System and method for call-by-call source routing with rule-based fallbacks

A method for source based call-by-call routing of a call in a communication network, the method comprising the steps of:

• 14A) selecting a constrained routing for the call;
• 14B) determining an optimal feasible path and, where available, implementing the optimal feasible path for the call;
• 14C) where the optimal feasible path is unavailable, determining whether fallback routing is available for the call
• 14C1) where fallback routing is available, selecting a fallback routing and recycling to the step of choosing a constrained routing for the call (step 14A);
• 14C2) where fallback routing is unavailable, blocking transmission of the call;
• 14D) where the optimal feasible path is available, the network's attempting to allocate network resources along the optimal feasible path;
• 14E) where the resource allocation attempt is unsuccessful, blocking transmission of the call;
• 14F) where the resource allocation attempt is successful, establishing the call
• where fallback routing allows accommodation of preferential resource constraints and look-around-first call preemption and where routing without preemption is attempted before preemption.

A system for source based call-by-call routing of a call in a communication network, comprising:

• 27A) routing means for selecting a constrained routing for the call;
• 27B) optimal feasible path determining means, operably coupled to the routing means, for determining an optimal feasible path, availability of implementing the optimal feasible path, and, where available, for sending a signal to a network means, thereby causing the network means to implement the optimal feasible path;
• and
• 27C) fallback strategy means, operably coupled to the optimal feasible path determining means and the network means, for implementing a fallback strategy where one of:
• 27C1) the optimal feasible path is unavailable, and/or
• 27C2) the network is unsuccessful in implementing the optimal
• feasible path for routing the call where fallback routing allows accommodation Of preferential resource constraints and look-around-first call preemption and where routing without preemption is attempted before preemption.

A communication network system for routing an integrated traffic-type call in a communication network, comprising:

• 41A) a requested resource constraint determiner, operably coupled to receive a call, for providing at least one of:
• a first output and a second output, wherein the first output is a reoptimized call and the second output is an established call, for implementing requested resource constraints with non-preemptiveness and minimized cost for the call to provide the established/reoptimized call,
• 41B) a first acceptable resource constraint determiner, operably coupled to receive the call, to receive the second output (established call) of the requested resource constraint determiner, for, where one of:
• establishing the call is unsuccessful or reestablishing/appending the call is required, implementing acceptable resource constraints with non-preemptiveness and minimized cost to provide a non-preemptive output and a first preemptive output,
• 41C) a second acceptable resource constraint determiner, operably coupled to receive the first non-preemptive output, for implementing acceptable resource constraints with non-preemptiveness and minimized delay to provide a non-preemptive delay-minimized output,
• 41D) a third acceptable resource constraint determiner, operably coupled to receive the first preemptive output, for, where step 41(B) is unsuccessful, implementing acceptable resource constraints with preemptiveness and minimized cost to provide a second preemptive cost-minimized output, and
• 41E) a fourth acceptable resource constraint determiner with preemptiveness, operably coupled to receive the second preemptive cost-minimized output, for implementing acceptable resource constraints with preemptiveness and minimizing delay to provide a preemptive delay-minimized output.

A method for routing a call in a communication network system, wherein ".sub.-- -.sub.-- " represents two letters separated by a dash, the letters being selected from X and I to represent exclusion (X) and inclusion (I) from/with requested resource constraints (first letter) and acceptable resource constraints (second letter), respectively, the method comprising the steps of:

• 42A) the network system's determining how many resource attribute values are specified as required by the user;
• 42B) where one required resource attribute value is specified by a user for a given resource attribute, the network system's assigning I--I to the required resource attribute value, and X--X to all other resource attribute values belonging to the same resource attribute;
• 42C) where greater than one required resource attribute value is specified for a given resource attribute, the network system's classifying the selection as an invalid configuration;
• 42D) where the number of required resource attribute values for a given resource attribute is zero, the network system's determining how many resource attribute values are preferred;
• 42E) where one or more resource attribute values for a given resource attribute are preferred, the preferred resource attribute values being assigned I--I, any don't.sub.-- care resource attribute values (X--I) being assigned X--I, and any don't.sub.-- use resource attribute values being assigned X--X;
• 42F) where the number of required resource attribute values for a given resource attribute is zero and where the number of preferred resource attribute values for the same resource attribute is zero, the network system's determining how many don't.sub.-- care resource attribute values are specified;
• 42G) where one or more resource attribute values are specified as don't.sub.-- care, the don't.sub.-- .sub.-- care resource attribute values being assigned I--I, and any don't.sub.-- use resource attribute values being assigned X--X;
• and
• 42H) where the number of required resource attribute values for a given resource attribute is zero, where the number of preferred resource attribute values for the same resource attribute is zero, and where the number of don't.sub.-- care resource attribute values for the same resource attribute is zero, the network system's classifying the selection as an invalid configuration.