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Discovering the Secrets of ATM Networks

Cociglio, Mauro; Cole, Robert


Keyword(s): ATM; telecoms management

Abstract: In the last three years, ATM networks have gone from an experimental, pilot phase to a commercial phase. All the world's major telecoms operators have completed or are completing networks which use this technology at various levels. Many different choices have been made: there are those who use ATM essentially at the trunk level and those who intend to take it all the way to the desktop. However, these networks currently lack any system able to provide full, continuous and reliable monitoring of their Quality of Service (QoS). All the more so since pure ATM networks are not at all common; most networks are mixed, comprising multiple technologies and services. Currently, various kinds of monitoring policies are enacted, and oftentimes they are not fully integrated. Information from a management center, which today is sure to be incomplete, is used; artificial traffic is generated over paths that are parallel to the user's, and their performance is assessed. Essentially, the physical layer is monitored (it certainly is the one where the most settled techniques and the most economical tools are available), assuming that if it is operating properly, then the upper layers should be operating as well. The attempt is made to integrate these methods, all necessarily incomplete, with access-side monitoring, using RMON (Remote MONitoring) for LAN users, X.25 and Frame Relay instrumentation, etc. The problem, however, is then to correlate all these different sources of information to have a full and up to date view of the QoS provided by the network. This was the starting point for the collaboration between CSELT and Hewlett-Packard Labs Bristol, aimed at specifying and developing a monitoring system for ATM networks. The goal would be to merge QoS information for the many services which in commercial networks, as we have seen, make use of ATM technology. From the CSELT side, we have drawn on the experience derived both from participating in standard-setting bodies and from our daily work supporting Telecom Italia's network in all the stages of development. For it's part, Hewlett-Packard has made available its knowledge in the fields of measurement and management of telecoms systems. This paper presents the first fruits of our collaboration. After discussing the general problem of monitoring ATM networks, we shall present the system realized by Hewlett-Packard and the applications specified and developed in collaboration with CSELT. We will then look at the issues of testing and tuning the measurement system applied first in CSELT laboratories and then to the commercial ATM network connecting two of CSELT's facilities in Turin. Lastly, we shall examine the issues involved with the commercial use of the system and prospects for evolution in the short and medium term.

9 Pages

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