Ant Colony Behaviour as Routing Mechanism to Provide Quality of Service

Quality of Service (QoS) guarantees must be supported in a network that intends to carry real-time and multimedia traffic effectively. The effort of satisfying the QoS different requirements of these applications has resulted in the proposals of several QoS-based frameworks, such as Integrated Services (IntServ) [1], Differentiated Services (DiffServ) [2], and Multi-Protocol Label Switching (MPLS) [6]. The support of QoS services is underpinned by QoS Routing (QoSR), known as the task of determining paths that satisfy QoS constraints [4]. There exist many QoSR algorithms and also some first applications of ant-inspired algorithms. In this paper, we propose a QoSR scheme called AntNet-QoS. Taking inspiration from Ant Colony Optimization (ACO) ideas, and in particular from the AntNet routing algorithm [5] (which was designed for best-effort IP networks), AntNet-QoS is able to provide routes under QoS constraints in a DiffServ network, as well as under traditional hopby-hop IP routing conditions. In the DiffServ model [2], QoS conditions to be satisfied are specified in Service Level Agreements (SLA) [7]. The SLA specify what Classes of Traffic (CoT) will be provided, what guarantees are needed for each class, and how much data will be sent for each class. Using the DiffServ model a variety of CoT can be defined based upon the DiffServ Code Point (DSCP) field. DiffServ allows for a maximum of 14 different CoT. In AntNet-QoS, we will consider four of these: an Expedited Forwarding (EF) class to transport real-time traffic, two Assured Forwarding (AF1 and AF2) classes for traffic with different flavors for losses, and, as usual, a Best Effort (BE) class for traffic with no QoS requirements. In the rest of this paper, we describe the general characteristics of the algorithm and briefly discuss our future plans for implementation and testing.