Improving End-System Performance with the Use of the QoS Management Marcio Andrey Teixeira1 and Jamil Salem Barbar1 FACOM - Universidade Federal de Uberlandia (UFU), Av. Joao Naves de Avila, 2121, 34800-902, Uberlandia - Brasil
[email protected],
[email protected]
Abstract. Nowadays, due to the great variety of resources and multimedia applications available in the end system, especially those related to distributed multimedia application , it is been necessary to rely on the Quality of Service management to the improvement of the performance. The present article shows how this can be possible through the use of the management protocol Simple Network Management Protocol and its primitives, by means of the use of adequate management resources and applications.
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Introduction
Due to the dynamic increase of the computational power of end systems, such as personal computers and networks, the local resource availability and the increasing use of Internet have been leading to the emergence of several distributed multimedia applications, especially the ones related to distributed multimedia applications. These applications give priority to a closer interaction between users through the massive use of multimedia resources. However, they cause a great increase in the consumption of the net and the end system, which have to be managed to guarantee minimum acceptable Quality of Service (QoS), in order to please the final user end increase the systems’ performance. The most used management protocol nowadays, especially in the monitoring of networks, is the SNMP (Simple Network Management Protocol ). Thus, this article aims at showing that the use of primitives and the MIB (Management Information Base) [1] of the SNMP will be able to be extended to the QoS management in end systems. These procedures, besides being innovative, take into consideration the advantages and the simplicity of the management protocol.
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QoS and End System
The QoS comprises some stages such as the specification, that consists of obtaining QoS requirements in the application level, the QoS management mechanisms responsible for keeping the defined QoS level and, at last, the so-called provision [2]. J.N. de Souza et al. (Eds.): ICT 2004, LNCS 3124, pp. 601–606, 2004. c Springer-Verlag Berlin Heidelberg 2004
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The end systems manipulate multimedia streams, such as audio and video streams, proceeding from the multimedia applications. Depending on the existing resources, the end systems are able to generate and show such streams with a certain level of quality, as well as send or receive them through the network. The distributed multimedia applications use multimedia resources massively; that is the reason why the intense execution of these applications leads to the scarce availability of the end system resources and a performance below of the waited one, being necessary to proceed to its management, in order to guarantee (if possible) the execution of the applications in a satisfactory way. Each multimedia application have quality of service requirements, and such requirements are referred to by QoS parameters. The QoS parameters are defined in the ISO patterns, as being the the collective effect of the performance of a certain service, which determines a service user’s satisfaction level [3]. The parameters of QoS specify the amount of resources placed for the services, as well as your discipline of use of the shared resource in one distributed application system, for example, the end-to-end delay parameters determines behavior of the transmission services to the long one of the passage of the media since the origin to the destination, with respect to the scheduling of process (allocation of bandwidth), queuing, (allocation of space), to the o scheduling of tasks (allocation of cpu processing time).
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QoS Management
The multimedia applications share the need of QoS management to guarantee the meeting of its requirements and, consequently, the keeping of a certain quality (or service) level, having always in mind the user’s satisfaction. Memory, CPU, storing Buffer, video, audio, etc. are examples of these requirements. There are some Frameworks [4] used in the QoS management that define complete sets of management mechanisms. These mechanisms must be inserted in the end system in order to manage the QoS of the multimedia applications in general, provided they are not present. In subsection 3.1 the basic QoS management mechanisms will be described. 3.1
QoS Management Mechanisms
The end system can be seen as an abstraction of several levels or layers, as observed in Fig. 1 [3]. For better agreement, the end system can be divided in three levels: user’s level, application level and system level with the audio, video and network device. There is a fourth abstraction level, which is the network level, but the present article focus only on the QoS management of the end system. This abstraction is used in the understanding of the fundamental mechanism performance in managing the QoS and is part of the proposed management, as it follows:
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User’s Level
Application Level
System Level
Audio/video Device
Network Device
Fig. 1. Representation of the QoS levels in the end system.
Mapping Mechanism: It plays the role of translating the QoS parameters among the several end system levels. The QoS parameters, arising out of the user’s level, must be mapped for the inferior levels (or layers) inside the end system because the representation of these parameters is different from layer to layer (Fig. 1). Negotiation Mechanism: It has the aim of adjusting common values between the application and the end system, defining, this way, the QoS level that will be used in the multimedia application. Admission Mechanism: It is responsible for comparing the resources resulting from the QoS parameters of the multimedia applications with the resources available in the end system. Monitoring Mechanism: It monitors the QoS attributed to a multimedia application and compares it with the expected one.
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Improving End System Performance with the Use of the QoS Management
The QoS management proposed for the end system comprises an Application Manager, a QoS Manager and a Resource Manager. Due to these managers individual traits, they can be implemented as modules. Each module has mechanisms used in the QoS management. The Application Management, QoS Management and the Resource Management modules, through a SNMP agent, use the MIB to obtain information both about the end system and the multimedia applications. The MIB has objects related to the resources and the device of the end system, like, for example, memory, CPU, buffers, process priority, number of packets leaving and entering the network interface, etc. The values of these objects represent the real state of the resources and/or device of the end system, because such values are obtained from the very operational system. The Fig. 2 shows the management modules, their respective mechanisms, the SNMP agent and the MIB.
