Connection Setup Research Articles

Minimum buffer size for overflow avoidance in ATM CBR/VBR connection multiplexing

Connection admission control (CAC) functions in asynchronous transfer mode (ATM) networks require that a traffic descriptor (TD) be specified at connection setup. Existing standards define rule based traffic parameters, from which worst-case proof bounds for cell arrivals of a compliant connection can be derived. The purpose of this letter is to establish the minimum amount of buffer space actually required to avoid buffer overflow in a multiplexer loaded by constant bit rate (CBR) and variable bit rate (VBR) connections, meaning that any smaller buffer can be overflowed with positive probability. The relevance of this result is to provide a definite benchmark for possible resource savings assessment of statistical multiplexing schemes.

An integrated call admission and buffer management scheme for LAN interconnection over a shared-memory ATM switch

We consider the problem of interconnecting low speed LANs over a high-speed shared-memory ATM switch. A bottleneck is formed when more than one source originate traffic to the same destination LAN. In this case, a congestion may be created at the output gateway (destination LAN interface) and the required services are interrupted. In this paper we propose a new integrated scheme for call admission (CAC) and buffer management. The objective of the scheme is to prevent the congestion at the destination LANs, as well as within the ATM switch, while minimizing connection rejection rates (maximizing the utilization of the ATM switch). The scheme uses two types of parameters: first, the connection parameters which are estimated at the network interface unit and specified during connection set-up, and second, the actual traffic characteristics and buffer requirements. Therefore, the proposed scheme combines both parameter-based and measurement-based approaches to the problems of call admission and congestion control. The proposed scheme is shown not to require intensive computations and can be implemented in real time in a high-speed ATM switch. A simulation model for the system is developed from which the performance of our integrated CAC and buffer management scheme is evaluated. It is shown that the application of our CAC criteria maintains cell/packet dropping to within the same order of magnitude. It is also shown that using virtual buffer allocation, in conjunction with our CAC criteria, results in almost no cell/packet dropping.

Flowmeter for QoS provision in packet switched networks

A flowmeter is a set of traffic-related variables associated with a connection established in a network node as a result of the connection setup. Comprehensive quality-of-service provision to each packet flow is the purpose of flowmeter-based dynamic packet scheduling. The earliest deadline first (EDF) scheduling algorithm is adopted for rate allocation, delay control, and flow control. A gas pressure admission control algorithm is also presented to simplify EDF admission test. The delay performance of the scheduler is evaluated on a subnetwork of the Internet.

A route optimization algorithm and its application to mobile location management in ATM networks

In this paper, we propose an algorithm for optimizing the route of a connection that becomes suboptimal due to operations such as handoffs and location-based reroutes, for mobile ATM (asynchronous transfer mode) networks based on the PNNI (private network-to-network interface) standard. This algorithm uses hierarchical route information of the connection and summarized topology and loading information of the network to determine a such that adjusting the connection from that crossover node results in an optimally routed connection. We then apply this algorithm to the mobile location management problem. Location management schemes have been proposed in which an incoming call to a mobile is routed to its home switch (based on summarized reachability data) and then rerouted to the mobile's current location. If we consider such rerouting a first phase of mobile connection setup, a second phase is required to optimize the paths of such rerouted connections. Such an approach is considered a two-phase mobile location/connection setup scheme. Alternatively, an incoming call to a mobile can be routed to its home switch based on summarized reachability data, and then cranked back to an optimal crossover node before rerouting the connection to the mobile's current location. Such a scheme is a one-phase mobile location/connection setup scheme since it directly results in an optimal path. A comparative performance analysis of the one- and two-phase connection setup schemes is presented. Measures of comparison are call setup delay and the amount of network resources allocated to a connection. The maximum call setup delay (worst case call setup delay) is lower in the two-phase scheme, but the average call setup delay is lower in the one-phase scheme. The amount of resources required for a connection in the two-phase scheme (prior to route optimization) is significantly greater than that in the one-phase scheme.

