Hard Real-time Communication of Periodic Messages on a Switched Ethernet

Switched Ethernet provides many features for real-time communications, but it does not guarantee the timely delivery of real-time messages. This paper proposes a message transmission model for hard real-time communications of periodic messages on a switched Ethernet and also proposes algorithms to schedule the messages to be transmitted within their deadlines in the case of cut-through switches and store-and-forward switches, respectively. When a node wants to transmit a new periodic message, it checks first whether the message can be allocated a suitable bandwidth without affecting the already-scheduled messages. The proposed scheduling algorithm is a distributed one and is performed by the source and the destination nodes without the modification of the operational features of the standard Ethernet switch.