309943
Optimizing cost and performance for multihoming
Multihoming is often used by large enterprises and stub ISPs to connect to the Internet. In this paper, we design a series of novel smart routing algorithms to optimize cost and performance for multihomed users. We evaluate our algorithms through both analysis and extensive simulations based on realistic charging models, traffic demands, performance data, and network topologies. Our results suggest that these algorithms are very effective in minimizing cost and at the same time improving performance. We further examine the equilibrium performance of smart routing in a global setting and show that a smart routing user can improve its performance without adversely affecting other users.
920559
Verifiable distributed oblivious transfer and mobile agent security
The mobile agent is a fundamental building block of the mobile computing paradigm. In mobile agent security, oblivious transfer (OT) from a trusted party can be used to protect the agent's privacy and the hosts' privacy. In this paper, we introduce a new cryptographic primitive called Verifiable Distributed Oblivious Transfer (VDOT), which allows us to replace a single trusted party with a group of threshold trusted servers. The design of VDOT uses two novel techniques, consistency verification of encrypted secret shares and consistency verification through re-randomization. VDOT protects the privacy of both the sender and the receiver against malicious attacks of the servers. We also show the design of a system to apply VDOT to protect the privacy of mobile agents. Our design partitions an agent into the general portion and the security-sensitive portion. We also implement the key components of our system. As far as we know, this is the first effort to implement a system that protects the privacy of mobile agents. Our preliminary evaluation shows that protecting mobile agents not only is possible, but also can be implemented efficiently.
4407504
Optimal ISP subscription for Internet multihoming: algorithm design and implication analysis
Multihoming is a popular method used by large enterprises and stub ISPs to connect to the Internet to reduce cost and improve performance. Recently researchers have studied the potential benefits of multihoming and proposed protocols and algorithms to realize these benefits. They focus on how to dynamically select which ISPs to use for forwarding and receiving packets, and assume that the set of subscribed ISPs is given a priori. In practice, a user often has the freedom to choose which subset of ISPs among all available ISPs to subscribe to. We call the problem of how to choose the optimal set of ISPs the ISP subscription problem. In this paper, We design a dynamic programming algorithm to solve the ISP subscription problem optimally. We also design a more efficient algorithm for a large class of common pricing functions. Using real traffic traces and realistic pricing data, we show that our algorithm reduces users' cost. Next we study how ISPs respond to users' optimal ISP subscription by adjusting their pricing strategies. We call this problem the ISP pricing problem. Using a realistic charging model, we formulate the problem as a non-cooperative game. We first prove that if cost is the only criterion used by a user to determine which subset of ISPs to subscribe to, at any equilibrium all ISPs receive zero revenue. We then study a more practical formulation in which different ISPs provide different levels of reliability and users choose ISPs to both improve reliability and reduce cost. We analyze this problem and show that at any equilibrium an ISP's revenue is positive and determined by its reliability.
5645902
On designing incentive-compatible routing and forwarding protocols in wireless ad-hoc networks: an integrated approach using game theoretical and cryptographic techniques
In many applications, wireless ad-hoc networks are formed by devices belonging to independent users. Therefore, a challenging problem is how to provide incentives to stimulate cooperation. In this paper, we study ad-hoc games---the routing and packet forwarding games in wireless ad-hoc networks. Unlike previous work which focuses either on routing or on forwarding, this paper investigates both routing and forwarding. We first uncover an impossibility result---there does not exist a protocol such that following the protocol to always forward others' traffic is a dominant action. Then we define a novel solution concept called cooperation-optimal protocols. We present Corsac, a cooperation-optimal protocol consisting of a routing protocol and a forwarding protocol. The routing protocol of Corsac integrates VCG with a novel cryptographic technique to address the challenge in wireless ad-hoc networks that a link's cost (ie, its type) is determined by two nodes together. Corsac also applies efficient cryptographic techniques to design a forwarding protocol to enforce the routing decision, such that fulfilling the routing decision is the optimal action of each node in the sense that it brings the maximum utility to the node. Additionally, we extend our framework to a practical radio propagation model where a transmission is successful with a probability. We evaluate our protocols using simulations. Our evaluations demonstrate that our protocols provide incentives for nodes to forward packets.
3103973
Sprite: a simple, cheat-proof, credit-based system for mobile ad-hoc networks
Mobile ad hoc networking has been an active research area for several years. How to stimulate cooperation among selfish mobile nodes, however, is not well addressed yet. In this paper, we propose Sprite, a simple, cheat-proof, credit-based system for stimulating cooperation among selfish nodes in mobile ad hoc networks. Our system provides incentive for mobile nodes to cooperate and report actions honestly. Compared with previous approaches, our system does not require any tamper-proof hardware at any node. Furthermore, we present a formal model of our system and prove its properties. Evaluations of a prototype implementation show that the overhead of our system is small. Simulations and analysis show that mobile nodes can cooperate and forward each other's messages, unless the resource of each node is extremely low.
