Connection Setup Research Articles

Universal multimedia access from wired and wireless systems

Personal computing and communication devices such as computers, personal digital assistants (PDAs), and mobile phones are moving to their next generation in which the end user will be able to access a multitude of information with a single device either locally or through a network. One likely trend in future personal computing and personal communication is that there will not be a single but several equivalent devices available to users allowing access to information in various forms. Each user, depending on his/her needs would access one or several among them depending on the situation and his/her preference. Using existing protocol mechanisms, in this case, a mapping and negotiation of resources during connection setup would be performed, which would remain in place throughout the life of the connection. This paper provides an overview of universal multimedia access (UMA), a concept for accessing multimedia content through a variety of possible schemes, and discusses some of the issues that arise regarding its deployment. In particular, UMA will provide a solution for adapting the delivered content when users attempt to access their choice irrespective of their terminal characteristics and communication infrastructure, as apposed to the assumption that the content remains fixed and the objective is to deliver the original content at all times. This recognition represents the impetus for the development of media descriptions and hence UMA; that is, the notion that valuable information can be derived from a variety of conversions of a multimedia content source. The issues discussed are future requirements on content servers and multimedia viewers, media conversions, UMA protocols, and UMA network architectures. The problems addressed are quality of service issues in network solutions for multimedia communications and reconfigurable architectures and network control based on source adaptations through media conversions and transcoding.

An integrated routing and admission control mechanism for real‐time multicast connection establishment

AbstractThere are two major difficulties in real‐time multicast connection setup. One is the design of an efficient distributed routing algorithm which optimizes the network cost of routing trees under the real‐time constraints. The other is the integration of routing with admission control into one single phase of operations. This paper presents a real‐time multicast connection setup mechanism, which integrates multicast routing with real‐time admission control. The proposed mechanism performs the real‐time admission tests on a cost optimal tree (COT) and a shortest path tree (SPT) in parallel, aiming at optimizing network cost of the routing tree under real‐time constraints. It has the following important features: (1) it is fully distributed; (2) it achieves sub‐optimal network cost of routing trees; (3) it takes less time and less network messages for a connection setup. Copyright © 2001 John Wiley & Sons, Ltd.

Correctness and performance of the ATM ABR rate control scheme

We study both correctness and performance of the source/destination protocols of the available bit rate (ABR) service in asynchronous transfer mode (ATM) networks. Although the basic protocol for rate-based congestion management is relatively simple, the protocol specification has to cope with several “real-world” cases such as failures and delayed/lost feedback which introduce complexity. Rigorous proof of the correct functioning of the protocol based on a formal specification is necessary. We use a formal model to show that the ABR source/destination protocol is free of livelocks, so that under all conditions both resource management (RM) and data cells will be transmitted. Furthermore, if there are data cells available, then the ABR protocol is deadlock free; otherwise, the system goes to a desirable sleep state waiting for data cells, as long as certain parameters are set appropriately at connection setup. We also show that the network options of explicit forward congestion indication (EFCI) and explicit rate (ER) interoperate correctly. In addition to ensuring the correct functioning of the protocol, it is essential that pathological situations do not result in very poor performance, which we view as another form of “incorrect operation”. We derive conditions that ensure that the source's allowed cell rate (ACR) is stable in the presence of delayed or lost feedback RM cells. We arrive at bounds on the number of consecutive RM cell losses tolerated while the ACR rate remains stable. We also provide an asymptotic estimate of ACR and the allowable RM cell loss probability to ensure that ACR is stable, statistically. The ABR protocol contributes to the feedback delay in two ways: the source delay of sending out the probe forward RM (FRM) cells and the destination delay of turning around the backward RM (BRM) cell. We provide a worst-case analysis of the delay in turning around RM cells at the destination station and the worst-case inter-departure time of FRM cells from the source.

