At+t Corp.

At&t Bell Laboratories

AT&T Intellectual Property I, LP

Bell Telephone Laboratories

At&t Company

At&t Communications

Gerald Richard Ash

Jiayu Chen

Saul Daniel Fishman

Anurag Singh Maunder

Alan Eugene Frey

Jin-Shi Chen

Andrew W Peck

Sanjeev K Deora

James J Gallagher

Billy B Oliver

David F McGuigan

Young Lee

Kenneth K Chan

Steven D Schwartz

Richard H Cardwell

Robert A Gerritsen

David Zerling

The present invention concerns a technique for providing Class-of-Service Routing in an ATM network () that utilizes the Private Network-Network Interface (PNNI) protocol. An originating node seeking to route a call to a terminating node does so by initially determining the class-of-service and then selecting a shortest length path there-between. Each successive link on the selected path is examined for sufficient available bandwidth and available depth (i.e., bandwidth not reserved for other services) for the Class-of-Service of the call. If every link possesses sufficient available bandwidth, then the call passes on the selected path. Otherwise, should a link on the selected path lack sufficient bandwidth and available depth, then a crankback message is sent to the originating node, and the originating node selects the next shortest path. Thereafter, the process of examining each link for sufficient bandwidth is repeated. If no path is found, the call is ultimately blocked.

PNNI-based mult-link shortest path class-of service routing technique

The present invention concerns a technique for providing Class-of-Service Routing in an ATM network ( ) that utilizes the Private Network-Network Interface (PNNI) protocol. An originating node seeking to route a call to a terminating node does so by initially determining the class-of-service and then selecting a shortest length path there-between. Each successive link on the selected path is examined for sufficient available bandwidth and available depth (i.e., bandwidth not reserved for other services) for the Class-of-Service of the call. If every link possesses sufficient available bandwidth, then the call passes on the selected path. Otherwise, should a link on the selected path lack sufficient bandwidth and available depth, then a crankback message is sent to the originating node, and the originating node selects the next shortest path. Thereafter, the process of examining each link for sufficient bandwidth is repeated. If no path is found, the call is ultimately blocked.

PNNI-based multi-link shortest path Class-of Service routing technique

The priority of the flow of packets representing calls or other connection requests within a packet network ( ) is determined from the Class-of-Service of the call. Upon receipt of a call, a recipient router ( ) identifies available paths, typically by exchanging messages with the other routers in the network. After selecting the path, the recipient router or centralized bandwidth broker determines whether the links comprising the selected path have available bandwidth for the class of service of the call. If so, the router routes the call to the next hop along the path. Otherwise, the router selects another path(s) and checks whether the links on the path possess sufficient bandwidth for the class of service of the call.

Internet protocol (IP) class-of-service routing technique

An originating switch ( ) in a packet-based telecommunications network ( ) routes calls to a terminating switch using the combination of Success-to-the Top (STT) and Class-of-Service criterion. In routing a call to the terminating switch, the originating switch checks for available bandwidth for the class of service of the call on the direct path ( ) between switches. If the path has available bandwidth, the originating switch routes on the direct path. Otherwise, the originating switch searches for the most recently successful one of a plurality the via switches ( ) linking the originating and terminating switches to determine whether that via switch can successfully route the call to the terminating switch. If the most recently successful one of the via switches possesses available bandwidth to route the call in accordance with its class of service, the originating switch selects that via switch to route the call. Otherwise, if the most-recently successful via switch can not route the call, the originating switch searches for a next successful via switch. If none of the via switches can successfully route the call in accordance with its class of service, the originating switch will either attempt a route advance or crankback the call.

