Power and Memory Efficient Hashing Schemes for Some Network Applications

Hash tables (HTs) are used to implement various lookup schemes and they need to be efficient in terms of speed, space utilization, and power consumptions. For IP lookup, the hashing schemes are attractive due to their deterministic O(1) lookup performance and low power consumptions, in contrast to the TCAM and Trie based approaches. As the size of IP lookup table grows exponentially, scalable lookup performance is highly desirable. For next generation high-speed routers, this is a vital requirement when IP lookup remains in the critical data path and demands a predictable throughput. However, recently proposed hash schemes, like a Bloomier filter HT and a Fast HT (FHT) suffer from a number of flaws, including setup failures, update overheads, duplicate keys, and pointer overheads. In this dissertation, four novel hashing schemes and their architectures are proposed to address the above concerns by using pipelined Bloom filters and a Fingerprint filter which are designed for a memory-efficient approximate match. For IP lookups, two new hash schemes such as a Hierarchically Indexed Hash Table (HIHT) and Fingerprint-based Hash Table (FPHT) are introduced to achieve a a perfect match is assured without pointer overhead. Further, two hash mechanisms are also proposed to provide memory and power efficient lookup for packet processing applications. Among four proposed schemes, the HIHT and the FPHT schemes are evaluated for their performance and compared with TCAM and Trie based IP lookup schemes. Various sizes of IP lookup tables are considered to demonstrate scalability in terms of speed, memory use, and power consumptions. While an FPHT uses less memory than an HIHT, an FPHT-based IP lookup scheme reduces power consumption by a factor of 51 and requires 1.8 times memory compared to TCAM-based and trie-based IP lookup schemes, respectively. In dissertation, a multi-tiered packet classifier has been proposed that saves at most 3.2 times power compared to the existing parallel packet classifier. Intrinsic hashing schemes lack of high throughput, unlike partitioned Ternary Content Addressable Memory (TCAM)-based scheme that are capable of parallel lookups despite large power consumption. A hybrid CAM (HCAM) architecture has been introduced. Simulation results indicate HCAM to achieve the same throughput as contemporary schemes while it uses 2.8 times less memory and 3.6 times less power compared to the contemporary schemes

A Practical QoS Network Management System Considering Load Balancing of Resources

This paper presents a load balancing scheme for Multipath QoS Routing in QMulator which was created by UCLA and utilized for QoS network. With this multipath routing, QMulator has showed that it was ready to address the varied characteristics of traffic and can assure a high degree of adherence to the quality of service demand as well as the load balancing in the sense of scattering packets. But while implementing multipath routing, it didn't consider the whole network resources, such as link utilization or load balancing

A Hash-based scalable IP lookup using bloom and fingerprint filters

Abstract — Several challenges in the IP lookup architecture must be addressed for a high-speed forwarding in a large scale routing table: power, memory, and lookup complexity. Hashbased architectures have lookup schemes that are recognized for being both power and memory efficient due to their O(1) lookup, in contrast to other contemporary architectures. In this paper, we propose a novel hash architecture to address these issues by using pipelined Bloom and fingerprint filters for a binary searching in keys. The proposed hash scheme encodes keys ’ indexes to an on-chip fingerprint table, approximately returns a few indexes in a key query without pointer overhead, and makes a perfect matchinanoff-chip key table. Due to a memory banking system in pipeline stages, we can achieve O(1) pipelined throughput complexity of insertion, deletion, and query operations. For the IP lookup, a Lulea bitmap with our hash scheme supports a prefix lookup without inflating the numbers of prefixes and next-hops, so that our scalable hash-based scheme can achieve the worst case O(1) IP lookup. The simulation with large scale routing tables shows that our IP lookup scheme offers 4.5 and 50.1 times memory and power efficiencies than other contemporary hash and TCAM schemes, respectively. I

Wireless Sensor Networks

Abstract — Along with energy conservation, it has been a critical issue to maintain a desired degree of coverage in wireless sensor networks (WSNs), especially in a mobile environment. By enhancing a variant of Random Waypoint (RWP) model [1], we propose Mobility Resilient Coverage Control (MRCC) to assure K-coverage in the presence of mobility. Our basic goals are 1) to elaborate the probability of breaking K-coverage with moving-in and moving-out probabilities, and 2) to issue wake-up calls to sleeping sensors to meet user requirement of K-coverage even in the presence of mobility. Furthermore, by separating the mobility behavior into average and individual, the probability of breaking K-coverage can be precisely calculated, hence reducing the number of sensors to be awakened. Our experiments with NS2 show that MRCC with the individual probability achieves better coverage by 1.4 % with 22 % fewer numbers of active sensors than that of existing Coverage Configuration Protocol (CCP) [2]

QoS-aware Multiple Spanning Tree Mechanism over a Bridged LAN Environment

Today's emerging traffic is far removed from the traffic trends seen during the early days of Ethernet technology. As a result, the current IEEE 802.1 standards and its extensions to the Spanning Tree protocol fall short of providing satisfactory quality of service for traffic which has a significant amount of QoS-sensitive multimedia and VOIP traffic. In the current and near-future scenario of campus-wide networks with significantly large layer-2 clusters and numerous VLANs, we show significant shortcomings of the basic Spanning Tree and the Multiple Spanning Tree protocols with regard to QoS. We propose a novel, simple and yet highly effective enhancement to the Multiple Spanning Tree protocol to achieve high degree of QoS by keeping in perspective the different characteristics of the various traffic types in the Diffserv framework. We discuss the problems of the current standards and present in detail our proposed extension to overcome them. Our simulation results show up good improvement in throughput and significant benefits in delay for all classes of traffic to conclusively prove our claims

A cross-layer framework for wireless LAN QoS support

Abstract — The IEEE802.11x based wireless LAN technologies are leading the indoor Internet distribution in education, business and home environments. They are usually deployed as wireless extension of a broadband access to the network (i.e. DSL, cable modem, etc). These technologies are based on CSMA/CA media access with a positive MAC layer acknowledgement and a retransmission mechanism that aids noisy channel propagation condition and eventual undetected collisions. While TCP traffic benefits from a layer 2 retransmission policy the multimedia traffic experiences large delays and jitter resulting in a poor user experience. In this paper we satisfy the emerging user need of a MAC layer Quality of Service (QoS) support by taking advantage from layers 4-7 information. We believe the concepts and the architectural design presented are suitable to enhance QoS support in wireless technologies. I

A Cross-Layer Framework for Wireless LAN QoS Support

Absmcf-The IEEE802.11r based wireless LAN technologies are leading the indoor Internet distribution in education, business and home environments. They are usually deployed as wireless extension of a broadband aecess to the network (i.e. DSL, cable modem, etc). These technologies are based on CSMAICA media access with a positive MAC layer acknowledgement and a retransmission mechanism that aids noisy channel propagation condition and eventual undetected collisions. While TCP traffic benefits from a layer 2 retransmission poliey the multimedia traffic experiences large delays and jitter resulting in a poor user experience. In this paper we satisfy the emerging user need of a MAC layer Quality of Serviee (QoS) support by taking advantage from layers 4-7 information. We believe the concepts and the architectural design presented are suitable to enhance QoS support in wireless technologies. I