38 research outputs found
Umpiring security Models for MANETS
Get PDFIn wireless mobile ad hoc networks, packet delivery is achieved through two closely related network-layer operations: ad hoc routing and packet forwarding. As a result any security solution should encompass the protection of both. Protecting the network layer operations such as routing the control messages and data packet forwarding, from malicious attacks is an important and challenging issue in both wired and wireless mobile networks and the issue becomes even more challenging in the case of wireless mobile ad hoc network. Malicious nodes may disrupt routing algorithms by transmitting a false hop count; by dropping data packets and by routing the packets through unintended routes and so on. The work presented in this thesis attempts to improve the performance of wireless mobile ad hoc networks by protecting the network layer. Five studies are presented.Resumen de tesis doctoral presentada por el autor.Facultad de Informátic
An Efficient Framework of Congestion Control for Next-Generation Networks
Get PDFThe success of the Internet can partly be attributed to the congestion control algorithm in the Transmission Control Protocol (TCP). However, with the tremendous increase in the diversity of networked systems and applications, TCP performance limitations are becoming increasingly problematic and the need for new transport protocol designs has become increasingly important.Prior research has focused on the design of either end-to-end protocols (e.g., CUBIC) that rely on implicit congestion signals such as loss and/or delay or network-based protocols (e.g., XCP) that use precise per-flow feedback from the network. While the former category of schemes haveperformance limitations, the latter are hard to deploy, can introduce high per-packet overhead, and open up new security challenges. This dissertation explores the middle ground between these designs and makes four contributions. First, we study the interplay between performance and feedback in congestion control protocols. We argue that congestion feedback in the form of aggregate load can provide the richness needed to meet the challenges of next-generation networks and applications. Second, we present the design, analysis, and evaluation of an efficient framework for congestion control called Binary Marking Congestion Control (BMCC). BMCC uses aggregate load feedback to achieve efficient and fair bandwidth allocations on high bandwidth-delaynetworks while minimizing packet loss rates and average queue length. BMCC reduces flow completiontimes by up to 4x over TCP and uses only the existing Explicit Congestion Notification bits.Next, we consider the incremental deployment of BMCC. We study the bandwidth sharing properties of BMCC and TCP over different partial deployment scenarios. We then present algorithms for ensuring safe co-existence of BMCC and TCP on the Internet. Finally, we consider the performance of BMCC over Wireless LANs. We show that the time-varying nature of the capacity of a WLAN can lead to significant performance issues for protocols that require capacity estimates for feedback computation. Using a simple model we characterize the capacity of a WLAN and propose the usage of the average service rate experienced by network layer packets as an estimate for capacity. Through extensive evaluation, we show that the resulting estimates provide good performance
March 15, 2001
Get PDFThe Breeze is the student newspaper of James Madison University in Harrisonburg, Virginia