Success-to-the-top class of service routing

The routing of calls in a telecommunications switching system (12.sub.1, 12.sub.2) comprised of one or more fabrics (22.sub.1, 22.sub.2, 22.sub.3) controlled by corresponding fabric controllers (26.sub.1,26.sub.2 and 26.sub.3, respectively) is carried out by a routing processor (28) independent of the fabrics. The routing processor actually selects the route for each call by specifying a channel to a neighboring switching system to carry the call. Further, the routing processor has the capability to respond to queries from other switching systems regarding trunk group status and traffic load to enable the processor to assist the routing processor of the other switching system to make routing decisions. By implementing fabric independent routing, routing processing is re-used for new fabric capacity, and is readily extended to accommodate new service types, such as bursty data services. Fabric independent routing achieves lower development cost by avoiding re-development of routing functions on new fabric controllers, as they are added, and the addition of new routing features is made on a single routing processor function versus multiple fabric controllers. Fabric independent routing allows routing processing to be implemented on processors with essentially unlimited real-time and memory resources by riding the processor technology curve, and achieves performance advantages such as reduced call set up delay and improved overall switch reliability.

Method and apparatus for achieving fabric independent routing technique

The routing of calls from one network (100) to another network (170) may be accomplished by tracking the call completion history over each trunk group (174.sub.1 -174.sub.2) connecting the networks. From a knowledge of the call completion history for each route, a Completion Rate Factor (CRF), representing the ratio of completed calls to all calls attempted is computed. The route having the CRF representing the highest number of completions is then selected. Typically, the process is dynamic, so that if the selected route no longer has the highest number of completions, then the route previously found to have the highest number of call completions is selected. The concept of completion rate factor routing can be extended to multiple carriers to yield a carrier completion rate feature routing technique. Routing may also be completed in accordance with network congestion to route advance a call.

Automatic routing technique

Local/toll dynamic routing integration is achieved within a telecommunications network (14) that includes at least one dynamic routing local switching system (24-1) for receiving incoming call and a plurality of toll switching systems (27-1 through 27-7) at least one of which is associated with each local switching system. For each incoming call, the local switching system (24-1) derives a set of Class-Of-Service (COS) parameters indicative of the class-of service associated with the call. In accordance with the COS parameters, the local switching system (24-1) determines whether each incoming call is a featured call, requiring routing to the toll switching system associated therewith, or a non-featured call. Featured calls are routed to the toll switching system associated with the local switching system for feature processing, whereas non-featured calls are routed by the local switching system itself in accordance with the COS parameters, thus relieving the load on the associated toll switching system.

Class-of-service automatic routing

A telecommunications network (10) includes an Originating Switching System (12.sub.1) and a Terminating Switching System (12.sub.2) linked by a plurality of trunks (20.sub.1 -20.sub.4). For each incoming call it receives, the Originating Switching System establishes a Circuit Selection Capability Indicator (CSCI) value that determines what enhancement, if any, the Originating Switching System will provide to the call. The Originating Switching System also utilizes the CSCI value to select an appropriate trunk that is compatible with a type of call enhancement, if any, to route the call to the Terminating Switching System which also enhances the call in accordance with the CSCI value. Determining the call enhancement in accordance with the CSCI value allows different types of calls which are routed on the same trunk to get different call quality enhancements, depending on the call type.

Method for selectively routing enhanced calls

A telecommunication network may be arranged in accord with the invention so that a change in provisioning data occurring at one element of the network is automatically supplied to the other elements of the network, thereby eliminating the need of having a network administration facility to communicate manually the change to the other network elements. For example, if a local central office switch is rehomed from a first toll switch to a second toll switch, then the first and second toll switches form messages respectively characterizing the rehome and then send the messages to each of the other network toll switches so that the other toll switches may update their respective routing and trunking data relating to the rehomed switch. The network is also arranged to implement a rule-based, end-to-end routing scheme which automatically selects a routing path from multiple candidates based on (a) class-of-service parameters and (b) availability of network capacity. The automatic selection of a routing path thus replaces the provisioning of routing data in the toll switches, which data was priorly needed to select the appropriate routing path.

Automatic provisioning of trunking and routing parameters in a

The routing of calls of different classes of services as well as the administration thereof is enhanced by associating each such class of service with a number of parameters common to such services, such that each class of service, as well as a new class of service, may be readily identified by its respective parameter values. Accordingly, the routing and administration of calls of different classes of services may be handled in a systematic, straight forward manner so that basic network capabilities may be made available to various services using an administratively defined menu like structure. In addition, such class of service advantageously partitions network bandwidth allocation, call routing priority, voice/data transport, and traffic data registers into respective classes of services.

