Packet classification is essential for supporting advanced network services such as firewalls, quality-of-service (QoS), virtual private networks (VPN), and policy-based routing. The rules that routers use to classify packets are called packet filters. If two or more filters overlap, a conflict occurs and leads to ambiguity in packet classification. This study proposes an algorithm that can efficiently detect and resolve filter conflicts using tuple based search. The time complexity of the proposed algorithm is O(nW +s), and the space complexity is O(nW), where n is the number of filters, W is the number of bits in a header field, and s is the number of conflicts. This study uses the synthetic filter databases generated by Class-Bench to evaluate the proposed algorithm. Simulation results show that the proposed algorithm can achieve better performance than existing conflict detection algorithms both in time and space, particularly for databases with large numbers of conflicts.

This paper proposes a method of supporting behavioral decision-making with a rule-based system to be used for the design stage of service specifications or service scenarios based on a state transition model. We consider telecommunication services as service scenarios of state transitions. A state transition can be described as a transition rule that is represented as the notation of an IF-THEN rule : "if < condition > then < action >. " Thus, behaviors or service scenarios are assumed to be treated as a set of IF-THEN rules in this paper. In general, an "if < condition > then < action >" rule is called a production rule, and production rules are often used to represent knowledge in expert systems. Thus, rules treated in this paper are a kind of production rule. It is still difficult to decide if behaviors are concurrent, cooperative, or exclusive as a whole system when many service scenarios are combined, even if each rule is clearly described and easy to understand. When several service scenarios are combined, it is necessary for the sub-elements of each state transition to cooperate. The method proposed in this paper consists of the following techniques: (1) decompositions of a state transition to sub-elements, (2) rule descriptions for the decomposed sub-elements and the application of rules, (3) use of conflict and cooperation strategies, and (4) support for behavioral decision-making by showing recommendations for cooperative, exclusive, or concurrent behavior. We provide examples of telecommunication services to show the effectiveness of the proposed method in an easy-to-understand manner. We also show cooperative resolution in the interactions among several services.

A conflict detection support method for combining additional telecommunication services with existing services is proposed. In this method, telecommunication services are described by the STR (State Transition Rule) method which specifies a set of state transition rules. Though conflict detection in the past depended on manual analysis by the designer, with this method, conflict candidates are mechanically narrowed down and indicated to the designer. All conflicts between five actual telecommunication service descriptions are detected in an experiment using a system developed in line with the proposed method.