15017783
On the Computational Complexity of Sensor Network Localization
Determining the positions of the sensor nodes in a network is essential to many network functionalities such as routing, coverage and tracking, and event detection. The localization problem for sensor networks is to reconstruct the positions of all of the sensors in a network, given the distances between all pairs of sensors that are within some radius r of each other. In the past few years, many algorithms for solving the localization problem were proposed, without knowing the computational complexity of the problem. In this paper, we show that no polynomial-time algorithm can solve this problem in the worst case, even for sets of distance pairs for which a unique solution exists, unless RP = NP. We also discuss the consequences of our result and present open problems.
1977839
Effective classification of noisy data streams with attribute-oriented dynamic classifier selection
Recently, mining from data streams has become an important and challenging task for many real-world applications such as credit card fraud protection and sensor networking. One popular solution is to separate stream data into chunks, learn a base classifier from each chunk, and then integrate all base classifiers for effective classification. In this paper, we propose a new dynamic classifier selection (DCS) mechanism to integrate base classifiers for effective mining from data streams. The proposed algorithm dynamically selects a single “best” classifier to classify each test instance at run time. Our scheme uses statistical information from attribute values, and uses each attribute to partition the evaluation set into disjoint subsets, followed by a procedure that evaluates the classification accuracy of each base classifier on these subsets. Given a test instance, its attribute values determine the subsets that the similar instances in the evaluation set have constructed, and the classifier with the highest classification accuracy on those subsets is selected to classify the test instance. Experimental results and comparative studies demonstrate the efficiency and efficacy of our method. Such a DCS scheme appears to be promising in mining data streams with dramatic concept drifting or with a significant amount of noise, where the base classifiers are likely conflictive or have low confidence.
16965968
Performance of Full Text Search in Structured and Unstructured Peer-to-Peer Systems
While structured P2P systems (such as DHTs) are often regarded as an improvement over unstructured P2P systems (such as super-peer networks) in terms of routing efficiency, it is not clear which architecture is better for full text search. This paper provides a quantitative comparison of full text keyword search in structured and unstructured P2P systems. We examine three techniques (and optimizations to those techniques) proposed in the literature: using a DHT along with inverted lists and Bloom filters; using a super-peer network; and using a random walk over an unstructured network. We use real Web documents and user queries to measure the cost for both document publishing and query processing, in terms of bandwidth and response time. Our results show that all three techniques use roughly the same bandwidth to process queries (with the super-peer technique having a slight edge). The structured network provides the best response time (30 percent better than a super-peer network), but has a high cost of document publishing, using six times as much bandwidth as the super-peer system. The random walk technique requires no publishing, but has a very long response time unless multiple random walks operate in parallel.
4928164
A service workflow management framework based on peer-to-peer and agent technologies
Service workflow management which consolidates multiple services to achieve business goals has become a critical issue in service-oriented computing. Due to the unique feature of service workflows such as full distribution and high dynamicity, the contemporary workflow technology has exhibited inefficiency, vulnerability, inflexibility and lack of adaptability. Based upon the authors' previous work on peer-to-peer based workflow management and seamless integration of agents and Web services, this paper innovatively presents SwinDeW-A which is a decentralised service workflow management framework based on peer-to-peer and agent technologies. Based on this framework, this paper also discusses how autonomous service level agreement negotiation, decentralised process enactment, and autonomous process adaptation can be achieved. The proposed approach takes advantages of the peer-to-peer computing technology and the agent technology to provide more efficient, reliable, flexible and adaptive service workflow management.
58339956
IPsec/VPN security policy correctness and assurance
With IPsec/VPN policies being widely deployed, how to correctly specify and configure them is critical in enforcing security requirements, especially among different administrative domains across the Internet. Under current practice, IPsec/VPN policies are specified individually by system administrators from different organizations without any formal coordination. This practice implies unintentional errors due to inconsistent IPsec/VPN policies. Furthermore, Internet routing dynamics may possibly interfere with IPsec/VPN policies such that unexpected conflicts occur due to a mismatch between the routing and IPsec/VPN layers. To deal with these problems, we formally define IPsec security requirements, policies, and their correctness criteria. Based on these definitions, we present an inter-domain architecture to automatically generate correct and efficient security policies. Our approach works when we are given a set of security requirements for a single end-to-end traffic flow. We can also deal with changes when new security requirements are added. Finally, we present simulation results which evaluate the performance of our solutions.
599278
Extending RDF in distributed knowledge-intensive applications
The resource description framework (RDF) has become a formal language tool to specify the semantics of distributed systems, such as web services nowadays. In fact, it can also be extended to describe entities and relationships within specific application environments to support knowledge sharing and ontology construction. This paper presents two case studies on a network management knowledge model and a distributed workflow system process ontology. With practical experiences, the authors suggest how RDF can be applied innovatively and effectively to reengineer data integration solutions in different novel knowledge-intensive areas, which, in the past, were built upon traditional modelling languages, such as XML.