Altera 50G Interlaken MegaCore Function - Manual (Page 42)

also not end of packet data. This data follows the data burst transfered in cycles 1 and 2, within the same
packet the IP core is sending to channel 2.
In cycle 6, the IP core sends a start of packet, single-cycle data burst to channel 3.
In cycles 7 and 8, the IP core sends a two-cycle data packet in one two-cycle burst. In cycle 8, the second
data cycle, the IP core drives the value of two on
irx_num_valid[2:0]
and the value of 4'b1011 on
irx_eopbits
, to tell the application that in this clock cycle, the two most significant words of the data
symbol contain valid data and the remaining words do not contain valid data, and that in the second of
these two words, only the three most significant bytes contain valid data.
50G Interlaken IP Core RX Errored Packet Handling
The 50G Interlaken IP Core provides information about errored packets on the RX user data transfer
interface through the following output signals:
•
irx_eopbits[3:0]
—If this signal has the value of 4'b0001, an error indication arrived with the packet
on the incoming Interlaken link: the EOP_Format field of the control word following the final burst of
the packet on the Interlaken link has this value, which indicates an error and EOP.
•
irx_err
—The 50G Interlaken IP Core checks the integrity of incoming packets on the Interlaken link,
and reports the packet corruption errors it detects on the RX user data transfer interface in the
irx_err
output signal.
In both cases, the application is responsible for discarding the relevant packet.
The
irx_err
signal reflects the following errors:
• CRC24 errors
• Loss of lane alignment
• Illegal control word
• Illegal framing pattern
• Missing SOP or EOP indicator
The
irx_err
output signal is aligned with
irx_eopbits
, and is always asserted when
irx_eopbits
has
the value of 4'b0001. However,
irx_eopbits
can have the value of 4'b0001 when
irx_err
is not asserted,
if the error indication arrived on the Interlaken link but the 50G Interlaken IP Core does not detect any of
the listed integrity issues in the incoming packet communication.
The
irx_err
signal indicates approximately where an error occurs: the corruption could have occurred at
the SOP of the current packet, in some later cycle in the payload of the current packet, in a packet that is
interleaved with the current packet, or in the current EOP cycle. When the IP core identifies an error in
the data it receives on the Interlaken link, it marks every packet currently open on the link as errored,
rather than attempt to associate the error with a specific channel. Therefore, the application need not drop
any packets that are not marked explicitly as errored using one of the two mechanisms.
The
irx_err
signal asserts one time only, whether a single error or multiple errors occurred in the packet.
If the current EOP cycle data is corrupted so badly that the EOP indication is missing, the
irx_err
error
indication is aligned to the next EOP. If an error occurs during an IDLE cycle, the
irx_err
is aligned to
the next EOP.
The application is responsible for discarding packets it receives from the IP core with
irx_err
asserted
during the EOP cycle, just as it is responsible for discarding packets it receives from the IP core with
irx_eopbits
set to 4'b0001. The application is not responsible for tracking the open packets interleaved
with the errored packet — the 50G Interlaken IP Core asserts
irx_err
in the EOP cycle of every
4-16 50G Interlaken IP Core RX Errored Packet Handling
UG-01140
2015.05.04
Altera Corporation Functional Description
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