This read-create value, in microseconds, configures the Fixed Round Trip Time for the ABR connection, representing the sum of fixed propagation delays between the source and destination network. An admin sets this to give the ABR rate-control algorithm an accurate baseline round-trip time, which affects how quickly the algorithm can safely ramp rate changes without overreacting to normal propagation delay. For example, on a long-haul ATM connection with significant physical distance between endpoints, the admin would configure a correspondingly larger fixed round trip time so the ABR control loop doesn't misinterpret normal propagation delay as congestion.