results, the proposed mechanism shows significant performance improvement in terms of efficient Wi-Fi control and connectivity with 3G and WiFi.

Bring your own network — Design and implementation of a virtualized WiFi network

This paper proposes virtualized WiFi network that can dynamically create a virtual Base Station (vBS) around the target mobile devices that offers dedicated base station resources for satisfying service-specific QoS and works as a gateway for a corresponding virtual network or slice. Specifically, the paper proposes (1) a technique to dynamically configure a vBS on top of multiple physical WiFi base stations by exploiting the features of OpenFlow, and (2) a technique of network-driven seamless handover between vBSs by forced association and authentication in advance at a target vBS. The paper also describes a detailed design and implementation of a physical WiFi base station which can organize a vBS, named virtualization capable WiFi Base Station (vcBS). As a prototype, two vcBSs and virtualization capable Base Stations Switch (vcBS-SW) to accommodate and centrally control those vcBSs are newly developed. The paper demonstrates a vBS can be dynamically configured on top of two vcBSs and the base station resource can be dynamically allocated to the vBS by assigning additional WiFi interfaces or frequency channels based on a resource allocation policy. The paper also demonstrates the proportion of SIP calls whose setup time exceed the threshold of 600ms can be reduced from 19.7% to 4.6%, when the SIP signaling traffic is served by a SIP-specific vBS. Finally the paper demonstrates that the prototype system can make seamless handover for a target device from common vBS to service-specific vBS in less than 65 ms without any packet drop.

Bring your own network — A network management technique to mitigate the impact of signaling traffic on network resource utilization

This paper proposes the concept of Bring Your Own Network (BYON), which could be a solution to reduce the impact of signaling traffic on the efficiency of mobile network resource utilization. The BYON would be enabled by dynamically migrating and localizing related service resources as well as configuring a service-specific wired and wireless network in a coordinated manner considering the distribution shape of the devices using the specific-service as well as their mobility tendency. The signaling traffic overhead is formulated, and how the introduction of the BYON could reduce the overhead is discussed. It is shown that a modified mobile network based on the BYON, in which the functions of P-CSCF and S/I-CSCF for IP Multimedia Subsystem (IMS) are migrated onto the location of PGW in Evolved Packet Core (EPC), could reduce the signaling traffic overhead by around 30 %. This paper also details the plan to deploy a large-scale experimental wireless network environment to demonstrate the concept of BYON, i.e., virtual wireless network facility.

A study on traffic management cooperating with IMS in MPLS networks

IMS (IP multimedia subsystem) is a key technology, to enable NSPs (network service providers) to provide various services over IP-based networks. In order for NSPs to provide stable network services, it is important to realize QoS in the transport stratum. RACF (Resource and admission control functions) has being standardized to perform admission control from the demands of users. However, the admission control of RACF for MPLS (Multiprotocol label switching) requires high functionality in the routers (e.g., monitor traffic and traffic shaping in each LSP [Label switched paths]) and gives large impact on the operation of NSPs. By utilizing the information which IMS function provides and basic MPLS function, we propose the feasible traffic management which distributes the traffic of specific class over multiple LSPs (Label switched paths) in the consideration of the traffic accommodation. Our evaluation shows that the proposed method distributing the traffic over two LSPs has enough effect.

Service-Specific Network Virtualization to Reduce Signaling Processing Loads in EPC/IMS

This paper proposes a service-specific network virtualization to address the tremendous increase in the signaling processing load in the evolved packet core and IP multimedia subsystem of a fifth-generation mobile communication system. The proposal creates several virtual networks that are composed of functions specialized for particular services on a mobile communication network and efficiently forwards a sequence of signaling messages to the appropriate virtual networks. Using a prototype system, this paper verifies the overheads costs of the proposal that are incurred during the inspection of packet application headers needed to appropriately forward signaling messages as well as the overheads incurred when replicating state information from one virtual network to another. This paper shows that the proposal can reduce the signaling processing load by ~25% under certain assumptions.

On flow distribution over multiple paths based on traffic characteristics

In traffic engineering to effectively distribute traffic flows over multiple network paths, taking into account traffic characteristics for individual flows is vital in appropriately assigning flows to network paths for achieving better delay performance of the total traffic All flows assigned to a path, in which some flows are highly bursty, equally experience a significant queuing delay when the path is highly utilized We analyze the mean, variance, and 99.5th percentile of queuing delay when two types of flows are multiplexed into a single path using an infinite buffer model with on-off state fluid flows This is carried out to find a better traffic distribution strategy over multiple paths so as to lower queuing delay incurred to multiplexed flows with distinct traffic characteristics From the analytical results, we found that trivial strategies, such as dividing individual types of flows in a proportional manner to the bandwidth of each path, or segregating distinct types of flows as much as possible, do not always achieve a good delay performance, e.g., in terms of max-min fairness Thus, the flows should be distributed considering their traffic characteristics, the number of flows, and the path bandwidths.

Traffic Characteristics-Based Flow Assignment Method for Reducing Queuing Delay

In traffic engineering, for effectively distributing traffic flows over multiple network paths, it is vital to take traffic characteristics of individual flows into account in appropriately assigning the flows to the network paths to achieve better delay performance as a whole. We have developed a traffic characteristic-based flow assignment method that reduces queuing delay in a buffer at the beginning of each network path. By taking the traffic characteristics of individual flows into account the method can effectively assigns flows to the paths so as to minimize overall queuing delay. We consider the simple case in which two types of flows with distinct traffic characteristics (buStiness) are assigned to two bandwidth-guaranteed paths. The flow assignment of our method reduces the queuing delay (at the edge router) of the worse path, by attempting to optimize the min-max fairness between the paths in terms of queuing delay. Numerical simulation showed that the method assigned the flows such that the queuing delay was reduced up to 40% compared with that when conventional path utilization based flow assignment was used. This means that taking the traffic characteristics of flows into account significantly improves the queuing delay performance when the flows have distinct characteristics.

Influence of Network Characteristics on Application Performance in a Grid Environment

In grid computing, a key issue is how limited network resources can be shared by communications by various applications more effectively in order to improve application-level performance, e.g., by reducing the completion time for an individual application and/or set of applications. Communication by an application changes the condition of the network resources, which may, in turn, affect communications by other applications, and thus may degrade their performance. In this paper, we examine the characteristics of traffic generated by typical grid applications, and the effect of the round-trip time and bottleneck bandwidth on the application-level performance (i.e., completion time) of these applications. Our experiments showed that the impact of network conditions on the performance of various applications and the impact of application traffic on network conditions differed considerably depending on the application. These results suggest that effective allocation of network resources must take into account the network-related properties of individual applications.

Redirection-Based Rules Sharing Method for the Scalable Management of Gateways in Mobile Network Virtualization

In this study, we propose a method for improving the scalability of sharing the flow rules, which are used to inspect and direct packets, between gateway functions in a mobile network virtualization infrastructure. The proposed method enhances the centralized management mechanism, where a controller reactively installs rules based on receiving the first packet of each flow, to reduce the load in the controller by decreasing the packets transmitted to the controller for packet inspection. The main feature of this method is that the gateway function redirects unknown packets to another gateway function instead of the controller, and the matched rules are installed in every gateway function on the redirection path using reverse-path forwarding. Using a simulation system, we showed that the enhanced method can reduce the number of packets arriving at the controller per unit time by ~ 62% under our use case assumption.