Abstract: The invention provides a method of determining the degree of network address translation (NAT) traversing required to dynamically establish a bearer path within or out of a Service Provider hosted Enterprise VoIP VPN. Each media end point in the Enterprise IP VPN has associated with it a chain of the identities of a hierarchy of NAT functions behind which it resides with respect to an SP public IP network over which the Enterprise VoIP is hosted. By comparing the respective NAT function identity chains for an originating end point and a destination end point, a call agent can determine what, if any, NAT functions need to be traversed in the bearer path between the end points.

Abstract: A method for determining the impact on a network of a fault in the network, comprises the steps of constructing a layered topological model of the network according to a predetermined protocol, receiving an indication of an erroneous event at a point in the network, and modelling the impact on the network and its services resulting from the event by navigating the topological model. The modelling step includes applying a priority weighting to an erroneous event to determine a priority order in which a sequence of erroneous events may be attended to. The priority order may be based on cost-effectiveness of carrying out a particular repair. The method may alternatively be used to determine the location of a fault with increased certainty by relating an event with a previous erroneous event. The method is preferably implemented by a programmed computer.

Abstract: A method for determining the impact on a network of a fault in the network, comprises the steps of constructing a layered topological model of the network according to a predetermined protocol, receiving an indication of an erroneous event at a point in the network, and modelling the impact on the network and its services resulting from the event by navigating the topological model. The modelling step includes applying a priority weighting to an erroneous event to determine a priority order in which a sequence of erroneous events may be attended to. The priority order may be based on cost-effectiveness of carrying out a particular repair. The method may alternatively be used to determine the location of a fault with increased certainty by relating an event with a previous erroneous event. The method is preferably implemented by a programmed computer.