31501132
Optical switch configuration and lightpath assignment in wavelength routing multihop lightwave networks
A wide-area transparent optical network can be constructed by using wavelength routers and switches, each dealing with only a small number of wavelengths. In this work we consider the problem of configuring the wavelength routers based on the observed traffic. Various policies for wavelength routing, and the corresponding assignment of wavelengths along the routes have been studied before, which are based on minimizing congestion, average hop-distance, and call blocking probability or on maximizing carried traffic, and the number of clear channels. However these approaches often lead to scenarios where a significant number of available wavelengths at the input/output ports of the routers cannot be used due to potential wavelength conflict. The wavelength routing and assignment algorithms presented in this paper focus on maximizing the wavelength-utilization at the switching devices which also improve the overall network performance.
43624883
Algorithms for optimized node arrangements in ShuffleNet based multihop lightwave networks
The unique capabilities of lightwave technology are exploited in order to construct optimized regular multihop networks when the traffic flow among the network nodes is asymmetric. The specific problem addressed is as follows: given that the network nodes must be connected in a regular interconnection pattern and that the node positions in the regular network can be adjusted by properly tuning their (optical) transceivers, what is the best node placement in a given regular topology? In particular, the ShuffleNet-based regular topology is examined. ShuffleNet has the property of producing large connected graphs with small degree and diameter. In order words, it can interconnect a large number of nodes with a small number of transceivers per node such that information from a source can reach its destination in a small number of hops. Since finding the optimal node placement is a computationally hard problem, efficient heuristic algorithms are formulated to design optimized ShuffleNet structures for a given traffic matrix.<<ETX>>
17614044
Measurement Approaches to Evaluate Performance Optimizations for Wide-Area Wireless Networks
We present measurement approaches to evaluate performance optimizations, employed at different layers of the protocol stack, to enhance application performance over wide-area wireless networks (WWANs). Applications running over WWAN cellular environments (e.g web browsing) are significantly affected by the vagaries of the cellular wireless links. Much of the prior research has focussed on variety of isolated performance optimizations and their measurements over wired and wireless environments. In this paper we introduce experiment-based measurement approaches to benchmark application performance using optimizations performed at individual layers of the protocol stack.
3115897
A simple approximation for modeling nonstationary queues
Evaluation of the behavior of queues with nonstationary arrival processes is of importance in several applications including communication networks. However, the analysis of nonstationary queues is in general computationally complex and seldom produces closed form expressions. Thus approximation methods may be more appropriate. The pointwise stationary fluid flow approximation (PSFFA) for determining the mean queue length of nonstationary queues is presented. The PSFFA combines steady state queueing results with a simple fluid flow model to develop a single nonlinear differential equation model of the queue. Numerical integration techniques are used to solve the PSFFA model and the method is illustrated by several examples. The power of this approach is that it can handle very general queueing systems.
16504925
Debugging DHCP performance
Dynamic Host Configuration Protocol (DHCP) was defined to facilitate automatic configuration of IP addresses and other network parameters to hosts in a network. Efficiency of DHCP's address management is especially important today in part due to proliferation of mobile devices with transient network access patterns and the consequent increased demand on transient IP addresses in open-access networks. Unfortunately, DHCP's flexible design makes it susceptible to a variety of misconfigurations. The focus of this work is, therefore, to evaluate the performance and vulnerabilities of DHCP in operational networks today. To this end, we developed a tool called DHCP-Watch that facilitates DHCP-related network debugging and enables better capacity planning. We used this tool to perform a first-of-its-kind detailed measurement study of DHCP performance in operational university campus networks. Our measurements revealed various trends of IP address usage. Additionally, we discovered frequent anomalous operations due to network misconfigurations and presence of misbehaving hosts.
135907
Minimum energy reliable paths using unreliable wireless links
We address the problem of energy-efficient reliable wireless communication in the presence of unreliable or lossy wireless link layers in multi-hop wireless networks. Prior work [1] has provided an optimal energy efficient solution to this problem for the case where link layers implement perfect reliability. However, a more common scenario --- a link layer that is not perfectly reliable, was left as an open problem. In this paper we first present two centralized algorithms, BAMER and GAMER, that optimally solve the minimum energy reliable communication problem in presence of unreliable links. Subsequently we present a distributed algorithm, DAMER, that approximates the performance of the centralized algorithm and leads to significant performance improvement over existing single-path or multi-path based techniques.
20080343
A survey of adaptive bandwidth control algorithms
In packet-switched network traffic management and control, efficiently allocating bandwidth to provide quantitative packet-level QoS to aggregate traffic has been difficult due to unpredictable, unknown statistical characteristics of the aggregate traffic. With inaccurate traffic information, using static bandwidth allocation results in the network being underutilized, or the QoS requirement not being satisfied. An alternative is to use adaptive bandwidth control (ABC), whereby the allocated bandwidth is regularly adjusted over the packet-level time scale to attain a given QoS requirement. This paper provides a literature review of ABC algorithms that guarantee aggregate traffic packet-level QoS metrics, such as the average queue length, packet loss, and packet delay. We describe different ABC algorithms, identify their advantages and shortcomings, and provide some comparative performance evaluation results. Open issues in ABC for future research directions are also discussed.