this paper, we propose using multipath routing to increase resilience to node failure. Multipath routing techniques have been discussed in the literature for several years now (Section V). However, the application of multipath routing to sensor networks and other systems that permit data-centric routing with localized path setup has not yet been explored. We consider two different approaches to constructing multipaths between two nodes. One is the classical node-disjoint multipath adopted by prior work, where the alternate paths do not intersect the original path (or each other). The disjoint property ensures that, when k alternate paths are constructed, no set of k node failures can eliminate all the paths. The other approach abandons the requirement for disjoint paths and instead builds many braided paths. With braided paths, there are typically no completely disjoint paths but rather many partially disjoint alternate paths

Several architectures have been recently proposed to support IP mobility. Most studies, however, show that current protocols, in general, fall short from satisfying the performance requirements for audio applications. In this study, we propose a multicast-based protocol to reduce latency and packet loss during handoff and provide the base for IP mobility support. We use extensive simulation to evaluate our protocol's performance over a variety of real and generated topologies, and we compare it to several other mobility protocols, especially the Mobile IP protocols. We take handoff delay estimates and routing efficiency as metrics for our comparisons. We take a route analysis (as opposed to packet analysis) approach in our study, and we apply it in the context of wide-area networks. Our simulation results show significant improvement for our proposed protocol. On average, basic Mobile IP consumes almost twice as much network bandwidth, and experiences more than twice as much end-to-end and handoff delays, as does our proposed protocol. In addition, average handoff delay estimates for our protocol prove to be less than that for other protocols in this study, even with route optimization. We further propose an extension to Mobile IP to support our protocol with minimal modification. Keywords Mobility, Multicast, Efficient Handoff, Network Simulation. 1.

Recently there have been several papers examining aspects of the Internet topology. This paper follows in that tradition and addresses two issues related to Internet topology. First, we use three properties -- expansion, resilience, and distortion -- to characterize real and generated networks. For these metrics, we find that existing network topology generators differ qualitatively from most real networks. Second, we ask what impact topology has on four different multicast design questions. We find that, for many of these questions, a single topology metric appears to influence the answer.

One of the main problems of the current Internet infrastructure is its inability to provide services at consistent QoS levels. At the same time, many emerging Internet applications, such as tele-education, and tele-conferencing, require multicast protocols that will provide the necessary Quality of Service (QoS). In this paper, we propose QoSMIC, a multicast routing protocol for the Internet, that provides QoS-sensitive paths in a scalable, resource-efficient and flexible way. QoSMIC differs from the previous protocols in that it identifies multiple paths and selects the one that can provide the required QoS. Two other key advantages of QoSMIC are its exibility and adaptivity. First, the distribution tree does not have to be rooted at a pre-selected core router. Second, we can trade-off between efficiency metrics depending on our needs; for example we can trade-off routing efficiency for a reduction in the control messages. Extensive simulations show that our protocol improves the resources utilization and the end-to-end performance compared to the current protocols. Specifically, our protocol reduces the call blocking probability by a factor of six and reduces the end-to-end delay by as much as 90% compared to the PIM protocol.

We propose intra-domain multicast-based mobility as a solution for IP mobility. Our architecture addresses problems with existing IP mobility proposals; mainly scalability and handoff performance. In our scheme mobility proxies are used to allocate per-domain multicast addresses to mobiles for use in micro mobility. State aggregation is studied as an essential element to improve scalability of our approach. We introduce a simple, yet very efficient aggregation algorithm, based on bitwise lossy aggregation. An important result obtained indicates that state tends to be concentrated in less than 20% of the nodes and that our scheme is extremely efficient in reducing the state in those nodes. We show that our scheme achieves much higher aggregation gain than conventional prefix-based aggregation.

This document gives an overview of most of the directions taken by research in the multicast area. We first introduce the basic concepts. The following sections deal with high level services that can (or must) be provided on top of the underlying multicast routing infrastructure. Then we consider new evolutions in multicast routing: new protocols, their large scale deployment, and future trends. Finally we discuss multicast tools and applications.

Recent work on differentiated services in the Internet has defined new notions of QoS that apply to aggregates of traffic in networks with coarse spatial granularity. Most proposals for differentiated services involve traffic control algorithms for aggregate service levels, packet marking and policing, and preferential treatment of marked packets in the network core. The issue of routing for enhancing aggregate QoS has not received a lot of attention. This study investigates the potential benefit of using alternate routing strategies in support of differentiated services. We propose a traffic control scheme, called Simple Alternate Routing (SAR), wherein portions of marked packet flows can be assigned to alternate paths through a Service Provider Network (SPN) in response to congestion feedback information. The scheme is simple, requiring only minor changes to the SPN border routers so that alternately routed packets can be tunneled via conventional paths to an intermediate bo...

Abstract—In this paper, we study the evolution of the Internet topology over the last three years. We study the evolution at three different levels: a) each node individually, b) the network as a whole, c) the path level. First, we find that the degrees of the nodes increase in a “rich get richer” fashion: the increase is proportional to the degree of the node. Second, we identify that new edges prefer nodes that have high degree of connectivity. Third, we observe a “small world ” phenomenon: the network grows exponentially, but distances remain the same. Fourth, we find that the routing inflation increases over time.

This research used a custom event-driven network simulator to evaluate Alternate Path Routing's (APR's) behavior in Mobile Ad Hoc Networks (MANETs). In particular, it investigated how much route-diversity is inherent in typical ad-hoc networks, and the ability of a globally reactive routing-protocol (such as the Zone Routing Protocol) to capture and utilize that route diversity. It then explored the end-to-end capacity improvements provided by APR. Results indicate that APR's benefit is highly dependent on both the network topology and the channel access methods.

QoS support poses new challenges to multicast routing especially for inter-domain multicast where network QoS characteristics will not be readily available as in intra-domain multicast. Several existing proposals attempt to build QoS-sensitive multicast trees by providing multiple joining paths for a new member using a flooding-based search strategy which has the draw-back of excessive overhead and may not be able to determine which join path is QoS feasible sometimes.