Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1999-07-14
2002-11-19
Vincent, David (Department: 2732)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S395430
Reexamination Certificate
active
06483842
ABSTRACT:
This invention relates to a system and method for transporting and switching multimedia digital communications traffic carried in asynchronous transfer mode (ATM) cells.
BACKGROUND OF THE INVENTION
A recent development in telecommunications technology has been the introduction of a number of new services such as video and data services. An increasing number of subscribers is receiving sets of such services as a multimedia package. It will be appreciated that the various services have respective different formats thus introducing the problem of defining a suitable transport mechanism for delivery of these services to the subscriber. This problem has been addressed by packetising the services into ATM cells that are routed by decoding information provided in the cell headers. For interactive multimedia communication to be of value to an operator it is necessary to find some way in which the user can be charged or billed for participation in the communication in a way which is robust in terms of the accuracy of the billing records and reflects his actual use of the network. The IP real-time protocols are however not suitable for this purpose as they are best effort only and, additionally, they represent just a small component of a typical multimedia communication session.
A method of transporting multimedia traffic over a digital packet switching network is described in specification No EP-A1-0,786,919. A method of implementation of ATM adaptation layer functions is described in specification No EP-A2-0,720,410. A description of ATM networks for narrow band connections is given in specification No WO-95/17789. Reference is also directed to the ITU H.323 set of multimedia conferencing standards.
The above described incompatibility between the two types of traffic arises primarily from the different nature of IP traffic and conventional voice traffic. Voice traffic is connection oriented in that there is a requirement for the setting up of a virtual channel to establish a voice call and billing for this channel can be readily determined. IP traffic on the other hand is connectionless in nature and comprises a series of information packets each having a destination address. It is not uncommon for packets destined for the same address to reach that address via different routes. This makes billing for these services a difficult and uncertain operation. Further, the increasing number of these services has exacerbated the problem of appropriate billing to ensure that each service provider is credited with the respective service use.
SUMMARY OF THE INVENTION
An object of the invention is to provide an improved apparatus and method for providing multimedia services to telecommunications subscribers.
A further object of the invention is to provide an effective method of billing IP traffic in a connection oriented network
According to one aspect of the invention there is provided a communications network arranged to provide multimedia switched services comprising a set of minichannel media components, wherein said set of minichannel media components is encapsulated in an ATM virtual circuit and is switched as an entity so as to provide connection records for usage based tariffing purposes, wherein the minichannel components carry IP protocols and are switched using IP cut-through routing applied at the adaptation switching layer.
In a preferred embodiment, the minichannel components carrying IP protocols are switched using IP cut-through routing techniques such as the ATM Forum Multi-protocol over ATM (MPOA) applied at the AAL-2 Adaptation Switching layer.
According to another aspect of the invention there is provided a multilayer switching network having three layers, an ATM Core layer, an ATM Virtual LAN layer and an ATM adaptation switching layer to provide multimedia services to a user community.
According to a further aspect of the invention there is provided a method of delivering multimedia switched services to subscribers in a network, the method including encapsulating a set of minichannel media components in an ATM virtual circuit, and-switching the encapsulated set of media components as an entity so as to provide connection records for usage based tariffing purposes, wherein the minichannel components carry IP protocols and are switched using IP cut-through routing applied at the adaptation switching layer.
The user community may either be located on large campus sites with ATM virtual LAN switches or in small offices or home offices that are too small for such switches.
Advantageously, users may combine directly connected media sessions with known Quality of Service together with Internet media sessions with best effort QOS.
Preferably, services are based on the ITU H.323 set of multimedia conferencing standards.
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Lee Mann Smith McWilliams Sweeney & Ohlson
Nortel Networks Limited
Vincent David
Wilson Robert W.
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