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Geographic variations in the dolphin whistles could be useful in assessing association and isolation among populations. Whistle of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) among the Pearl River Estuary (PRE), Leizhou Bei (LZB) and Sanniang Bay (SNB) populations were investigated. A total of 2850 whistles with legible fundamental contour were extracted and 15 acoustic parameters were measured. Contrary to SNB, PRE and LZB had the same relative proportion of tonal type compositions with flat and sine representing the most frequent types. The generalized linear model analysis showed significant acoustic difference among populations and tonal types. All frequency parameters in SNB were significantly higher than those in PRE and LZB, where no significant variation was observed in most of the parameters either at the population level or within each tonal type. Canonical discriminant functions analysis showed a smaller difference between PRE and LZB than between PRE and SNB and between LZB and SNB. Compared with previous recordings, recent recordings demonstrated a consistent pattern of becoming higher in whistle frequency parameters in both LZB and SNB populations, suggesting that noise pollution in LZB and SNB increasing with time according to the acoustic niche hypothesis. Dolphin whistle's geographic variations could be shaped by the combined function of the geographical barrier function of the Qiongzhou strait and local ambient noise. Considering the isolated condition and the relatively smaller population size of the humpback dolphin in the SNB, more effective and proactive conservation actions should be taken to prevent the extinction of small populations.

Stream control transport protocol (SCTP)-based concurrent multipath transfer (CMT) can help multi-homed devices to increase their throughput by making use of parallel transmissions over multiple paths and bandwidth aggregation. However, if CMT cannot identify wireless error, it cannot really achieve the desired performance. Furthermore, if CMT only utilizes all available paths for data delivery, it will undoubtedly degrade application-level performance since the asymmetric paths may involve large quality differences. This paper proposes a novel cross-layer quality-of-service (QoS)-aware adaptive CMT (CMT-CQA) with the following aims: (i) to provide an adaptive ‘CMT-to-partial CMT’ adjustment strategy for efficient bandwidth aggregation by jointly considering transport layer QoS, MAC layer QoS, and path history information; (ii) to address an enhanced congestion window (cwnd) fast recovery mechanism to reduce bursty transmission in multi-homed wireless network environments where fail-over occurs frequently; and (iii) to introduce a proper multimedia transmission behavior to improve users' quality of experience (QoE) for multimedia streaming service. Simulation results show that CMT-CQA outperforms the existing CMT solutions in terms of performance and QoS. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Named data networking NDN has attracted much attention on the design for next generation Internet architecture. Although it embeds some security primitives in its original architecture, it may suffer from denial-of-service DoS attacks. In this paper, we model one representative type of NDN-specific DoS attacks named DoS against pending interest table PIT, or DoS-PIT, which floods malicious Interests that request nonexistent content to bypass cached content at routers and to exhaust the memory resource for PIT, bringing in severe service degradation. In our proposed analytical model, the closed-form expressions for the DoS probability for users suffering DoS-PIT are derived, while considering several important factors of NDN networks such as PIT size, time-to-live of each PIT entry, popularity of content, and cache size. Moreover, extensive simulation experiments demonstrate the accuracy of the proposed model on evaluating the damage effect of DoS-PIT. In addition, the proposed model can be chosen to guide designing effective countermeasures for DoS-PIT or attacks with similar way to harm NDN by properly setting the values of some parameters e.g., cache size of each NDN router. Copyright © 2013 John Wiley & Sons, Ltd.

In this paper, we investigate the optimization of content router deployment in large-scale information centric core-edge separation Internet. We formulate the target cost function, which captures the trade-off between the cost for traffic transmission and cost due to additional deployment of content routers. To solve the problem, we first derive the analytical results of traffic ratio and its closed-form approximation. We then construct a convex optimization problem, from which the optimal deployment probability can be solved. By extensive numerical results, the accuracy of the closed-form approximation of traffic ratio is demonstrated. And, it is found that the optimal deployment probability is decided by the average number of hops for obtaining the content, the cost for traffic transmission, and the cost of extending router to content router. Copyright © 2013 John Wiley & Sons, Ltd.

