This read-only Gauge32, in megabits per second, reports the current outbound bandwidth on internal ports being delivered to the protected network. It gives an admin a bandwidth view of what's actually getting through to internal hosts after filtering. For example, an admin sees internalPortBitTransmitRate much lower than externalPortBitReceiveRate during an attack, confirming the appliance is successfully dropping most malicious traffic before it reaches the internal network.