Wide-sense nonblocking Banyan-type switching systems based on directional couplers

Directional couplers are capable of switching signals with multiple wavelengths. They are the ideal technology for building light-path switches to configure wavelength division multiplexing (WDM) transmission facilities. This technology, however, has a major constraint: crosstalk. Design of a strictly nonblocking directional coupler-based photonic switching system under a specified crosstalk constraint has previously been studied. The results indicate that a lower level of crosstalk can be achieved at a cost of some extra amount of hardware. In this paper, we show that if a simple rule is followed in setting up the connections, both the amount of hardware for nonblocking networks and the connection setup time can be greatly reduced. The resulting networks thus belong to the class of wide-sense nonblocking networks.

The TINA Consortium

The Telecommunication Information Networking Architecture Consortium, established in 1993, has delivered architectural guidelines and sets of specifications for a common and coherent software architecture to enable the provisioning of telecommunications and information services. The article gives an overview of the structure and achievements of TINA-C so far and outlines future work items. The main concepts summarized in this article include business modeling, sessions, computing framework, distributed processing environment, service architecture, and network resource information modeling. Interworking concepts and migration strategy from existing technologies toward TINA and a short description of validation activities are delineated. The scope of the TINA-C initiative-including the provisioning of multimedia services, allowing flexibility in combining any kind of connectivity, third-party connection setup, and broadcasting, as well as multiparty involvement-can be seen as a most valuable complement to the global information infrastructure activities, providing an architectural underpinning for the global information infrastructure.

The estimation of signaling delay in ATM networks

In multimedia applications over ATM networks, more stringent quality of services are required, because these applications are especially sensitive to the time delay. In this letter, a simple estimation of signaling delay is presented using Erlang service models according to ITU-T "Q.2931". Additionally, the call blocking probability of a realistic network is considered. The simulation results show that the proposed model can be an effective tool to estimate the setup delay. If the connection setup delay can be effectively estimated according to the network load, then the users may decide whether or not to join this congested network, and thus contributes to the load balance of ATM networks.

A flow-based approach to datagram security

Datagram services provide a simple, flexible, robust, and scalable communication abstraction; their usefulness has been well demonstrated by the success of IP, UDP, and RPC. Yet, the overwhelming majority of network security protocols that have been proposed are geared towards connection-oriented communications. The few that do cater to datagram communications tend to either rely on long term host-pair keying or impose a session-oriented (i.e., requiring connection setup) semantics.Separately, the concept of flows has received a great deal of attention recently, especially in the context of routing and QoS. A flow characterizes a sequence of datagrams sharing some pre-defined attributes. In this paper, we advocate the use of flows as a basis for structuring secure datagram communications. We support this by proposing a novel protocol for datagram security based on flows. Our protocol achieves zero-message keying, thus preserving the connectionless nature of datagram, and makes use of soft state, thus providing the per-packet processing efficiency of session-oriented schemes. We have implemented an instantiation for IP in the 4.4BSD kernel, and we provide a description of our implementation along with performance results.

Supporting personal mobility for nomadic computing over the internet

This paper presents a new paradigm for nomadic computing over the Internet called universal personal computing (UPC), where mobile users can access computing resources, network services, and personalized computing environments anywhere using any available terminals. The concept of UPC and system design issues are discussed, and the required system architecture capable of managing different mobile objects, i.e., users and terminals, in the UPC environment is presented. Modifications of connection setup procedures between user application programs to enable addressing based on a global user identity are considered.

Mobility management in wireless ATM networks

Mobile ATM offers a common wired network infrastructure to support mobility of wireless terminals, independent of the wireless access protocol. In addition, it allows seamless migration to future wireless broadband services, such as wireless ATM, by enabling mobility of end-to-end ATM connections. In spite of the diversity in mobile networking technologies (e.g., cellular telephony, mobile-IP, packet data services, PCS), all of them require two fundamental mechanisms: location management and handoff. This article describes different schemes for augmenting a wired ATM network to support location management of mobile terminals and handoff protocols for rerouting a connection data path when the endpoint moves. A prototype implementation of mobile ATM integrating mobility support with ATM signaling and connection setup, is presented. It shows how mobile ATM may be used to provide mobility support to an IP terminal using non-ATM wireless access.

