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DTM, Dynamic synchronous Transfer Mode, is a broadband network architecture based on fast circuit-switching augmented with dynamic reallocation of resources. It provides a service based on multicast, multi-rate channels with short set-up delay, and supports applications with real-time requirements on quality of service as well as applications with bursty, asynchronous traffic. This paper describes the DTM architecture and its distributed resource management scheme. Performance analysis results from network simulations are presented. The analysis is performed with respect to throughput and access delay for two network topologies: a dual bus and a grid of dual buses. The effects of varying user requirements, inter-node distance and transfer size are studied for uniform traffic patterns. The results indicate that the overhead for establishing channels is low (a few hundred microseconds), which gives a high degree of utilization even for short transfers. The analysis also shows that when channels are established very frequently, the signalling capacity limits the performance.

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IEC

Dynamic synchronous transfer mode (DTM) is an exciting networking technology. The idea behind it is to provide high-speed networking with top-quality transmissions and the ability to adapt the bandwidth to traffic variations quickly. DTM is designed to be used in integrated service networks for both distribution and one-to-one communication. It can be used directly for application-to-application communication or as a carrier for higher-layer protocols such as Internet protocol (IP).

This tutorial explores the development of DTM in light of the demand for network-transfer capacity. DTM combines the two basic technologies used to build high-capacity networksıcircuit and packet switchingıand therefore offers many advantages. It also provides several service-access solutions to city networks, enterprises, residential and small offices, content providers, video production networks, and mobile network operators.

Over the last few years, the demand for network-transfer capacity has increased at an exponential rate. The impact of the Internet; the introduction of network services such as video and multimedia that require real-time support and multicast; and the globalization of network traffic enhance the need for cost-efficient networking solutions with support for real-time traffic and for the transmission of integrated data, both audio and video. At the same time, the transmission capacity of optical fibers is today growing significantly faster than the processing capacity of computers. Traditionally, the transmission capacity of the network links has been the main bottleneck in communication systems. Most existing network techniques are therefore designed to use available link capacity as efficiently as possible with the support of large network buffers and elaborate data processing at switch points and interfaces. However, with the large amount of data-transfer capacity offered today by fiber networks, a new bottleneck problem is caused by processing and buffering at switch and access points on the network. This problem has created a need for networking protocols that are not based on computer and storage capacity at the nodes but that instead limit complex operations to minimize processing on the nodes and maximize transmission capacity

Against this background, the DTM protocol was developed. DTM is designed to increase the use of fiber's transmission capacity and to provide support for real-time broadband traffic and multicasting. It is also designed to change the distribution of resources to the network nodes dynamically, based on changes in transfer-capacity demand.

To read more of this tutorial please visit IEC's DTM Tutorial.

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Net Insight

Within ETSI an activity is underway to specify the Dynamic synchronous Transfer Mode (DTM) set of protocols for the creation of a new synchronous transport network able to carry multiple services at different data rates.

The technology originally results from work done within Ellemtel, was further developed at the Royal Institute of Technology (KTH) and has since been refined by Net Insight and Dynarc. The goal of standardisation is to bring the fruits of this development effort into the realm of ETSI standards.

The DTM technology provides dynamic channel establishment, dynamic bandwidth adjustment over isochronous channels using simple and predictable switching mechanisms while achieving high bandwidth, low arrival jitter, strict Quality of Service at a low cost. It is able to deliver a multi-service transport service with scalability into the future.

To learn more about DTM, please visit Net Insight.