Dynamic and intelligent congestion controls for TCP over ABR and UBR services on ATM networks

Asynchronous transfer mode (ATM) is a target switching technology for B-ISDN since it can converge telephone and data packet networks. Since data communication networks have been widely spread and used, we have faced congestion control problems.; Feedback mechanisms are used for controlling ABR service traffic. Quantum Flow Control (QFC) is a protocol using a credit-based scheme to guarantee zero cell loss. This document provides an equation to calculate the minimum buffer space to ensure no cell loss. It also provides an equation to calculate the expected overhead rate for QFC in any traffic situation with higher priority traffic such as CBR and VBR. Thus networks can easily compute the desired frequency of sending credit information. In case of heavy network congestion, a credit-based scheme requires different channel access criteria to avoid unfairness. Using new scheduling disciplines developed by the author, a switch's workload can be decreased and still provides fairness.; Unlike ABR, UBR depends entirely on a higher layer to provide against loss of packets. Thus there is no need of an expensive and complex method to control its flow Current packet discard schemes such as EPD and PPD only improve network efficiency for delivery of damaged packets. Consecutive packet discard (CPD), developed by the author, provides an end-to-end UBR connection higher efficiency and is more robust in the worst case of heavy network congestion.