Altera Low Latency 40-Gbps Ethernet MAC and PHY MegaCore Function User Manual
Page 78
If you turn on bit [1] of the
LINK_FAULT_CONFIG
register, the IP core conforms to Clause 66 of the IEEE
802.3-2012 Ethernet Standard and transmits the fault sequence ordered sets in the interpacket gaps
according to the clause requirements.
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.
If you turn off Enable link fault generation, the
remote_fault_status
and
local_fault_status
signals are still available, but they always have the value of 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
These signals are available only if you turn on Enable link fault generation in the LL 40-100GbE parameter editor
or you upgrade your IP core from an earlier release in which the signals are available in any case.
Signal Name
Direction
Description
remote_fault_status
Output
Asserted when remote fault is detected in RX MAC.
If you turned off Enable link fault generation in your IP core
variation in an earlier release, and then upgraded to the current
release, this signal is present but is tied low (always has the value
of 0).
This signal is clocked by
clk_status
.
local_fault_status
Output
Asserted when local fault is detected in RX MAC.
If you turned off Enable link fault generation in your IP core
variation in an earlier release, and then upgraded to the current
release, this signal is present but is tied low (always has the value
of 0).
This signal is clocked by
clk_status
.
unidirectional_en
Output
The IP core asserts this signal if it includes Clause 66 support for
remote link fault reporting on the Ethernet link. Connects to the
Unidir Enable
field in bit [1] of the
LINK_FAULT_CONFIG
register
at offset 0x405.
This signal is clocked by
clk_txmac
.
If you turn off Enable link fault generation this signal is not
available.
UG-01172
2015.05.04
Link Fault Signaling Interface
3-33
Functional Description
Altera Corporation