Integration of synchronous and asynchronous traffic on the MetaRing and its performance study

The main motivation for developing the MetaRing architecture was to increase the throughput of a ring-based local area network beyond its single link capacity by means of spatial bandwidth reuse. We describe and evaluate a protocol for integrating two types of traffic on the MetaRing architecture. Synchronous (reserved or real-time) traffic which is periodic and requires a connection set-up and will have guaranteed bandwidth and bounded delay, and asynchronous or bursty traffic with no real-time constraints that can use the remainder of the bandwidth in a fair manner. The integration mechanism is functionally equivalent to the timed-token function in FDDI, which is a shared media ring protocol. Simulation results are also presented to show the effects of the fairness and flow control signals on the performance of the network.

Protocol architecture for universal personal computing

This paper presents a new paradigm for network computing over the Internet called universal personal computing, where mobile users can access computing resources, network services, and personalized computing environments anywhere using any available terminals. The user and system requirements are defined, and an agent-based protocol architecture required to manage different mobile objects, i.e., users and terminals, in this computing environment is presented. Modifications of connection setup procedures between user application programs to enable addressing based on a global user identity are considered. The use of personal agents to facilitate interworking and management functions is proposed.

A pricing mechanism for scalable video delivery

Many video applications tolerate continuous media (CM) scaling. Scaling is acceptable due to human tolerance to degradation in picture quality, frame loss, and end-to-end delay. CM scaling enables the network to utilize its resources efficiently for supporting additional customers and to increase its revenue. However, due to quality degradation, users will not be willing to tolerate scaling unless it is coupled with monetary or availability incentives. We propose a pricing policy and a corresponding admission control scheme for scalable video applications. The pricing policy is two-tiered, based on a connection set-up component and a scalable component. Connections that are more scalable are charged less, but are more liable to be degraded. The proposed policy trades off performance degradation with monetary incentives to improve user benefit and network revenue and to decrease the blocking probability of connection requests. We demonstrate by means of simulation that this policy encourages users to specify the scalability of an application to the network.

A parametric wavelength interchanging cross-connect (WIXC) architecture

This letter presents an architecture for a wavelength interchanging cross-connect (WIXC) using parametric wavelength converters. The architecture exploits the unique properties of the difference frequency generating (DFG) parametric wavelength converter, including its transparency to signal format and its ability to convert multiple wavelengths simultaneously, The WIXC is shown to be scalable and rearrangeably nonblocking. Furthermore, connection setup is performed by the well-known looping algorithm used for Benes networks.

Comments on "Minimum-latency transport protocols with modulo-N incarnation numbers"

The authors comment on a class of minimum-latency transport protocols that have been analyzed by Shankar and Lee (see ibid., vol.3, no.3, p.255, 1995). The protocols use unique incarnation numbers and caching schemes to reduce the latency of connection setup whenever possible. They discuss three modifications to the protocol. (1) A modification to the opening procedure which eliminates some constraints for the correctness of the protocol. (2) A modification which allows data messages in the opening state of the client to be sent. This reduces the latency in some situations for the price of stricter constraints for correctness. (3) An alternate way of closing connections. Apart from these modifications, they also show that the proofs can be refined to get somewhat less restrictive constraints for the correctness of the protocol.

MULTICAST ROUTING SCHEMES IN ATM

In this study, we investigate the problem of accommodating multicast traffic in ATM networks, with emphasis on the virtual path (VP) environment. We propose a network structure called “virtual copy network” that is suitable for multicast communication and connection setup scheme, taking into account the VP environment. With our technique, we can expect statistical multiplexing gain in accommodating multiple multicast traffic streams over a VP. Also, we propose two multicast routing algorithms (the CNR-LH algorithm and the improved CNR-LH algorithm) for an ATM network environment. In these algorithms, in addition to determining an adequate route, the exact corresponding VPs on the route are also obtained. We examine the efficiency of the algorithms by demonstrating their basic characteristics using computer simulations.

