Adaptive Load Sharing for Network Processors

A novel scheme for processing packets in a router is presented, which provides for load sharing among multiple network processors distributed within the router. It is complemented by a feedback control mechanism designed to prevent processor overload. Incoming traffic is scheduled to multiple processors based on a deterministic mapping. The mapping formula is derived from the robust hash routing (also known as the highest random weight - HRW) scheme, introduced in K.W. Ross, IEEE Network, 11(6), 1997, and D.G. Thaler et al., IEEE Trans. Networking, 6(1), 1998. No state information on individual flow mapping needs to be stored, but for each packet, a mapping function is computed over an identifier vector, a predefined set of fields in the packet. An adaptive extension to the HRW scheme is provided in order to cope with biased traffic patterns. We prove that our adaptation possesses the minimal disruption property with respect to the mapping and exploit that property in order to minimize the probability of flow reordering. Simulation results indicate that the scheme achieves significant improvements in processor utilization. A higher number of router interfaces can thus be supported with the same amount of processing power

A prototype publication service for the Internet2 DSI project

This thesis presents the development of a prototype publication service for I2-DSI project. The Internet2 Distributed Storage Infrastructure (I2-DSI) project is developing an open architecture for scalable, robust middleware that will enable wide-area replication services for the research and education communities. In the current phase, the project has a wide-area testbed of six large storage servers, each running a common profile of software that supports demonstration content channels. This paper presents the motivation for source-object replication architecture, the approach to replication adopted by I2-DSI, and our recent efforts to dynamically create and manage content channels in D2-DSI without a system administration's intervention. Thus, the channel publication service presented focuses on enhancing the usefulness of the I2-DSI replication service by allowing users to publish and manage their materials in an autonomous fashion

Satisfaction-based Query Load Balancing

International audienceWe consider the query allocation problem in open and large distributed information systems. Provider sources are heterogeneous, au tonomous, and have finite capacity to perform queries. A main objective in query allocation is to obtain good response time. Most of the work towards this objective has dealt with finding the most efficient providers. But little attention has been paid to satisfy the providers interest in performing certain queries. In this paper, we address both sides of the problem. We propose a query allocation approach which allows providers to express their intention to perform queries based on their preference and satisfaction. We compare our approach to both query load balancing and economic approaches. The experimentation results show that our approach yields high efficiency while supporting the providers' preferences in adequacy with the query load. Also, we show that our approach guarantees interesting queries to providers even under low arrival query rates. In the context of open distributed systems, our approach outperforms traditional query load balancing approaches as it encourages providers to stay in the system, thus preserving the full system capacity

Adaptive Load Sharing for Network Processors

A novel scheme for processing packets in a router is presented that provides load sharing among multiple network processors distributed within the router. It is complemented by a feedback control mechanism designed to prevent processor overload. Incoming traffic is scheduled to multiple processors based on a deterministic mapping. The mapping formula is derived from the robust hash routing (also known as the highest random weight - HRW) scheme, introduced in K.W.\ Ross, IEEE Network, 11(6), 1997, and D.G.\ Thaler et al., IEEE Trans.\ Networking, 6 (1), 1998. \emph{No state information} on individual flow mapping has to be stored, but for each packet, a mapping function is computed over an \emph{identifier vector}, a predefined set of fields in the packet. An \emph{adaptive extension} to the HRW scheme is provided to cope with biased traffic patterns. We prove that our adaptation possesses the \emph {minimal disruption property} with respect to the mapping and exploit that property to minimize the probability of flow reordering. Simulation results indicate that the scheme achieves significant improvements in processor utilization. A higher number of router interfaces can thus be supported with the same amount of processing power

Load sharing for multiprocessor network nodes

This thesis discusses techniques for sharing the processing load among multiple processing units within systems that act as nodes in a data communications network. Load-sharing techniques have been explored in the field of computer science for many years and their benefits are well known, including better utilization of processing capacity and enhanced system fault tolerance. We discuss deploying such methods in the specifics of the networking environment. We concentrate particularly on the data plane, or the data packet-processing tasks. After reviewing the main results in the fields of load sharing and multiprocessor networking systems architectures, we conduct a preparatory optimization study of a router system to gain better understanding of the optimization issues in a particular multiprocessor system. The main contribution of this thesis, the adaptive load-sharing method, is presented next. We first formulate the optimization problem of mapping packets to processors. The goal is to minimize the likelihood of flow reordering, while respecting certain system constraints, such as the acceptable probability of a packet loss. As we show that the task is an NP-complete problem, we propose a heuristic method that uses an adaptive hash-based mapping to assign packets to processors. We demonstrate its advantages and prove that the method adaptation policy possesses the key minimal disruption property with respect to the mapping. In other words, the adaptation results in a minimum number of flows being moved among processing units. Further on, the method is validated in an extensive set of simulations designed to imitate the networking environment. Finally, two sample applications, an architecture of a multiprotocol router and an implementation of a server load balancer on a network processor demonstrate the applicability of the method