Download 10-Gbps Ethernet MAC MegaCore Function User Guide

Chapter 7: Functional Description
Error Handling (Link Fault)
7–21
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 9–10 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 (32-bit) or 0x9c01008000 (32-bit
data and 4-bit control), the RS RX sets link_fault_status_xgmii_rx_data to 01. The
RS TX starts sending the remote fault signal—0x9c000002 (32-bit data) or
0x9c01000001 (32-bit data and 4-bit control)—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)
MAC
Tx
Client
Interface
RS Tx
XGMII
2
link_fault_status_xgmii_rx_data
XAUI /
XAUI /
10GBASE-R 10GBASE-R
PHY
External
PHY
Network
Interface
Remote
Partner
Remote Fault (0x9c000002)
MAC
Rx
RS Rx
Local Fault (0x9c000001)
August 2014
Altera Corporation
10-Gbps Ethernet MAC MegaCore Function User Guide