A distributed routing and access control scheme for ATM networks

A proposed model of an ATM access node is extended to describe a network featuring a node by node admission control and routing strategy. A hierarchical dynamic resource allocation scheme is periodically applied at each node to every outgoing link, in order to reassign link capacity partitions among various service classes. Local access control rules compute the maximum number of connections of each class that a link can accept, by using the assigned capacity. A call request packet is generated with every connection request, and it is sent along a path from the source to the destination node. Each node traversed checks the presence of the resources needed to accept a new connection, by using the local access control rule. A connection is accepted only if every node on the path has enough resources to support it (also maintaining the quality of service for connections in progress), and it is refused otherwise. The path of the request packet is chosen by using a distributed routing strategy. At every node traversed, an output link is chosen by minimizing a cost function composed by two terms: a “local” and a “global” one. The local term takes into account the situation of the node by using a simple calculation, whereas the global term holds the aggregate information about the situation of the network, and it is updated and passed along periodically by every node. A complete description of the global scheme and simulation results are reported and discussed