Data Sheet

Inline Functions—Ethernet Controller I210
317
Credits - Regulates the bandwidth allocation to user priorities, credits represent a single byte. The
transmission of a queue in SR mode is defined by the amount of credits assigned to that queue
QueueFrames - Each queue has an indication whether there are queued frames for that queue
Launch Time - Defines the time to launch the packet for time based arbitration
Mode - While in Qav mode each queue is configured to be either in priority mode or SR mode
Table 7-46 lists the arbitration modes as controlled by the TQAVCTRL register followed by a flow
diagram that illustrates the arbitration scheme for Qav mode.
Table 7-46. Transmission Arbitration
TransmitMode DataTranARB DataTranTIM Functionality
0 (Legacy) X X
Single packet buffer for all 4 queues. Packets are transmitted
at the same order they are fetched from host memory.
1 (Qav) 0 (Strict Priority) 0 Strict priority queuing without any scheduling.
1 (Qav) 0 (Strict Priority) 1 (Launch Time)
Strict priority queuing while SR queues are subjected to
launch time policy.
1 (Qav) 1 (Credit Shaper) 0
Strict priority queuing while SR queues are subjected to Credit
Shaper policy.
1 (Qav) 1 (Credit Shaper) 1 (Launch Time)
Strict priority queuing while SR queues are subjected to Credit
Shaper policy plus launch time.