The original architecture of content-centric network CCN may suffer from interest flooding attacks. In this paper, we focus on one type of interest flooding attacks called denial of service against content source DACS attack. To damage CCN, it floods a large number of malicious interests requesting content that does not exist, which guarantees that no cache hit can occur at routers until these malicious interests reach the target content source. Thus, it can directly exhaust the resource of the victim. To counter it, we propose a threshold-based detecting and mitigating TDM scheme. The basic idea is to detect DACS attack on the basis of the frequency that pending interest table items in CCN routers expire recording this frequency by introducing two counters with their corresponding thresholds and one indicator for counter mode and to mitigate it by implementing the rate limiter in each router. From the viewpoint of a CCN router, we analyze the performance of TDM in terms of detection ability and effect on mitigating malicious traffic. In addition, we briefly analyze the overhead of TDM. The results show that TDM achieves high detection ability and good effect on mitigating malicious traffic while bringing in small overhead on countering DACS attack. To the best of our knowledge, this is the first attempt to design a detailed scheme embedded with corresponding algorithms on countering this attack. Copyright © 2013 John Wiley & Sons, Ltd.

SUMMARY In networks with identifier/locator separation, border routers often cache recently used identifier-to-locator mappings of remote hosts and set a time to live (TTL) for each mapping. We consider two options to update the TTL of a mapping, designated as no-reset (NR) and with-reset (WR) modes. In the NR mode, once a mapping is cached, its TTL is set to a default value called cache timeout, and the mapping is removed when the TTL expires. By contrast, in the WR mode, whenever the mapping is queried, its TTL is reset to the cache timeout. Although it is not difficult to intuitively observe that the WR mode performs better than the NR mode in terms of cache hit rate, it is still of interest to evaluate what is the benefit gained by using the WR mode rather than the NR mode and what is the cost incurred to achieve this gain. Another equivalent question is what is the additional cost incurred in terms of resources for the NR mode to perform similarly to the WR mode. We model the cache hit rate and compare the performance of the WR and NR modes for flat and aggregatable identifiers by analysis and simulation, and estimate how much more cache size the NR mode requires to achieve similar cache hit rate and communication interruptions to the WR mode. The comparison results provide rational to use the WR mode, rather than the NR mode, for identifier-to-locator mapping caches. Copyright © 2012 John Wiley & Sons, Ltd.

SUMMARY In traditional Internet architectures, current centralized mobility management schemes face scalability issues because of the creation of network bottlenecks and a single mobility agent of failures. To address these issues, we propose a distributed mobility management scheme in locator/identifier separation networks (DMMLIS). We divide the network into many domains according to the area of autonomous systems. Each domain consists of a mapping server and several tunnel routers (xTRs). The mapping server stores global mappings between endpoint identifier (EID) prefixes and autonomous system numbers (ASNs) to lookup the mobile nodes' (MNs') home domain. Meanwhile, the mapping server also contains ASN-to-xTR mappings so that it can forward Map-Register and Map-Request messages to any xTR of the MN's home domain, thus enhancing reliability. In addition, the xTRs in each domain constitute one-hop distributed hash table ring. Moreover, any xTR in the MN's home domain may be the home agent of MNs, and the MNs' EID-to-RLOC (routing locator) mapping is stored in two xTRs using two hash functions. In this way, it not only supports quick lookup but also improves scalability and survivability. To evaluate the survivability and the efficiency of DMMLIS, we analyze the service blocking probability, the system response time, and the total protocol cost. We also present numerical results to demonstrate the performance of the proposed scheme. Copyright © 2012 John Wiley & Sons, Ltd.

SUMMARY The identifier/locator separation has been widely recognized as a feasible solution for addressing the current Internet's routing scaling problem. Moreover, such a separation solution in terms of mobility can keep connection survivability and support global seamless roaming. A critical challenge in supporting efficient mobility is how to update the identifier-to-locator mappings of mobile nodes (MNs). In this paper, we propose a mapping forwarding (MF) scheme for location management in the identifier/locator separation architecture. In the MF scheme, a tunnel router (xTR) is selected as an agent of an MN and keeps the MN's identifier-to-locator mapping invariable by setting up an MF chain. As long as the MN is managed by the same xTR, the MN's mapping stored in the xTR of each correspondent node of the MN does not need to be updated, thus reducing the location update signaling cost. Meanwhile, the unchanged mapping assures the correct forwarding of packets, which reduces mobility-related disruption and enhances the location management's reliability. In addition, for the handoff in two MF chains, we propose a data-triggered update scheme that can achieve route optimization. To evaluate the proposed MF scheme, we establish two analytical models and formulate the blocking probability and the total protocol cost. The performance results show how the blocking probability changes under various parameters and how the MF scheme can effectively reduce the blocking probability compared with the location management scheme without the MF strategy. Meanwhile, our analysis demonstrates that the MF scheme has a lower overhead when the mobility rate is high. Copyright © 2011 John Wiley & Sons, Ltd.