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Application Management Monitoring
QoS Management Mapping
MIB
SNMP Agent
Negotiation Admission
Resource Management
Fig. 2. The Management modules, their mechanisms, the SNMP agent and the MIB.
The MIB provides the information required for the management modules to achieve the proposed management like, for example, the resource availability, the multimedia application requirements and the QoS parameters. The functionality of the MIB, proceeding from the SNMP is extended, therefore the referring objects to the requirements of the multimedia applications if find inserted into the MIB, as it did not have them. The MIB information is structured, for each multimedia application that will be managed, in the following way: Name of the Application to be managed, for example, video class application. The types of the medias used in this application, for example, audio and video. The QoS parameters referring to the requirements of the multimedia applications and to the QoS level intended to be guaranteed The QoS parameters are structured in the MIB according to their representation in each one of the levels in which the end system is divided, making it easier to map the QoS parameters in their respective layers. 4.1
Functioning of the Management Modules
The Fig. 3 shows the arranging of the management modules in the end system. The management modules are treated by the operational system with a further application in the system. One another possibility would be embedded in the kernel of the operational system the management modules, but this would affect referring questions of portability, not being very adjusted at the moment. Application Management Module. The application management module checks which multimedia applications need to have QoS guaranteed. This is
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Application 1 Application n
Application Management SNMP Agent
MIB
QoS Management Resource Management
Operation System
CPU
Memory
Bus
Audio
Video
Fig. 3. Management modules in the end system.
achieved through the use of a deamon acting as a command interpreter (Shell) that compares the multimedia application to the entries of a chart resident in the MIB (by using a SNMP agent). Once the checked multimedia application needs checked QoS guarantee, the application management obtains its QoS requirements which were predefined in the MIB and send them to the QoS management module. QoS Management Module. The QoS Management Module is responsible for doing the mapping (or translation) of the requirements of the multimedia applications in QoS parameters, in the representation of the levels (or layers) in which the end system was divided as well as the admission test. Through the SNMP agent, the QoS management module access the MIB to map the QoS parameters, obtaining this way the necessary resources to the execution of a multimedia application. After the mapping, a negotiation of these QoS parameters takes place in the end system. The QoS manager checks whether the end system will be able to execute the multimedia application with the initial parameters which represent a certain level of quality. In case the result is positive, the QoS manager will send this information to the resource manager, because the resources will be available and will be able to be allocated; later, the QoS manager will send a notification to the application manager along with the negotiated parameters, accomplishing the admission test. Resource Management Module. The Resource Management Module uses values of the MIB objects to book the resources, for example: an object that represents the quantity of Buffer that will be used by a certain application. When
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the value of this object content is altered, the resource manager will allocate the specified room in the object. Through the Resource Manager, it is also possible to increase or decrease the priority of certain applications, define he quality of an image that will be introduced to the user, with the changing of its QoS parameters or the resolution of the user’s screen. For each allocated resource, the resource management module will proceed to the accounting of the end system resources and will update, in the MIB, the remaining values in the current resources, in order to have a new negotiation of the resources later, having in mind other applications. The same fact takes place when a resource is released.
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Conclusion
With this management, a time that the resources are managed in function of the demanded requirements, the end system will be able to offer QoS guaranteed for the multimedia applications, then, to improve the performance of these applications. The present QoS management is proposed to meet the needs of the current lack of QoS management in the end system, as most papers are concerned with the network service, offering the multimedia applications a fairer sharing of its resources due to the use of multimedia resources. The management with the use of the MIB and the SNMP protocol, as it was described above, allows the multimedia applications in the end system to be remotely managed, with the required safety criteria, according to the needs imposed by these applications. Thus, it makes possible the emergence of new multimedia distributed applications. For instance, in video class applications, Tele medicine and Video on Demand, each user will remotely be able to select different QoS parameters (image resolution, view angle, etc.).
References [1] Stallings, W.: SNMP, SNMPv1, SNMPv2, SNMPv3, and RMON 1 and 2. AddisonWesley Longman, Inc., 1999. (Third Edition). [2] Oliveira, F.P., Ferras, C.A.G.: Um Modelo de Qualidade de Servi¸co para Aplica¸co ˜es de Educa¸ca ˜o a Distˆ ancia[OnLine]. Available: http://lsm.dei.uc.pt/ribie Laste acces: 04/02/04 [3] Nahrstedt, K., Steinmetz R.: Resource Management Networked Multimedia Systems. IEEE Computer Magazine, v.28, n. 5, (1995) 52-63 [4] Aurrecoechea, C., Campbell, A. T., Hauw, L.: A Survey of QoS Architectures.[Online]. Available: http://comet.ctr.columbia.edu/ campbell/papers/multimediaa.pdf Last acess: 15/01/04
