A Generic Connection Admission Control in ATM Networks

In this paper we introduced a new call admission control (CAC) based on the virtual link with ultra wide bandwidth. Under the virtual link we mean that we have a reservoir that can accommodate an infinitive number of calls. So in each node we have to attach an auxiliary memory such as magnetic tapes with ultra high capacity to receive all the arriving calls. Traditional CAC will be replaced by two controllers: Virtual CAC (VCAC) and draft CAC (DCAC). The main function of VCAC is to collect all the arriving calls without negotiations depending on its high capacity. DCAC will import the calls from VCAC, sort them into classes according to their service category, give them the appropriate VPI over which they will be carried later on the least loaded link among the outgoing links and export them to the router according to the congestion level of the physical link. The proposed scheme looks like a transistor network. The collector is represented by VCAC, the emitter is represented by DCAC and finally the base is represented by the router. The idea of the proposed strategy can be explained as follows: All the calls are admitted to the virtual memory as they arrive without any delay with respect to the extra large memory size. The virtual memory is divided into segments according to the number of the services (audio, data, video, ...etc) and each segment is divided into a number of blocks size of each is a multiple of cell size (i.e. 53 octets), these blocks have the same number of VP's (for all outgoing links) to be connected with them later (the recommended bandwidth allocation strategy is service and path separation). The block capacity is too much greater than its associated link W. Once the block receives a new call it will spool (roll) it to its associated VP which belongs to the least loaded link, unless it becomes saturated. Once a new room appears in one of the associated VP's in any of the outgoing links it will be occupied by a new call. It is worth noting that the calls will be pushed out by applying the famous rule FIFO: first in first out