Spatial Clustering for IP Multicast: Algorithms and an Application

We introduce spatial clustering of multicast group members as a mechanism to scale wide-area multicast-based applications. To motivate the use of such structures, we present a clustering based re-keying scheme for secure multicast. Using amortized analysis, we show that the communication, processing, and storage costs for this scheme to distribute keys upon membership changes is of constant order. This improves upon the previously known best-case logarithmic bounds under the same assumptions. Next, we develop a clustering algorithm and a cluster formation protocol that can be built atop IP multicast to create clusters with properties required to implement the secure multicast scheme. To show the viability of such a clustering scheme on the Internet, we present results from implementing this clustering technique on a Internet map of over 280,000 IP routers. We describe how a small set (~ 64) of multicast addresses can be used to efficiently implement intra-cluster communication in large groups (> 64K members). clustering protocol to demonstrate protocol robustness under varying membership dynamics

Self-Organizing Wide-Area Network Caches

A substantial fraction of all network traffic today comes from applications in which clients retrieve objects from servers. The caching of objects in locations "close" to clients is an important technique for reducing both network traffic and response time for such applications. In this paper we consider the benefits of associating caches with switching nodes throughout the network, rather than in a few hand-chosen locations. We also consider the use of various self-organizing or active cache management strategies for organizing cache content. We evaluate caching techniques using both simulation and a general analytic model for network caching. Our results indicate that in-network caching can make effective use of cache space. In particular, self-organizing caching schemes yield better average round-trip latencies than more traditional approaches, while requiring much smaller caches per node

Active networks : architectures, composition, and applications

Ph.D.Kenneth L. Calver

Application of an aqueous nanometric aluminum oxide suspension for fluoride remediation

A nanometric aluminum oxide suspension synthesized from AlCl3 (solution) has been discussed for its potential application as a low cost fluoride remediation system. The phase synthesized was identified as AlO (JCPDS card no: 75-0278) and e-Al2O3(JCPDS card no: 35-0121). The isoelectric point of the suspension was at pH 7.61. Optimum remediation pH was determined to lie in between 6.5 to 7.0. The maximum loading capacity was predicted to be 110 mg/g from Langmuir isotherm and 127 mg/g from Freundlich isotherm. Presence of interfering ions in a simulated real water matrix does not appreciably alter the remediation capacity. Eight real water samples were found to be effectively remediated with triplicate % r.s.d falling in between 0.1 to 1.3

Performance of Application-Specific Buffering Schemes for Active Networks

As the cost of computing power decreases and network traffic patterns become more complex, it becomes worthwhile to consider the benefits of allowing users to specify policies for managing their traffic within the network. Active networking is a new design paradigm in which the network is architected not merely to forward packets, but also to be dynamically programmed in order to support per-user services. Active networks export uniform "meta-level" interfaces that expose network-level resources, policies and mechanisms to its users. In this work, we present a new scheme for managing network buffer space, aggregate application level buffering, in which a group of flows of similar types are managed by an active node as a single entity. Thus, resources within the network are provisioned on a "per application" basis rather than a "per user" basis. We justify this scheme by comparing it to previously accepted buffering schemes such as a single shared buffer, per flow queueing, and an extension to per flow queueing which accommodates application specific packet dependencies. Within this work, we justify the benefits of this scheme in terms of required computational processing, information maintained by a node within a network, goodput achieved per application type, and mean delay. Based on the work herein, we show that the impact of an aggregate buffer management scheme can be significant depending on the interdependencies which may exist within an application's traffic stream

Bistro: a Framework for Building Scalable Wide-Area Upload

in the Internet. At the application layer, hot spots are usually caused by either (a) high demand for some data or (b) high demand for a certain service. This high demand for data or services, is typically the result of a real-life event involving availability of new data or approaching deadlines; therefore, relief of these hot spots may improve quality of life. At the application layer, hot spot problems have traditionally been dealt with using some combination of (1) increasing capacity; (2) spreading the load over time, space, or both; and (3) changing the workload