To move traffic across the OUSPs, you must create a service circuit between interfaces on the units. Regardless of whether you are using Gigabit Ethernet or Fibre Channel, the setup is similar: Define the interfaces to be used at either end of the connection and the bandwidth to be used between them. The connection can be set up symmetrically or asymmetrically, and can be defined by the number of STS (synchronous transport signal) or STM (synchronous transfer module) channels or in megabytes.
The bandwidth used can be created as reserved, unpreemptable or preemptable. Reserved creates bandwidth that can't be used by anyone else and will fail over in case of outage on the primary fiber. This obviously requires a second Sonet interface.
For my testing, I created a reserved Fibre Channel circuit and passed traffic over the circuit created from a Spirent Communications SmartBits 600 equipped with Fibre Channel and Gigabit Ethernet interfaces. Pulling the OC-48 connection on the unit caused the traffic to jump to the OC-12 connection. A few minutes after the OC-48 was reconnected, the OUSPs moved the traffic back from the OC-12.
Unpreemptable service sets aside bandwidth that is guaranteed just as reserved is, except it won't fail over during an outage. Preemptable bandwidth is best effort, can be shared by circuits and won't fail over.
Flow control can be set up on Ethernet or Fibre Channel connections but in each case performs different tasks. On Gigabit Ethernet connections with flow control turned on, the OUSP performs QoS (Quality of Service) on the circuit and allows priority traffic to be placed on the circuit first. When it's turned off, every packet is placed as best effort.