Low Latency 100-Gbps Ethernet IP Core User Guide

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ID 683160
Date 4/15/2021
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3.2.13.1. OctetOK Count Interface

The statistics counters include two 64-bit counters, RxOctetsOK and TxOctetsOK, which count the payload bytes (octets) in frames with no FCS, undersized, oversized, or payload length errors. The RxOctetsOK register maintains a cumulative count of the payload bytes in the qualifying received frames, and complies with section 5.2.1.14 of the IEEE Standard 802.3-2008. The TxOctetsOK register maintains a cumulative count of the payload bytes in the qualifying transmitted frames, and complies with section 5.2.2.18 of the IEEE Standard 802.3-2008.

To support payload size checking per frame, the LL 100GbE IP core provides an octetOK count interface instead of standard increment vectors. For most purposes, the number of payload bytes per frame is of more interest than the cumulative count, and an increment vector that pulses when the counter increments would be difficult to track. For each of these two registers, the IP core maintains two signals. A 16-bit signal provides a count of the payload bytes in the current frame, and the other signal pulses to indicate when the first signal is valid. The per-frame count is valid only when the valid signal is asserted. All signals in this interface are functional even if you do not turn on the corresponding statistics module.

Table 23.  OctetOK Count Interface SignalsThe signals for received frames are clocked by the clk_rxmac clock. The signals for transmitted frames are clocked by the clk_txmac clock.

Name

Signal Direction

Description

tx_inc_octetsOK[15:0]

Output

When tx_inc_octetsOK_valid is asserted, tx_inc_octetsOK[15:0] holds the count of payload bytes in the current valid frame.
tx_inc_octetsOK_valid

Output

Pulses to indicate that tx_inc_octetsOK[15:0] currently holds the number of payload bytes for the current transmitted frame, and that the current frame is a qualifying frame. A qualifying frame has no FCS errors, no oversized error, no undersized error, and no payload length error.
rx_inc_octetsOK[15:0]

Output

When rx_inc_octetsOK_valid is asserted, rx_inc_octetsOK[15:0] holds the count of payload bytes in the current valid frame.
rx_inc_octetsOK_valid

Output

Pulses to indicate that rx_inc_octetsOK[15:0] currently holds the number of payload bytes for the current received frame, and that the current frame is a qualifying frame. A qualifying frame has no FCS errors, no oversized error, no undersized error, and no payload length error.

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