Information Transmission with Quality of Service

Information Transmission with Quality of Service

Manjunath Ramachandra (MSR School of Advanced Studies, Philips, India)
DOI: 10.4018/978-1-60566-888-8.ch020
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The data being transferred over the supply chain has to compete with the increasing applications around the web, throwing open the challenge of meeting the constraint of in-time data transfers with the available resources. It often leads to flooding of resources, resulting in the wastage of time and loss of data. Most of the applications around the customer require real time data transfer over the web to enable right decisions. To make it happen, stringent constraints are required to be imposed on the quality of the transfer. This chapter provides the mechanism for shaping of traffic flows towards sharing the existing infrastructure.
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In the previous chapter, the different techniques for the transfer of the information over a medium are discussed. Often, the data has to reach the end user or the application in right time as well as the real time. It puts a lot of constraints on the quality of service from the network. Here, these techniques are discussed in detail.

The present day internet is being put in to various applications falling under the umbrella of web services. It has thrown open new avenues for web based e-commerce. As an example, it has enabled online booking of flight tickets, online check-in, online clearance of electricity dues etc. In all these cases, the transactions have to happen in real time enabling the end user to interact with the databases. Though the data transfer involved is small, it has to happen in real time, without distortion in the information. It calls for stringent constraints to be imposed on the packet delay and losses. The user experience and feedback are given due importance. A mechanism where by the end users’ feedback in terms of the service quality would reach the information source is explained in this chapter. The same would be used to adjust the quality of service in the transferred data. It will have profound impact on the resource management in the network.

The quality of service in turn dictates the mode of data transfer. For example, the end user has to wait for several hours to get the next morning news paper. On the other hand, the football match has to be telecasted “live”. The interactive speech data has to avoid the satellite channel due to the latency and the cost incurred. A fax data can still use the satellite link conveniently. A twisted pair cable can not support the live video for multiple users. However, it can support file transfers. In this chapter, the different media for the data transfer are explored

Enforcement of service quality over the transfer of the information in a resource-crunched network is a tough task calling for the proposal alternative architecture and designs. One of the solutions for this problem is to classify the data packets based on the priority and discard the one with lower priority if there is a contention for the resources. Alternatively, the service guarantee may be provided on per flow basis. The quality of service (QoS) is satisfied for all packets in a flow with the appropriate reservations irrespective of the priorities of the individual packets in the end to end flow. The per class QoS architecture is simple and goes well with the internet traffic and the architecture.

The excess of one data stream in terms of the Quality of service will have a profound effect on the entire flow with multiple streams, especially when they share the common resources such as buffers. With the techniques explained here, the service parameters of the streams are held nearly constant, in spite of a few bad flows.

The focus of discussion in this chapter is on the data transfers over the contention for physical media towards meeting the service quality and the recently proposed class-based service architectures and the mechanisms to implement the same. The data transfer is involved with in the organization, internet, web services etc. In this chapter, the example of Differentiated Services architecture will be elaborated. The issues associated in the data transfers with stringent quality of service requirements are brought forward and the solutions will be proposed.

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