Restorable VP-layout design in ATM networks for efficient support for multicast traffic

The authors present a new network design problem that is applicable for designing restorable virtual paths (VPs) in an asynchronous transfer mode (ATM) network to efficiently support multicast applications. They decompose the design procedure into two main phases: working VP layout (VPL) and backup VPL design phases. For the working VPL design phase, the design objective is to minimise the network overhead for the connection setup, routing table resources and control and management cost subject to the physical constraints. A heuristic is proposed to obtain a good working VPL. Based on the designed working VPL, a backup VPL is designed for restoring the connections in case of link failure in the second design phase. The design objective is to minimise the spare capacity cost. Two backup VPL design schemes, namely link-based backup VPL and tree-based backup VPL, are proposed to achieve a sub-optimal solution for backup VPL design. The tree-based scheme has a better spare capacity performance, while the link-based scheme has a shorter restoration time and a lower computing complexity. Simulations are performed on randomly generated networks and traffic demand patterns to demonstrate the performance and scalability of the solution.

Routing Mechanisms Employing Adaptive Weight Functions for Shortest Path Routing in Optical WDM Networks

Optical dense wavelength division multiplexed (DWDM) networks are an attractive candidate for the next generation Internet and beyond. In this paper, we consider routing and wavelength assignment in a wide area wavelength routed backbone network that employs circuit-switching. When a session request is received by the network, the routing and wavelength assignment (RWA) task is to establish a lightpath between the source and destination. That is, determine a suitable path and assign a set of wavelengths for the links on this path. We consider a link state protocol approach and use Dijkstra’s shortest path algorithm, suitably modified for DWDM networks, for computing the shortest paths. In [1] we proposed WDM aware weight functions that included factors such as available wavelengths per link, total wavelengths per link. In this paper, we present new weight functions that exploit the strong correlation between blocking probability and number of hops involved in connection setup to increase the performance of the network. We also consider alternate path routing that computes the alternate paths based on WDM aware weight functions. The impact of the weight functions on the blocking probability and delay is studied through discrete event simulation. The system parameters varied include number of network nodes, wavelengths, degree of wavelength conversion, and load. The results show that the weight function that incorporates both hop count and available wavelength provides the best performance in terms of blocking probability.

An integrated routing and admission control mechanism for real-time multicast connections in ATM networks

This letter presents: 1) a delay analysis model, which is specially for the admission control of real-time multicast connections in ATM networks; 2) a distributed multicast routing algorithm, which generates suboptimal routing trees under real-time constraints; and 3) a connection setup method that integrates multicast routing with admission control.

Analytical model for a WDM optical cross-connect with limited conversion capability

We introduce a general model for describing the connection setup in various wavelength-routing optical cross-connects with limited conversion capability. It enables us to determine if a given connection pattern can be supported, and to calculate the blocking performance of the cross-connects.

Optimization of hierarchical routing protocols

This paper concentrates on hierarchical routing protocols and their optimization. In a hierarchical routing protocol the network is divided into independent routing areas so that a node has complete routing information on its partition, but only reduced routing information of the “outside world” (i.e. the other partitions). Such routing protocols have been introduced in the early 1980s in order to decrease the overhead of dynamic routing protocols in large networks. However, such an approach may degrade the network performance. The aim of this work is to understand and quantify some aspects of the influence of this clustering process on network performance, and to determine how a given network (of a given topology) should be clustered under some optimization criteria. This problem has been already considered in the past, using a deterministic worst-case approach, for different optimization criteria. We generalize and refine the known results using a random geometric approach. This framework allows us to calculate explicitly the averages of various relevant variables (such as the size of the routing table and connection set-up latency) as a function of the topological parameters (such as the number of hierarchical levels). Optimum structures are then easily deduced.

