Stuttgart, Univ., Diplomarb., 1999.

Berlin, Techn. Univ., Diss., 2009.

University, Diss.--Paderborn, 1996.

VANET (Vehicular Ad-hoc NETwork) is a subclass of MANET (Mobile Ad-hoc NETwork). Since nodes in a VANET are usually high-speed mobile vehicles, the network topology changes so fast that conventional routing protocols, especially those designed for quasi-static network topologies, do not work well in a VANET. Since vehicles with GPS receivers and Digital Map devices are now widespread, routing protocols based on real-time traffic conditions emerge. In the routing protocols, road intersections form the virtual backbone. In particular, there is a connection between two road intersections if packets were successfully delivered from one road intersection to the other in the recent past. To combat against high mobility, in this thesis, we propose a routing protocol based on real-time information on vehicular traffic. We use backup paths for improving the packet delivery ratio in VANETs.

In this paper, we present a new routing protocol which using the characteristic of Bluetooth on Bluetooth-based mobile ad hoc networks. After observing the existing ad hoc routing protocol, we found there exist some useless routing packets which was helpless to build the routing path and increasing the load of network. We present a new Bluetooth routing protocol (BRP) which use the limited routing table in master device to reducing the routing table size and routing packets. In the simulation results, we show that BRP can reduce the routing overhead in network and avoid to product useless routing packets.

This thesis studies the associative skew clock routing problem, which seeks a clock routing tree such that zero skew is preserved only within identified groups of sinks. Although the number of constraints is reduced, the problem becomes more difficult to solve due to the enlarged solution space. Perhaps, the only previous study used a very primitive delay model which could not handle difficult instances when sink groups are intermingled. We reuse existing techniques to solve this problem including difficult instances based on an improved delay model. Experimental results show that our algorithm can reduce the total clock routing wirelength by 9%–15% compared to greedy-DME, which is one of the best zero skew routing algorithms.

In this dissertation, we study methods for improving the routing performance of computer communication networks in dynamic environments. The dynamic environments we considered in this work include both network topology changes and traffic demand changes. In the first part, We propose a novel fast rerouting scheme for link state routing protocols. Link state routing protocols are widely used by today’s ISPs on their backbone networks. The global update based rerouting of link state protocols usually takes seconds to complete which affects real time applications like Voice over IP. In our scheme, usually, only routers directly connected to failed links are involved in rerouting. For other cases, only a small number of neighboring routers are also involved. Since our scheme calculates rerouting paths in advance, rerouting can be done faster than previous reactive approaches. The computation complexity of our scheme is less than previous proactive approaches. In the second part, we study Multihoming Route Control (MRC) that is a technology used by multihomed stub networks recently. By selecting ISPs with better quality, MRC can improve routing performance of stub networks significantly. We first study the stability issue of distributed MRC and propose two methods to avoid possible oscillations of traditional MRC. The first MRC method is based on “optimal routing”. The idea is to let the stub networks belonging to a same organization coordinate their MRC and thus avoid oscillations. The second method is based on “user-optimal routing”. The idea is to allow MRC devices to use multiple paths for traffic to one destination network and switch traffic between paths smoothly when path quality or the traffic matrix changes. A third MRC method we propose is for MRC of traffic consisting of TCP flows of different sizes on paths with bottlenecks of limited capacity. Based on analysis of quality characteristics of bottleneck links, we propose a greedy MRC approach that works in small timescales. Simulation results show that the proposed MRC method can greatly improve routing performance for the MRC sites as well as the overall routing performance of all sites in the network.

No description available.

This paper proposes an isolation layer -- a shim -- betweeninter-domain routing and packet forwarding. The job of this layer isto coordinate between Autonomous Systems (AS's) on when and how tomodify the forwarding state to ensure inter-domain routing loops donot cause forwarding loops. The benefits of a consistency layer aretwofold. First, it prevents the creation of transient inter-domainforwarding loops and the resulting packet loss, high latency, andconnection failures.Second, by taking the burden of forwarding consistency off theinter-domain routing protocol, it enables inter-domain routingprotocols with more complex convergence characteristics than BGP, suchas protocols that optimize route selection based on performance. Weoffer two possible designs for the consistency layer. We prove thatboth designs are free of forwarding loops and show they are easy todeploy in the current Internet.

Overlay routing has been successful as an incremental method to improve the current Internet routing by allowing users to select the Internet paths by themselves. By its nature, overlay routing has selfish behavior, which makes impact on the related components of the Internet routing. In this thesis, we study three interactions related to overlay routing. First, overlay routing changes the traffic patterns observed by the network operating side, which uses traffic engineering techniques to cope with the dynamic traffic demands. We improve this vertical interaction between overlay routing and traffic engineering. Secondly, the performance of overlay routing may be affected by the action of other coexisting overlays. An initial result on the horizontal interaction among multiple overlays is given. Lastly, within a single overlay network, overlay nodes can be regarded as independent decision makers, who act strategically to maximize individual gain. We design an incentive-based framework to achieve Pareto-optimality in the internal interaction of overlay routing.