This invention relates to digital communication networks having a network management system (NMS) for managing data traffic between user endpoints through intermediate core switches in the network and more particularly to the establishment of soft permanent virtual circuits (SPVC) across the network provisioned with means to identify any SPVC crossing a randomly selected core switch.
Digital communications networks, such as frame relay (FR) and asynchronous transfer mode (ATM), conventionally employ virtual circuits for the routing of data traffic across the integrated switching fabric of the network. When a virtual circuit is provisioned externally to provide a user with a quasi-dedicated route through the network it is known as a permanent virtual circuit (PVC). In digital networks a soft permanent virtual circuit is a communications medium which is permanently provisioned at the endpoints, but switched in the middle. The provisioning is controlled by the Communications Network Management Systems (NMSs) which also allow the creation, configuration, and display of the soft permanent virtual circuits (SPVCs) across the network. SPVCs traverse one or more core switches in order to allow two or more system end users to communicate. When an NMS establishes a SPVC, it requests a single switch at one of the desired endpoints of the SPVC to perform the necessary cross connections to reach the other endpoint of the SPVC. The endpoint switch uses routing software to establish the route for the SPVC, sets up a single cross connection on itself, then uses signaling software to request other switches to establish the rest of the cross connections. The signaling software sends only the minimum amount of information necessary to establish and maintain the cross connections such as; calling address, called address, bandwidth, traffic management characteristics, etc. The other switches signal back to the endpoint switch when they have completed the cross connections, and the endpoint switch then reports to the NMS that the SPVC has been established.
In a network in which many SPVCs exist, a user of the NMS can commonly select any switch in the network, and discover whether SPVC cross connections exist on that switch. Having discovered the existence of a cross connection, the user of the NMS should then be able to determine to which SPVC the cross connection belongs.
Identifying SPVCs in this way is useful, for example, for gauging the efficiency of the SPVC routing software, or for determining which edge switches, edge interfaces or SPVC end users are utilizing particular resources in the core of the network.
One solution to the problem of identifying SPVCs from randomly-selected cross connections in the middle of the network is not entirely satisfactory. It is possible for the NMS to identify the parent SPVC from a randomly selected point in the network without collecting and storing information on every SPVC cross connection in the network, but only storing information on the two endpoints of each cross connection, by a process of following cross connections and links forward or backward from the selected point, thus xe2x80x9cwalkingxe2x80x9d through the network until a known SPVC endpoint is reached. Each node within the network that is traversed by the SPVC connection must be queried by the NMS in order to trace the entire path of that connection.
Applying this solution to the example presented in FIG. 1, if the user selects the point B.2, the NMS first queries switch B and finds out that it is cross connected to point B.1. If it is known that point B.1 is physically or logically connected to point A.2, then the NMS can query switch A to determine what A.2 is cross connected to. When it learns that A.2 is cross connected to A.1, it compares A.1 to its list of SPVC endpoints and thus determines the identity of the SPVC (8 in this example) that crosses point B.2.
The shortcoming of this approach is that it is costly in terms of (a) the user""s time, (b) NMS processing resources, (c) NMS-to-switch bandwidth resources, and (d) switch processing resources. The larger the network (and therefore the more cross connections that are required for an SPVC to cross the network), the higher the cost of using this algorithm.
Accordingly, a solution which makes more efficient use of the systems resources, is required.
Therefore, in accordance with a first aspect of the present invention there is provided in a digital communications network for routing data between endpoint switches through a plurality of core switches, the network having a network management system (NMS). for provisioning a selected one of the endpoint switches to establish a switched virtual connection in the form of a switched virtual channel (SVC) or a soft permanent virtual circuit (SPVC) through the network, the SPVC or SVC being created by the core switches configuring cross connections therebetween, a method of identifying the SPVC at a selected core switch comprising: providing a database in said NMS for storing routing information; providing means at each of said core switches for collecting routing information; providing means in said NMS to collect said routing information from said core switches; and providing means in said NMS for identifying route information respecting said selected core switch.
In accordance with a second aspect of the invention there is provided in a digital communications network for routing data between endpoint switches through a plurality of core switches, said network having a network management system (NMS) for provisioning a selected one of said endpoint switches to establish a switched virtual connection in the form of a switched virtual channel (SVC) or a soft permanent virtual circuit (SPVC) through said network, said SVC or SPVC being created by said core switches configuring cross connections therebetween, a method of identifying said SPVC at a selected core switch comprising: providing an identifying tag to said SVC or SPVC upon initial establishment thereof; providing storage means in each of said core switches for storing relevant information; transporting said identifying tag through said core switches together with the cross connection configuration instructions and retaining said identifying tag in each of the storage means crossed; providing means in said NMS for accessing said storage means; and accessing said storage means in a selected core switch in response to a request to identify said SPVC or SVC thereat.