Reducing database sizes in implicit deregistration for personal communication networks

Mobility management schemes that reduce signaling traffic load and connection setup time play a pivotal role in designing future personal communication services (PCS) network. It concerns users' Quality of Service (QoS) requirements and the efficient use of network resources. In recent years, many mobility management schemes have been proposed for the reduction of signaling traffic and network load. Regardless of the specific protocol, all such technologies must support two fundamental mechanisms. One is location management (knowing where the users are) and the other is handover management (making the transition between cells smooth). In location management, a mobile user has to register when entering a new registration area (RA) and to deregister when leaving. To reduce the signaling cost in registration and deregistration, Lin and Noerpel proposed an implicit deregistration scheme. That is, a mobile will not perform deregistration when leaving a RA. As a result, there are two consequences. First, we need a large registration database. Second, even with a large database, it will become full eventually. Then we have to select a record to delete when a new mobile moves into the RA. In the original implicit deregistration scheme, the oldest record is deleted. In this paper, we propose two more reasonable and effective criteria to determine which record should be deleted from the database when a new mobile moves into an RA and the database is full. The purpose is to decrease the database size and ensure a low probability that a valid record will be replaced at the same time. The two parameters used are call-to-mobility ratio (CMR) and average call arrival interval. When the database is full, the proposed method will delete the record that has the lowest CMR or that will have to wait for the longest time for an expected call arrival. Simulation results show that the modified approach has significant improvements on the database sizes.

Performance comparison of layer 3 switches in cases of flow- and topology-driven connection setup

The layer 3 switch enables us to transmit IP datagrams fast using the cut-through technique. There are mainly two cases in establishing connections; one is the flow-driven case and the other is the topology-driven one. In this paper, we analyze the cut-through rate, the datagram waiting time and the mis-order rate as performance measure of both cases and compare these performances. In the analysis, by using interrupted Bernoulli process (IBP), we model the arrival process of IP flow and IP datagram from each source. Furthermore, we investigate impacts of the arrival rate and the average IP flow length on the performance.

Connecting to the Internet: The Challenge for Canada's County and Regional Libraries

A previous survey, in 1995, revealed that only 3% of Canada's regional and county library systems provided public Internet access. The present survey showed that 67% of these libraries provided access and that connectivity was proceeding rapidly despite the geographical, technical, and financial difficulties faced by systems with large geographical areas and numerous members from different municipal or county jurisdictions. Library directors indicated that using the World Wide Web as a reference tool was the most useful staff application of the Internet and that this function was most appreciated in small branches located far from adequate reference collections. Funding for initial connectivity set-up costs came mainly from federal and provincial grants and from existing library budgets. Directors expected library budgets to be the primary funding source for ongoing Internet costs, a potentially difficult situation because of continuing fiscal shortfalls and increasing technical expenses. The Internet has ameliorated some of the long-distance communications problems unique to county and regional systems, but many difficulties remain.

Performance analysis of cache strategy for signaling traffic management in a wireless ATM network

In a wireless ATM network for mobile multimedia services, conventional signaling protocols generate heavy traffic because the signaling load must be handled in a HLR (Home Location Register). This centralized structure of the wireless ATM network causes critical connection setup delays. Thus, distributed processing based on a reduction of the connection setup delays is needed in wireless ATM networks. A cache strategy for call delivery with cache updates of registration based on ATM multicasting is introduced with a comparison of the cost of cache scheme with the cost of a conventional scheme. Results show that the cache scheme has better performance than conventional methods when portable mobility is low with large traffic density.

A parallel and distributed routing algorithm with a hierarchical connection management architecture for ATM/B-ISDN

In this paper, we propose a parallel and distributed routing algorithm for the ATM/B-ISDN transport networks. In the proposed routing algorithm, a hierarchical connection management architecture is used where each subnetwork has its own connection management functions to find the shortest path for the requested subnetwork connections and the routing information is merged by the upper-level domain subnetwork to find the shortest path in the merged domain of upper-level. This subnetwork routing is performed in each subnetwork in hierarchy, providing maximized parallel and distributed processing capability. The proposed parallel and distributed routing algorithm can reduce the routing and connection setup time in a large-scale network, such as a public B-ISDN.

