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Several different types of service levels can be negotiated, including:
Designing networks to support multimedia applications involves more than just networking requirements; attention must also be paid to the entire system. Network configurations, for example, do not treat how the bandwidth is handled once it reaches the desktop. Bus speeds and I/O throughput are part of the link between the data source and the users screen. There are two possible approaches to handling bus speeds and throughput:
Bandwidth also is handled through compression techniques for images and video that radically reduce the amount of data transmitted and consequently lower bandwidth requirements. Multimedia information is bursty, meaning that some parts of it require higher bandwidth than others. Dynamic bandwidth allocation is useful to lessen the network burden.
Another consideration involves the accommodation of real-time requirements by the operating system. For example, the jitter and slowdown of a movie player may not be due to availability of resources but to a lack of proper scheduling. A music play program often picks up speed when contending programs terminate. Principal requirements for multimedia-capable operating systems are as follows:5
The extensive bandwidth and storage required to transmit multimedia streams coupled with the insufficient bandwidth of existing networks pose one of the major barriers to multimedia networking. The tendency of existing networks to treat individual streams as independent and unrelated units underscores the challenge of and need for effective synchronization.
Another major roadblock in networking existing applications is caused by proprietary development environments, data formats, and runtime environments, and by incompatible proprietary client-server models. The tight coupling among existing devices, data formats, and application program interfaces (API) makes it even more difficult to devise a standard. Heterogeneous delivery platforms pose networking challenges even when multimedia applications are not involved.
Other related concerns that aggravate existing problems associated with networked multimedia applications result from the lack of uniform standards in the following areas:
The challenge in networking applications is to develop a strategy that works with existing technology and enables management to provide gradual enhancements to the existing infrastructure. Both scalability and integration must be considered during the planning process. In terms of network management support, the technology chosen should support the entire infrastructure.
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