Distributed systems particularly suffer from Sybil attacks, where a malicious user creates numerous bogus nodes to influence the functions of the system. In this letter, we propose a Bloom filter-based scheme, SybilBF, to fight against Sybil attacks. A Bloom filter presents a set of Sybil nodes according to historical behavior, which can be disseminated to at least n·(e–1)/e honest nodes. Our evaluation shows that SybilBF outperforms state of the art mechanisms improving SybilLimit by a factor of (1/e)γ at least.

Mobile IPv6 (MIPv6) is a host-based mobility support specification which has been approved by the IETF as the standardized solution of global mobility management in IPv6 network for Mobile Node (MN). However, MIPv6 handover procedure results in a large handover delay. To improve its performance, some MIPv6 variants such as Fast Handover for MIPv6 (FMIPv6) and Hierarchical MIPv6 (HMIPv6) were proposed. However, they all require the MN to support the mobility management protocols which increase the difficulty of management and deployment. Recently, IETF NETLMM workgroup published the Proxy Mobile IPv6 (PMIPv6) which is a network-based localized mobility management to provide the mobility support for mobile host without the involvement of the mobility signaling. In this paper, we analyze the singling cost of PMIPv6 and implement it in our test-bed to evaluate its performance. The results show that the PMIPv6 has lower signaling cost and packet delivery cost, and it can improve the handover performance of UDP and TCP than the other mobility management protocols under low-delay networks, as for the wide area networks, it needs to introduce some mechanism like fast handover to further improve its performance. Copyright © 2009 John Wiley & Sons, Ltd.

Proxy mobile IPv6 (PMIPv6) is a network-based mobility protocol where the mobility management signaling is performed by a network entity on behalf of the node requiring mobility itself. To the best of our knowledge, no studies have been conducted in the area of proxy MIPv6 authentication method. This paper proposes an authentication method in proxy MIPv6. In addition to providing access authentication, the proposed authentication method prevents threats such as replay attack and key exposure. Also, we develop analytic models for the authentication latency and cost analysis. Then, the impacts of mobility and traffic parameters on the authentication cost and latency are analyzed, respectively. Copyright © 2008 John Wiley & Sons, Ltd.

It is difficult to give an accurate judgement of whether the traffic model fit the actual traffic. The traditional method is to compare the Hurst parameter, data histogram and autocorrelation function. The method of comparing Hurst parameter cannot give exact results and judgement. The method of comparing data histogram and autocorrelation only gives a qualitative judgement. Based on linear discriminant analysis we proposed a novel arithmetic. Utilizing this arithmetic we analysed some sets of data with large and little differences. We also analysed some sets of data generated by network simulator. The analysis result is accurate. Comparing with traditional method, this arithmetic is useful and can conveniently give an accurate judgement for complex network traffic trace. Copyright © 2005 John Wiley & Sons, Ltd.

Software‐defined network, which separates control plane from the underlying physical devices, has the advantages of global visibility and high flexibility. Among the most typical applications in software‐defined network, there is significant interest on classifying flows, especially for elephant flow detection. Previous studies show that detecting and rerouting elephant flows (flows that transfer significant amount of data) effectively can lead to a 113% improvement in aggregate throughput compared with the traditional routing. However, the threshold of the existing detection approach was preconfigured without the consideration of the rapidly changing traffic in data center networks. This phenomenon could cause high detection error rate. To address this problem, we propose an adaptive approach for elephant flow detection, which could efficiently identify elephant flows with low latency and low overhead. Particularly, to meet the demands of the traffic characteristics in data center networks, dynamical traffic learning algorithm is adopted to configure the threshold value real timely and dynamically. Numerical results and experimental tests show that the mean error rate of detection is only 4.61% and the maximum number of packet‐in messages is minimum compared to other methods.