Telephonic communications – Plural exchange network or interconnection – With interexchange network routing
Reexamination Certificate
1999-06-08
2002-09-10
Smith, Craigton (Department: 2742)
Telephonic communications
Plural exchange network or interconnection
With interexchange network routing
C379S219000, C379S114020, C370S238000, C370S904000
Reexamination Certificate
active
06449354
ABSTRACT:
BACKGROUND TO THE INVENTION
This invention relates, in general, to a method of configuring a system and a method of establishing a connection in such a system. More particularly, but not exclusively, the present invention relates to a communication system that utilises object-orientated code to construct a routing matrix used to establish a connection in a telephony system, such as a mixed broadband-narrowband network.
SUMMARY OF THE PRIOR ART
Telecommunication networks comprise nodes interconnected by communication resources (usually termed “links”), with a particular network technology characterised by the means of transmission of user and control information along these links and also by the routing and relaying functions embodied in the nodes. A connection from a calling party to a called party is actually achieved through an appropriate selection of a communication path, which path is determined on the basis of several decisions made by routing logic contained within switch fabrics of a network (or interconnected system of networks).
A typical switch fabric logically contains a controller (sometimes referred to as computing module or call server) that interfaces directly with a master database of network management information generally pertaining to network topology (and more especially control information). The controller is further responsible for overseeing specific call connections (e.g. trunk to trunk connections) that are managed by lower level intelligent trunking peripherals. Each lower level intelligent device functions to provide a termination for trunks (or equivalent forms of channel resource) and includes a routing function, typically in the form of an algorithm. In other words, the controller manages intelligent peripherals within the switch fabric and invokes feature codes and oversees the set-up of circuit-to-circuit (in a narrowband sense) and circuit-to-virtual path connections across a broadband interface, whereas the router function identifies a path down which control information from the controller is sent to an addressed unit. This form of distributed architecture is preferred by virtual of its flexibility, increased handling capacity over a stand-alone routing unit and its ease of upgrade, although the controller does have a limited processing capability and can only support a limited number of peripheral entities and connections.
Routing information from the controller is down-loaded to the intelligent peripherals, with the download occurring in chunks of data that are assembled at the intelligent peripheral to form a complete understanding of its available connection topology. Download can occur in response to network adaptation, such as the addition of new hardware or connection paths, but in any event is generally triggered at installation. More particularly, information download to the intelligent peripherals is presently accomplished in a multi-stage, piecewise process in which each class is assembled from the separate receipt of configuration information and availability information pertaining to confirmation of the actual physical existence of the class. In other words, in order to construct a valid object, the intelligent peripheral must receive a full complement of configuration messages; these being sent over a period of time in at least two separate bits from the controller. The configuration messages can arrive in any order.
By way of further clarification, it will be appreciated that a specific route set, a specific link set and a specific link are, in fact, all objects and that an object is therefore a combination of a set of data and a set of behaviour. Moreover, “behaviour” explains the interaction of data and thus allows the setting up of relationships through the issuance, for example, of commands or questions. Any response is therefore specific to a particular activity involved in setting up a call. Finally, to expound the relation between objects and class, it will be understood that shared behaviour between objects in endemic of the same class of objects. Each object is uniquely identifiable.
In the context of this description, it will be understood that the switch fabric is an integral part of the control network associated with each trunk, and so the term trunk implies the co-existence of an associated signalling link.
The term routing is used to describe the process of determining the path the information will take through the network, while relaying is the process of transferring information from one link to another, i.e. the information is merely passed, without alteration, from one channel resource to another.
As regards connection paths within a network, nodes (i.e. switch fabrics) are generally interconnected either by a direct communication resource or via at least one other node. Putting this another way, a trunk that is incident to a first node will be connected by the intelligent peripheral in the first node to one of a number of possible links that is believed to connect to an exit node associated with the called party. From an information perspective, each node (and particularly each intelligent peripheral by virtue of download from the switch fabric controller) is aware of certain classes of information, namely: i) route sets associated with destination nodes (e.g. switch fabrics respectively associated with Glasgow, New York and Amsterdam); ii) link sets identifying possible connection paths to the destination node; and iii) links that are connection specific. A link set will usually contain many links, whereas a route set will contain at least one link set identity together with an associated “cost” (or weighting factor) indicating a ranking preference for selection of a particular link set. As regards the “cost”, a direct point-to-point connection from an incident switch fabric to a destination switch fabric is likely to have a preferable cost as opposed to an indirect route via an intermediate switch fabric.
From an actual connection perspective, the intelligent peripheral reacts to an incoming call establishment request by finding the route set object of the destination address (which is typically derived by the dialled digits entered by the calling party). The intelligent peripheral then looks in the route set object for link sets before identifying the link set (usually) having the cheapest cost. The intelligent peripheral checks for the availability of the selected link set and then finally chooses a specific link therefrom. Information can then be sent. Basically, the various layers of selection provide robustness in routing; the process is generally known as message transfer part (MTP) routing and is part of the Common Channel Signalling No. 7 (CCS-7) protocol.
In relation to an exemplary narrowband digital network, user and control information (generally termed “data”) may be interleaved, using time division multiplexing (TDM), on a pulse code modulated (PCM) bearer channel. Data is then relayed across a node by some form of synchronous TDM switching fabric, often of the ‘time-space-time’ type. Control information (e.g. call set up and tear down messages) logically follows the same path (although not always the same physical path) through the network as user information, and is terminated in each node for routing purposes. Routing is conventionally performed, in each node, on a ‘hop-by-hop’ basis using long lived routing tables, i.e. the node is sufficiently intelligent to determine an optimum route for the succeeding network connection.
Control information is regulated by a signalling scheme that is distinctive to the type of network employed. Particularly, public signalling systems are used between nodes of a public network and between public networks of different operators. Signalling System No. 7 is the only important example of a public signalling system. Access signalling systems are used between subscribers and edge nodes of public networks, e.g. between a radiotelephone and a base station subsystem (BSS). In fact, the most common digital access signalling schemes are Common Channel Signallin
Bailey Stuart S
Scott Barry
Lee Mann Smith McWilliams Sweeney & Ohlson
Nortel Networks Limited
Smith Craigton
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