The bandwidth of traffic sent from the sensor to the brain is expected to be a small proportion of the traffic received by the sensor. This proportion will vary significantly by the application profile of that traffic and cannot be quantified or predicted, however, we offer the guideline of between 0.5% and 5% of the received traffic.
For example, an S2 sensor receiving 50Mbps of traffic spread across both interfaces, we would expect that sensor to be sending between 250kbps and 2.5Mbps to the Brain. Unusual traffic patterns (e.g. high proportions of application traffic) may affect this estimate.