On the design of secure ATM networks

Asynchronous Transfer Mode (ATM) is seen to be a technology that allows flexibility, efficiency and manageable bandwidth on demand to be achieved in high-speed networks. ATM is able to support a variety of applications including voice, video, image and data with different quality of service requirements. This paper addresses the design and implementation of security services and mechanisms in ATM networks. The paper examines the various design options for the placement of security services within the ATM protocol reference model and considers their advantages and disadvantages. The option of placing the security layer between the ATM Adaptation Layer (AAL) and the ATM layer is selected and the design of security services such as confidentiality, integrity and data origin authentication services in the user plane are described. The paper then presents an authentication scheme and key establishment protocol. This protocol is integrated with the existing ATM signaling protocols as part of the call setup procedures in the control plane. Then the paper discusses a public key infrastructure for the ATM environment and considers the design of public key management protocols between ATM nodes and Certification Authority for initializing, retrieving and distributing public key certificates. Finally, the paper considers the design of access control service for ATM networks and discusses the issues involved in the provision of access control mechanisms both at the connection setup phase and during the user data transfer phase. It seems that the developed security design can be transparently integrated to secure ATM networks.

An architecture for a wavelength-interchanging cross-connect utilizing parametric wavelength converters

This paper proposes an architecture for a wavelength-interchanging cross-connect (WIXC) that can be used as a switching node of strictly transparent and scalable networks with all-optical routing and all-optical wavelength conversion capabilities. This architecture utilizes all-optical parametric wavelength converters based on difference-frequency-generation (DFG) or four-wave mixing (FWM), although this work focuses only on the implementation using difference-frequency-generation wavelength converters. The proposed WIXC architecture exploits the unique wavelength mapping properties of parametric wavelength converters: mirror image mapping and simultaneous multichannel wavelength conversion. The derivation of this architecture involves application of a space/wavelength transformation to the classical Benes switch fabric. The connection setup for the resulting architecture follows the well established looping algorithm, and the architecture is scalable in both the ports and the wavelengths. The scaling occurs in an orderly fashion, which allows modular upgrades of WIXC's for cost-effective evolution of the networks. The unique properties of the parametric wavelength converter including transparent and multichannel conversion capabilities result in a WIXC architecture that requires fewer wavelength converters while maintaining scalability and transparency.

An Approach to Quality of Service Management in Distributed Multimedia Application: Design and an Implementation

Most work related to quality of service (QoS) is concerned with individual system components, such as the operating system or the network. However, to support distributed multimedia applications, the entire distributed system must participate in providing the guaranteed performance levels. In recognition of this, a number of QoS architectures have been proposed to provide QoS guarantees. The mechanisms and schemes proposed by those architectures are used in a rather static manner since the involved entities, e.g., the network, sender and receiver, are known before the connection (call) set-up phase. In contrast to these architectures, we propose a general QoS management framework which supports the dynamic choice of a configuration of system components to support the QoS requirements for the user of a specific application. We consider different possible system configurations and select the most appropriate one depending on the desired QoS and the available resources. In this paper we present an overview of this general frameworks especially, we concentrate on QoS negotiation and adaptation mechanisms. To show the feasibility of this approach, we designed and implemented a QoS manager for distributed multimedia presentational applications, such as news-on-demand. The negotiation and adaptation mechanisms which are supported by the QoS manager are specializations of the general framework. The proposed framework allows to improve the utilization of system resources, and thus to increase the system availability; it also allows to recover automatically, if this is possible, from QoS degradations. Furthermore, it provides the flexibility to incorporate different resource reservation schemes and scheduling policies, and to accommodate new system component technologies.

