Large-scale layer-2 Ethernet networks are needed for important future and current applications and services including: metro Ethernet, wide area Ethernet, data center networks, cyber-physical systems, and large data processing. However Ethernet bridging was designed for small local area networks and suffers scalability and resiliency problems for large networks. I will present the architecture and protocols of ROME, a layer-2 network designed to be backwards compatible with Ethernet and scalable to tens of thousands of switches and millions of end hosts. We first design a scalable greedy routing protocol, Multi-hop Delaunay Triangulation (MDT) routing, for delivery guarantee on any connectivity graph with arbitrary node coordinates. To achieve near-optimal routing path for greedy routing, we then present the first layer-2 virtual positioning protocol, Virtual Position on Delaunay (VPoD). We then design a stateless multicast protocol, to support group communication such as VLAN while improving switch memory scalability. To achieve efficient host discovery, we present a novel distributed hash table, Delaunay DHT (D²HT). ROME also includes routing and host discovery protocols for a hierarchical network. ROME protocols completely eliminate broadcast. Extensive experimental results show that ROME protocols are efficient and scalable to metropolitan size. Furthermore, ROME protocols are highly resilient to network dynamics. The routing latency of ROME is only slightly higher than shortest-path latency. / text

As the field of Delay Tolerant Networking continues to expand and receive more attention, a new class of routing algorithms have been proposed that are specifically tailored to perform in a network where no end to end paths between devices are assumed to exist. As the number of proposed routing algorithms has grown, it has become difficult to fully understand their similarities and differences. Although published results clearly show different performance results between algorithms, it can be difficult to pinpoint which of their characteristics are most responsible for their performance differences. This thesis proposes an architectural framework to define the underlying features that Delay Tolerant Network routing algorithms are composed of. Popular routing algorithms from research are discussed and shown to be compositions of the proposed architectural features, thereby validating the architecture itself. The architectural framework is also shown to be a useful guide to developing a modular and configurable simulation platform. Algorithms from literature were implemented as a composition of features, which can easily be modified and combined later to define and implement new algorithms. Better understanding the underlying structure and similarities between different routing algorithm approaches is key to truly analyzing their performance and obtaining a deep understanding of which components of an algorithm have the most influence, both positively and negatively, on the results. Armed with this knowledge, designers of Delay Tolerant Networks can more easily determine the proper composition of routing algorithm features to best fit their needs. / text

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Multihop routing is an effective method for establishing connectivity between the nodes of a network. End-to-end outage probability and total power consumption are applied as the optimization criteria for routing protocol design in multihop networks based on the local channel state information measurement at the nodes of a network. The analysis shows that employing instantaneous channel state information in routing design results in significant performance improvement of multihop communication, e.g., achieving full diversity order when the optimization criterion is outage performance. The routing metrics derived from the optimization problems cannot be optimized in a distributed manner. Establishing an alternate framework, the metrics obtained are converted into new composite metrics, which satisfy the optimality and convergence requirements for implementation in distributed environments. The analysis shows that the running time of the proposed distributed algorithm is bounded by a polynomial. / Communications

In this work, we provide a qualitative comparison between existing geocast protocols and then we present an efficient geocast routing protocol for VANET. This protocol is a semantic and self-decision geocast routing protocol for disseminating safety and non-safety information over VANET (SAS-GP). SAS-PG initially executes an algorithm to locally determine the semantic geocast area. Then, the protocol disseminates the information in three phases: Spread, Preserve, and Assurance, which utilize the traffic information system and the digital map. SAS-GP principally employs timer-based techniques in order to avoid overhead and broadcast storm problems; nonetheless, novel factors are enhanced to calculate the timer’s values in each phase. Simulation results demonstrate effective and reliable dissemination in terms of delivery ratio and number of false warnings compared to existing protocols when evaluated in high scale and realistic scenarios. Also, SAS-GP performs faster in notifying vehicles resulting in a higher geocast distance before approaching the location of the event.

Prior research in routing for wireless ad hoc networks has shown that multipath routing can enhance data delivery reliability and provide load balancing. Nevertheless, only a few multipath routing algorithms have been proposed and their interaction with transport layer protocols has not been thoroughly addressed in the literature. In this work, we propose the multipath “Fresnel zone” routing (FZR) algorithm for wireless ad hoc networks. FZR constructs multiple parallel paths from source to destination based on the concept of “Fresnel zones” in a wireless network. The zone construction method assigns intermediate routers into different “Fresnel zones” according to their capacity and efficiency in forwarding traffic. The central idea in FZR is to disperse traffic to different zones according to network load and congestion conditions, thus achieving better throughput and avoiding congestion at intermediate routers. FZR differs from most existing multipath routing approaches in that both source and intermediate nodes use multiple forwarding paths. FZR also adopts a combination of proactive and on-demand (reactive) approaches to reduce control overhead and latency for packet delivery. Simulation experiments have shown that FZR outperforms unipath distance vector routing, multipath distance vector (MDV) routing, and split multipath routing (SMR) algorithms in quasistatic wireless ad hoc networks. In our simulations, FZR achieves up to 100 percent higher average throughput using the User Datagram Protocol (UDP) and 50 percent higher average throughput using the Transmission Control Protocol (TCP). FZR can also provide better load balancing among different paths, improve network resource utilization, and enable fairer resource allocation among different data transmission sessions. Future work is needed to evaluate FZR in mobile scenarios. / Master of Science

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