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The ethernet model in COSI is divided in two layers: PHY and MAC. At the physical level, the delay is due to the propagation delay of the wires and the dealy due to the signaling speed. Notice that this contribution is a per-bit contribution. A the mac level, the protocol overhead is also taken into account. Sensors and actuators are connected to switches. Each sensor has a dedicated port on a switch therefore there is not bus contention. However, when multiple inputs want to reach the same ouptut, the switch uses a round-robin arbitration scheme among them. Therefore, the worst case delay for a packet arriving at a switch depends on the traffic conditions at the other inputs.
Generated on Sun Sep 7 18:37:45 2008 for COSI by
 1.5.4
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