A novel congestion control mechanism for multicast real-time connections

Time framing strategies such as Stop-and-Go (S&G) [Golestani S.J., Congestion-free transmission of real-time traffic of real-time traffic in packet networks, IEEE INFOCOM, 1990, pp.527-536; Golestani S.J., A framing strategy for congestion management, IEEE JSAC, 9(7), 1991, pp.1064-1077; Golestani S.J., Congestion-free communication in high-speed packet networks, IEEE Trans. on Communications, 39(12), 1991, pp.1802-1812; Golestani S.J., A stop-and-go queueing framework for congestion management, ACM SIGCOMM, 1992, pp.8-18] and Continuous Framing (CF) [Jau-Hsiung Huang, Biau-Jwo Tsaur, Continuous framing mechanism for congestion control in broadband networks, Computer Communications, 18(10), 1995, pp.718-724] are designed to support the end-to-end delay bound and jitter bound for unicast connections. Considering the features of real-time multicast connections, a new time framing mechanism named Multicast Continuous Framing (MCF) is proposed in this article. S&G and CF allow only one time frame length per connection, but MCF allows changing of the time frame length of a connection at intermediate nodes so that the statistical multiplexing gain within a connection is increased, i.e., the bandwidth requirement can be reduced. We also present the multicast connection setup scheme for MCF in the article. Simulation results show that MCF has a much better performance than that of CF, and the tighter jitter bound a connection requests, the more performance improvement MCF can obtain.

Internetworking connectionless and connection oriented networks

The use of connection-oriented (CO) networks for the transport of IP traffic is seen to have value to both users and service providers. Given the expectation that most endpoint-generated traffic will be in the form of connectionless (CL) IP datagrams, we address the problem of how to internetwork a CL (IP) network with a CO network. CO networks can be packet-switched or circuit-switched. Examples of packet-switched CO networks include ATM and MPLS networks, in which resource reservations are made at the ATM or shim layer, and IP-switch-based networks, in which resource reservations are made at the IP layer. Examples of circuit-switched networks include SONET/SDH and WDM networks that consist of programmable optical crossconnects. We consider the internetworking problem for two modes of operation of CO networks: provisioned, in which connections are set up a priori, and switched, in which connections are set up on demand. The main focus of this article is on the more complex problem: the internetworking of CL IP networks with CO networks operated in a switched mode. Our solution consists of (i) interworking user plane protocols with protocol conversion in some cases instead of always using protocol encapsulation, (ii) interworking routing protocols by either simply having gateways know routing information of both networks or having all nodes know routing information of both networks, and (iii) interworking signaling protocols by using application- or transport-layer end-to-end handshakes to trigger connection setups through the CO network. We demonstrate throughput improvements with our integrated routing interworking scheme over the MPOA IP-ATM internetworking solution for two example networks.

Integrating Internet with PSTN networks for voice services

The potential of internet telephony circumventing long distance rates is certainly appealing as one can talk to someone on the other side of the world for as long as desired at no more than the cost of the local internet access and connectivity charges. This paper discusses an Internet Telephony Gateway that allows the delivery of voice services through the internet to conventional telephones on the Public Switched Telephone Network (PSTN). The gateway comprises a hardware interface card, and two software components for session and audio management. The hardware interface interacts with the trunk line to obtain audio data, answer, initiate and terminate a call. Additionally, it converts audio signal into a digital form suitable for transmission over the internet. The session and audio management interface with the internet for connection set-up, monitoring of the quality of services, negotiation of session parameters and audio communication.

Analysis of windowing mechanisms with infinite-state stochastic Petri nets

In this paper we present a performance evaluation of windowing mechanisms in world-wide web applications. Previously, such mechanisms have been studied by means of measurements only, however, given suitable tool support, we show that such evaluations can also be performed conveniently using infinite-state stochastic Petri nets. We briefly present this class of stochastic Petri nets as well as the approach for solving the underlying infinite-state Markov chain using matrix-geometric methods. We then present a model of the TCP slow-start congestion avoidance mechanism, subject to a (recently published) typical worldwide web workload. The model is parameterized using measurement data for a national connection and an overseas connection. Our study shows how the maximum congestion window size, the connection release timeout and the packet loss probability influence the expected number of buffered segments at the server, the connection setup rate and the connection time.