Symptom:
When switching interface from operating NIC to standby NIC in NIC switching mode where HUB in the network is running Spanning Tree Protocol (STP), it takes roughly 30 seconds to hold a communication with standby NIC.
Corrective action:
In the HUB where STP is running, establishing link by activating an interface does not necessarily mean to acquire communication instantly. In such environment, after a link has established on the port where NIC is connected, transmitting data is temporary constrained by transmission delay timer (Forward-time). In order to establish a communication instantly after switching to standby NIC, use the standby patrol. Standby patrol establishes a link regularly in both operation and standby NIC, so that the transmitting data would not be constrained by transmission delay timer (Forward-time) of STP.
