Altera 40-Gbps Ethernet MAC and PHY MegaCore Function - Manual (Page 85)

MAC and the XLGMII or CGMII to manage local and remote faults. Link fault signaling on the Ethernet
link is disabled by default but can be enabled by the
Enable Link Fault Sequence
register. When
enabled, the local RS TX logic can transmit remote fault sequences in case of a local fault and can transmit
IDLE control words in case of a remote fault. An additional configuration register (
MAC/RS link fault
sequence configuration
) is provided to select the type of information to be transmitted in case of a
local or remote fault. Using the configuration bits, you can send remote fault sequence ordered sets, IDLE
control words, or regular traffic in the case of a local or remote fault.
The RS RX logic sets
remote_fault_status
or
local_fault_status
to 1 when the RS RX block receives
remote fault or local fault sequence ordered sets. When valid data is received in more than 127 columns,
the RS RX logic resets the relevant fault status (
remote_fault_status
or
local_fault_status
) to 0.
Figure 3-30: Link Fault Signaling Example
Idle
Remote Fault Sequence
Local Fault Status, Remote Fault
Status & Fault Configuration
Normal mii Traffic
mii_d[319:0]
mii_c[39:0]
The IEEE standard specifies RS monitoring of RXC<7:0> and RXD<63:0> for Sequence
ordered_sets
.
For more information, refer to Figure 81–9—Link Fault Signaling state diagram and Table 81-5—Sequence
ordered_sets
in the IEEE 802.3ba 2010 100G Ethernet Standard . The variable
link_fault
is set to
indicate the value of an RX Sequence
ordered_set
when four
fault_sequences
containing the same
fault value are received with fault sequences separated by less than 128 columns and with no intervening
fault_sequences
of different fault values. The variable
link_fault
is set to OK following any interval of
128 columns not containing a remote fault or local fault Sequence
ordered_set
.
Table 3-8: Signals of the Link Fault Signaling Interface
Signal Name Direction Description
remote_fault_from_
rx
Output Asserted when remote fault is detected in RX MAC. Available in
RX-only variations.
local_fault_from_rx
Output Asserted when local fault is detected in RX MAC. Available in RX-
only variations.
remote_fault_to_tx Input Input to the TX MAC. Asserted when remote fault is detected.
Visible in TX-only variations and used internally in duplex IP core
variations.
local_fault_to_tx Input Input to the TX MAC. Asserted when local fault is detected.
Visible in TX-only variations and used internally in duplex IP core
variations.
remote_fault_status Output
Asserted when remote fault is detected in RX MAC in a duplex IP
core variation. In duplex IP core variations,
remote_fault_from_
rx
is connected internally to
remote_fault_to_tx
, and this signal
is available externally as
remote_fault_status
.
3-38 Link Fault Signaling Interface
UG-01088
2014.12.15
Altera Corporation Functional Description
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