MULTICAST ROUTING SCHEMES IN ATM

In this study, we investigate the problem of accommodating multicast traffic in ATM networks, with emphasis on the virtual path (VP) environment. We propose a network structure called “virtual copy network” that is suitable for multicast communication and connection setup scheme, taking into account the VP environment. With our technique, we can expect statistical multiplexing gain in accommodating multiple multicast traffic streams over a VP. Also, we propose two multicast routing algorithms (the CNR-LH algorithm and the improved CNR-LH algorithm) for an ATM network environment. In these algorithms, in addition to determining an adequate route, the exact corresponding VPs on the route are also obtained. We examine the efficiency of the algorithms by demonstrating their basic characteristics using computer simulations.

Achieving multimedia synchronization between live video and live audio streams using QoS controls

Recent developments of high-speed networking technologies and transmission media make it feasible to have diverse multimedia applications over integrated service networks. In order to guarantee Quality Of Presentation (QOP) to users, it is necessary to negotiate QOP parameters at the networking connection setup time, and it is also necessary to maintain service qualities during the time of presenting multimedia information. In this paper, we propose using a multimedia synchronization method for supporting smooth presentation of live multimedia information in ATM-based networking environments. The mathematic relationships among the buffer size, the maximum jitter, the presentation and transmission rates, the maximum intra- and inter-media asynchrony anomalies, etc., are presented in detail. We perform a bounded buffer allocation scheme, and forward synchronization policies for synchronizing live video and live audio streams. Since the transmission rate of live media cannot be adjusted, we perform the forward synchronization policies to overcome the asynchrony anomalies. The presentation processes at the receiver site monitor the presentation asynchrony anomalies. Once the anomalies of presentation are detected, the forward re-synchronization policy is triggered to eliminate the asynchrony anomalies. Neither a global clock nor a feedback mechanism is needed using our method.

Real-time admission control algorithms with delay and loss guarantees in ATM networks

A multimedia ATM network is shared by media streams with different performance requirements. For media streams such as file transfer, the preservation of bursts and the provision of guarantees for loss probability at the burst level is of primary importance, while for media streams such as voice, loss guarantees at the cell level are sufficient. Continuous media have stringent delay jitter requirements. Finally, some applications require loss-free transmission. In this paper a complete traffic management scheme for multimedia ATM networks is introduced. At the connection setup time, the user can choose between a loss-free connection, or a connection with loss probability guarantees, either at the cell level or at the burst level. Independent of the kind of service chosen, the network also provides strict delay jitter guarantees. A connection admission control algorithm is developed for the proposed scheme. The algorithm takes into account the statistical multiplexing of the sources and focuses on scalability with the number of sources and real-time execution (few milliseconds even for thousands of sources).

Resource management with virtual paths in ATM networks

A virtual path connection (VPC) is a labelled path which can be used to transport a bundle of virtual channel connections (VCCs) and to manage the resources used by these connections. The virtual network is organized as a collection of VPCs which form a VPC, or logical, overlay network. If the VPCs are permanent or semi-permanent and have reserved capacity, establishing new VCCs requires simple connection admission decisions at the VPC terminators of existing VPCs. This would enable faster connection establishment since transit nodes are not involved in the connection setup. The virtual path concept also allows the possibility of segregating traffic types according to quality of service requirements. However, the extent to which VPC provisioning is able to improve network efficiency is dependent on the resource management decisions that determine the VPC topology and capacity allocations. The article surveys resource management using virtual paths in an ATM network. Of interest are techniques which modify the VPC topology and capacity assignments in order to adapt to changing traffic conditions and possible network failures. The resource management activities employed to facilitate such adaptation can be categorized by the timescale on which they operate. On the shortest timescale are strategies for dynamically making minor changes to the VPC topology or capacity assignments. On a somewhat longer timescale are strategies for making more widespread modifications to the VPC overlay network. This would be appropriate for traffic changes based on time of day and for recovering from network failures. Finally, on an even longer timescale, strategies may be employed to design a general VPC overlay network, to be used at startup or after major network upgrades. Solutions to VPC resource management for each of these timescales are discussed.