Communications network class-of-service routing

The architecture of a communication network comprising a plurality of nodes interconnected by a transmission facility having a bandwidth divisible into channels of respective bandwidths, e.g., optical fiber, is enhanced by fully sharing the network bandwidth among the network nodes, such that each pair of nodes, on periodic basis, dynamically establishes respective direct links to each of the other network nodes, in which a direct link is formed from a group of channels obtained from the network bandwidth. The remaining bandwidth is then used to form a pool of bandwidth which is shared among the network nodes on a dynamic basis, such as, for example, establishing a communication path between a pair of nodes to route a call from one node to the other node of the pair of nodes.

Fully shared communications network

An arrangement for routing calls from a source switch to a destination switch in a telecommunications network. If a direct trunk is available between the two switches, that trunk is used. Otherwise, the destination switch is queried to obtain availability data of trunks to that switch from intermediate switches of the network. This availability data is then compared with availability data of trunks from the source switch to the intermediate switches. A route is then selected using an intermediate switch having available trunks from the source switch and to the destination switch. If a route using lightly loaded trunk groups is available, that route is selected in preference to the use of a route using more heavily loaded trunk groups. Advantageously, routing is performed to dynamically optimize selection of a route based on the current state of the network.

Real-time network routing

A communications network is arranged so that an external switching office is connected to the network via multiple ingress/egress nodes such that an originating node which receives a call destined for the external office may route the call through the network to one of the ingress/egress nodes in accordance with a particular class (type) of routing specified in one of a number of routing treatments. Such routing treatments are associated with the external office and at least identify respective ones of the ingress/egress nodes connected to the external office.

Communications system ingress and egress arrangement

A nonhierarchial switching system employing a modified unified algorithm for developing link sizes for paths that connect switches in the system and routing sequences for the switches in the system, and further employing means for updating the routing sequences to minimize potential blocking in the network. In one embodiment, the modified unified algorithm develops improved link size determinations by taking advantage of traffic sensitive dynamic routing on the alternate paths available in the nonhierarchial switching system for connecting any switch to any other switch in the system. Updating of the routing sequences is achieved in that embodiment by evaluating the least loaded path for each potential connection of two switches in the system and, when appropriate, by installing the least loaded path as the second choice path in the routing sequence for that potential connection.

Integrated network controller for a dynamic nonhierarchical routing

In a network for routing traffic from an originating node to a terminating node, it is common to provide alternate routes in order to increase the number of route choices between the originating and terminating nodes. The Bell System toll network employs a hierarchical alternate routing arrangement wherein various nodes, or control switching points (CSPs), are rank ordered for defining a process of routing calls through the network, whereby some CSPs are prohibited from routing traffic through other CSPs. Hence, known hierarchical alternate routing arrangements tend to inhibit route choices, which tends toward longer, and hence more costly, routes. Such problems tend to arise from the limited capability of electromechanical switching equipment. But with the increasing use of electronic stored program controlled CSPs, they can be solved with our alternate routing method which allows route choices without regard to network hierarchy. A plurality of routing sequences is generated, each route sequence including a plurality of route choices and being time sensitive to traffic demands, subject to a grade of service constraint and used for some predetermined time interval during which the sequence tends to mitigate network cost. An appropriate routing sequence is selected and in response thereto a signal is generated to identify a route choice. The route choice signal is then extended, perhaps on a call-by-call basis, to a node which is intermediate to the originating and terminating nodes for identifying the route to be followed in completing the call. In the event a link on the route choice is unavailable, a crankback signal is returned to the originating node. Responsive to the crankback signal, a second route choice from the routing sequence may be attempted from the originating node. This flexible, time sensitive arrangement tends toward increasing the number of route choices and toward mitigating or reducing route length and hence route cost.

Growing community of inventors

West Long Branch, NJ, United States of America

Gerald Richard Ash