Altera 10-Gbps Ethernet MAC MegaCore Function - Manual (Page 87)

7–20 Chapter 7: Functional Description
Error Handling (Link Fault)
10-Gbps Ethernet MAC MegaCore Function User Guide February 2014 Altera Corporation
7.7.2.2. PFC Frame Transmission
PFC frame generation is triggered through the avalon_st_tx_pfc_gen_data signal.
Set the respective bits to generate XOFF or XON requests for the priority queues.
Refer to
Table 9–9 on page 9–18 for more information about the signal.
For XOFF requests, you can configure the pause quanta for each priority queue using
the pfc_pause_quanta_n registers. For an XOFF request for priority queue n, the MAC
TX sets bit n in the Pause Quanta Enable field to 1 and the Pause Quanta n field to the
value of the pfc_pause_quanta_n register. You can also configure the gap between
successive XOFF requests for a priority queue using the pfc_holdoff_quanta_n
register. Refer to
Table 8–2 on page 8–2 for more information about these registers.
For XON requests, the MAC TX sets the pause quanta to 0.
7.8. Error Handling (Link Fault)
The 10GbE MAC includes a reconciliation sublayer (RS) located between the MAC
and the XGMII that handles local and remote faults.
When the local PHY reports a local fault (0x9c000001), the RS RX sets
link_fault_status_xgmii_rx_data
to 01. The RS TX starts sending the remote fault
signal (0x9c000002) to the PHY, which the remote partner eventually receives.
When the local PHY receives a remote fault signal, the RS RX sets
link_fault_status_xgmii_rx_data
to 10. The RS TX transmits IDLE signal
(07070707). When the RS TX starts sending the remote fault or IDLE signal, all data
sent by the MAC TX is lost.
If the client and the remote partner both receive valid data in more than 127 columns,
the RS RX sets link_fault_status_xgmii_rx_data to 00.
Figure 7–11 shows fault signaling.
Figure 7–11. Fault Signaling
Remote Fault (0x9c000002)
Idle (07070707)
Remote Fault (0x9c000002)
Client
Interface
MAC
Tx
RS Tx
MAC
Rx
RS Rx
2
link_fault_status_xgmii_rx_data
XAUI /
10GBASE-R
PHY
External
PHY
Remote
Partner
XAUI /
10GBASE-R
Network
Interface
Local Fault (0x9c000001)
XGMII