A simple list (no abstracts) of technical reports is also available.
Yechiam Yemini and Danilo Florisi
(Thesis) German Goldszmidt
J,Sairamesh, D. Ferguson, and Y. Yemini, Proceedings of INFOCOM'95.
In this paper, we propose a new methodology based on economic models to provide Quality of Service (QoS) guarantees to competing traffic classes (classes of sessions) in packet networks. We consider an economic model of a packet network where resources are priced. Traffic classes compete for network resources and they purchase them to satisfy their QoS needs. Our contributions are the following: 1) We provide a new definition for QoS provisioning based on economic models (Pareto efficiency). 2) We obtain the set of optimal resource allocation (Pareto optimal) which provide QoS guarantees to competing traffic classes. 3) We show the impact on equilibrium prices and optimal allocations due to traffic load and variability, and QoS requirements. 4) We propose packet scheduling and admission policies to provide QoS guarantees to traffic classes based on available QoS and prices in the network.
(Thesis) Patricia Gomes-Soares Florissi
(Thesis) Danilo Florissi
Patricia Gomes-Soares Florissi and Yechiam Yemini
This paper proposes a new language for the development of distributed multimedia applications: Quality Assurance Language (QuAL). QuAL abstractions allow the specification of Quality of Service (QoS) constraints expected from the underlying computing and communication environment. QuAL specifications are compiled into run time components that monitor the actual QoS delivered. Upon QoS violations, application provided exception handlers are signaled to act upon the faulty events. Language level abstractions of QoS shelter programs from the heterogeneity of underlying infrastructures. This simplifies the development and maintenance of mul- timedia applications and promotes their portability and reuse. QuAL generates Management Information Bases (MIBs) that contain QoS statistics per application. Such MIBs may be used to integrate application level QoS management into standard network management frameworks.
Danilo Florissi and Yechiam Yemini
This paper overviews a novel transfer mode for B-ISDN: Loosely-synchronous Transfer Mode (LTM). LTM operates by signaling periphery nodes when destinations become available. No frame structure is imposed by LTM, thus avoiding adaptation layers. Additionally, LTM can deliver a spectrum of guaranteed quality of services. New Synchronous Protocol Stacks (SPSs) build on LTM by synchronizing their activities to LTM signals. Such signals can be delivered directly to applications that may synchronize its operations to transmissions, thus minimizing buffering due to synchronization mismatches. SPSs can use current transport protocols unchanged and, potentially, enhance them with the real-time capabilities made possible through LTM.
(Thesis Proposal) Patricia Gomes-Soares Florissii
Distributed multimedia applications are sensitive to the Quality of Services (QoS) provided by their computing and communication environment. For example, scheduling of processing activities or network queueing delays may cause excessive jitter in a speech stream, rendering it difficult to understand. It is thus important to establish effective technologies to ensure delivery of QoS required by distributed multimedia applications. This proposal presents a new language for the development of distributed multimedia applications: Quality Assurance Language (QuAL). QuAL abstractions allow the specification of QoS constraints expected from the underlying computing and communication environment. QuAL specifications are compiled into run time components that monitor the actual QoS delivered. Upon QoS violations, application provided exception handlers are signaled to act upon the faulty events. Language level abstractions of QoS shelter programs from the heterogeneity of underlying infrastructures. This simplifies the development and maintenance of multimedia applications and promotes their portability and reuse. QuAL generates Management Information Bases (MIBs) that contain QoS statistics per application. Such MIBs may be used to integrate application level QoS management into standard network management frameworks.
(Thesis Proposal) Danilo Florissi
Traditional switching techniques need hundred- or thousand-MIPS processing power within switches to support Gbit/s transmission rates available today. These techniques anchor their decision-making on control information within transmitted frames and thus must resolve routes at the speed in which frames are being pumped into switches. Isochronets can potentially switch at any transmission rate by making switching decisions independent of frame contents. Isochronets divide network bandwidth among routing trees, a technique called Route Division Multiple Access (RDMA). Frames access network resources through the appropriate routing tree to the destination. Frame structures are irrelevant for switching decisions. Consequently, Isochronets can support multiple framing protocols without adaptation layers and are strong candidates for all-optical implementations. All network-layer functions are reduced to an admission control mechanism designed to provide quality of service (QOS) guarantees for multiple classes of traffic. The main results of this work are: (1) A new network architecture suitable for high-speed transmissions; (2) An implementation of Isochronets using cheap off-the-shelf components; (3) A comparison of RDMA with more traditional switching techniques, such as Packet Switching and Circuit Switching; (4) New protocols necessary for Isochronet operations; and (5) Use of Isochronet techniques at higher layers of the protocol stack (in particular, we show how Isochronet techniques may solve routing problems in ATM networks).
Yechiam Yemini and Danilo Florissi
This paper overviews a novel switching architecture for high-speed networks: Isochronets. Isochronets time-divide network bandwidth among routing trees. Traffic moves down a routing tree to the root during its time band. Network functions such as routing and flow control are entirely governed by band timers and require no processing of frame headers bits. Frame motions need not be delayed for switch processing, allowing Isochronets to scale over a large spectrum of transmission speeds and support all-optical implementations. The network functions as a media-access layer that can support multiple framing protocols simultaneously, handled by higher layers at the periphery. Internetworking is reduced to a simple media-layer bridging. Isochronets provide flexible quality of service control and multicasting through allocation of bands to routing trees. They can be tuned to span a spectrum of performance behaviors outperforming both circuit or packet switching.
Ouri Wolfson, Soumitra Sengupta, and Yechiam Yemini
This paper has two purposes. First is to propose new database language features for systems used in real time management. These features enable the specification of change-traces, events and correlation among events, and they do so in a declarative set-oriented fashion. Second is to introduce network management as an important and interesting application of active distributed databases.
Ouri Wolfson, Hasanat Dewan, Salvatore Stolfo, and Yechiam
Yemini Rule interpreters usually start with an initial database and perform the inference procedure in cycles, ending with a final database. In a real time environment it is possible to receive updates to the initial database after the inference procedure has started or even after it has ended. We present an algorithm for incremental maintenance of the inference database in the presence of such updates. Interestingly, the same algorithm is useful for parallel and distributed rule processing. When the processors evaluating a program operate asynchronously, then they may have different {\em views} of the database. The incremental maintenance procedure we present can be used to synchronize these views.
Eugene Pinsky, Paul Fahn, and Yechiam Yemini
Many optimization problems in finance are known to be computationally complex. In this paper we consider one such problem of Mortgage Pool Allocation. In this problem one needs to allocate a set of mortgage-backed securities to fill forward contracts in real-time. The number of securities and contracts is typically large and there are numerous constraints on allocations in the form of rules published by the Public Securities Association (PSA). The problem is to find the most profitable allocation that satisfies all of the PSA's constraints. Simulated annealing is a recently explored probabilistic algorithm, used most commonly to solve simply-formulated combinatorial optimization problems with a small number of constraints. This paper shows successful application of simulated annealing to the problem of mortgage pool allocation: it finds good (highly profitable) solutions very quickly. This result is significant both for the complexity of the problem solved and because it demonstrates the feasibility of simulated annealing for solving real-world financial problems.