Credit determination for flow control in FC-AL

Fibre channel, a computer communications protocol designed to meet many requirements related to the ever increasing demand for high performance information transfer, is one of the candidate architectures for a "unified network". Arbitrated loop is one of the basic fibre channel topology. lt is a cost-effective way of connecting up to 127 ports in a single network. Different from switched fabric, the media is shared among the devices, limiting each device's access. Flow control deals with the problem of where a device receives frames faster than it can process them. When this happens, the result is that the device is forced to drop some of the frames. Credit is an important service parameter for fibre channel flow control. Configuring the credit reasonably can avoid buffer overflow in nodes. This paper analyzes the relationship between the method to determine login credit and the scheme to allocate message transmission bandwidth in fibre channel-arbitrated loop. The optimization of credit has been derived on the traffic load balance of each node. This study is based on the features of hard real-time communications in avionics environments.