ISSN:1124-318X    

DOI:10.1002/ett.4460070502

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractSeveral articles in this special issue of the ETT journal, entitled “ATM Field Trials and Experiments”, refer to specific traffic experiments performed on the “EXPLOIT” ATM testbed in Basel, Switzerland. This paper is intended to give the reader a general introduction to this testbed, background information about the project in which it has been supported and extended, and an in; sight into the range of areas in which traffic experiments have been performed. The testbed currently comprises 6 ATM switches, interworking capabilities toN‐ISDN and Frame Relay, broadband signalling and traffic control features which, combined with access to the European ATM network, form a unique platform for the testing of new broadband terminals and applications. Sophisticated traffic generation and analysis equipment is also being used to undertake traffic experiments, mainly in the ATM‐sensitive areas of traffic control, resource management and network

ISSN:1124-318X    

DOI:10.1002/ett.4460070503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractThis paper deals with the experimental investigation of a preventive traffic control framework for ATM networks as implemented in the EXPLOIT Testbed. This framework comprises a Usage Parameter Control (UPC) function and a Connection Admission Control (CAC) function. The obtained measurement results are complemented and compared with simulation studies and analytical results. For several On/Off traffic types it is shown that the implemented UPC function enforces both the Peak Cell Rate (PCR) and the Sustainable Cell Rate (SCR) simultaneously. By measuring the cell loss ratio as a function of the number of multiplexed sources, admission boundaries for a given network performance objective can be found and compared with the implemented CAC function based on the convolution algorithm. It appears that network performance objectives can be guaranteed, while exploiting most of the possible multiplexing gain in a network with small buffers like the EXPLOIT Testbed. Finally, it is shown that the two co‐operating functions constitute a traffic control framework which is robust against traffic contract violations as well as worst case traffic utilising the contracted UPC function tolerances maximally at both the cell level and the burst leve

ISSN:1124-318X    

DOI:10.1002/ett.4460070504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractMeasurements of theCDVthat aCBRconnection accumulates through an ATM network that consists of several switches are presented in this paper. Combining network segments on the EXPLOIT testbed, the Swiss ATM pilot network and the ATM Local Area Network at the Swiss Federal Institute of Technology, an extended test platform could be constructed to evaluate the magnitude ofCDVaccumulated in a real network. The measurement results are compared to simple tractable models that can be used to dimension theCDVtolerance for UPC/NPC functions along the network. Finally, an estimation of the impact ofCDVon resource allocation is carried out using so‐called Worst Case Traffic models to estimate the maximum amount ofCDVtolerated to guarantee the proper operation of multiplexing function

ISSN:1124-318X    

DOI:10.1002/ett.4460070505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractA number of experiments were designed and performed on the EXPLOIT ATM testbed, aiming at validating selected results on statistical multiplexing of bursty traffic. The influence of the burst‐size and silence‐duration distributions on the multiplexer's performance, the performance experienced by the individual classes in a heterogeneous traffic environment and the performance in the case of heterogeneous traffic featuring different time scales are the main issues investiga

ISSN:1124-318X    

DOI:10.1002/ett.4460070506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractThe RACE project TRIBUNE is focused on a number of issues pertaining to the introduction of the Integrated Broadband Communication. The project has implemented a broadband test‐bed with a fully standardized Broadband User Network Interface (B‐UNI) according to the latest ITU‐T recommendations. A lot of effort was therefore spent on the specification, implementation and verification of theB‐UNI and the integration of the test‐bed. This paper is intended to focus on the evaluation of the innovative methods used and experience gained during the three year period of specification, implementation and verification. In this paper we will start with focusing on the specification of the B‐UNI. Particularly the decision to use formal specification languages (‐SDL 88) will be evaluated. The actual implementation of theB‐UNI is discussed in the second part, specially the experience and result of the use of automatic code generation modules. We will elaborate on how the verification of the implementation of theB‐UNI was managed in the third part of this document. Specially the use of the Ferry Clip method and the automatic generation of test suites will be focused upon. Finally, we will show that the taken steps in the previous phases have led to relatively short and easy integration phase of a complex test

ISSN:1124-318X    

DOI:10.1002/ett.4460070507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractWe present and discuss measurements performed with XTPX over the European ATM Pilot. The main characteristic of this wide area ATM network is that the traffic contract is enforced by a Usage Parameter Control (UPC) mechanism. When the ATM traffic is compliant with the traffic contract, XTPX achieves a good utilisation of the link. However, when the ATM traffic is not entirely compliant, the UPC discards cells and the link utilisation becomes very low.

ISSN:1124-318X    

DOI:10.1002/ett.4460070508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractFrom mid‐94 to end‐95 the“Performance Working Group (PWG)”of theATM PILOThas carried out a lot of measurements (in relationship to functions available on test equipments). The results obtained were mainly related to ATM layer performance measurements (availability and non time‐related performance parameters) and to traffic characterization. Performance measurements aimed at checking the validity of the set of proposed or standardized ATM layer performance parameters, at studying the sensitivity of the parameters definitions and at obtaining early results in order to propose performance objectives for the relevant recommendations. These results have shown that the ATM layer performance is very much dependent of the observation period of time and of the physical path of the connection under test. Furthermore it has been observed that the ATM layer performance is not so sensitive to the parameter definitions and the associated thresholds. Traffic characterisation is necessary to identify what is going on in the network (will the cells be equally spaced or will they come in bursts ?). The PWG had taken the opportunity to do field trials with real traffic coming from Pilot and has carried out a range of tests on bothCBRsources (carrying voice or video applications) andVBRsources (multimedia application or LAN to LAN interconnection). Two main traffic types have been observed during the tests:CBRsources carrying voice or video applications.VBRsources with multimedia applications or LAN to LAN interconnection using the SMDS/‐C

ISSN:1124-318X    

DOI:10.1002/ett.4460070509

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractIn this paper, we report on how System V UNIX scheduling can affect the way a workstation outputs ATM cell traffic under various process loads. Whenever multiple processes run concurrently, process contention occurs that creates burstiness and affects a workstation's traffic output. Experiments using a generic sending process and an FTP file transfer were performed that reveal the scheduling contention effects on traffic flow. Our results show that contention can introduce significant cell delay which can be on the order of hundreds of milliseconds. In addition, burstiness occurs where cells are “clumped” together in a variable manner. The average cell output rate decreases with increasing process load, but there is a preference given to a process that transmits cells as opposed to CPU‐intensive programs. The impact of scheduling on traffic shaping based on aleaky bucketis also examined. We show that improper selection of the shaping parameters can occur if change in the process load is ignored and if the initialtransientassociated with process start‐up is not accounted for. Lastly, we make some comparisons between the scheduling algorithms of System V and 4.3 B

ISSN:1124-318X    

DOI:10.1002/ett.4460070510

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460070511

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY