100 Gbit/s, 40 Gbit/s, 10 Gbit/s and 1 Gbit/s / 10 Gbit/s MAC

Napatech Link-Capture™ Software Features

Intel® PAC
Napatech SmartNIC
Content Type
Feature Description
Capture Software Version
Link™ Capture Software 12.11

In this chapter

This chapter describes the 100 Gbit/s MAC, the 40 Gbit/s MAC, the 10 Gbit/s / 25 Gbit/s MAC, the 10 Gbit/s MAC and the 1 Gbit/s / 10 Gbit/s MAC, which receive/transmit the data stream from/to the PHY, and generate/terminate an internal frame stream. The 100 Gbit/s MAC supports 100 Gbit/s Ethernet. The 40 Gbit/s MAC supports 40 Gbit/s Ethernet. The 10 Gbit/s / 25 Gbit/s MAC supports 25 Gbit/s Ethernet and 10 Gbit/s Ethernet. The 10 Gbit/s MAC supports 10 Gbit/s Ethernet. The 1 Gbit/s / 10 Gbit/s MAC supports 10 Gbit/s Ethernet and 1 Gbit/s Ethernet.
Note: NT40A01 running on the 4 × 1 Gbit/s image only supports 1 Gbit/s Ethernet.

General operation

The 100 Gbit/s MAC, the 40 Gbit/s MAC, the 10 Gbit/s / 25 Gbit/s MAC, the 10 Gbit/s MAC and the 1 Gbit/s / 10 Gbit/s MAC are based on the IEEE 802.3 standard, and are optimized for line-speed throughput for receive and transmit operations used in the SmartNICs.

Link state

The current state of the Ethernet link is indicated in the NtInfoPort_s data structure (see DN-0449), and linkDownCounter (see Port Counters) counts the number of times the link has been down.

Length handling

The Ethernet frame length, without preamble/SFD but including CRC, determines MAC handling as:

  • Length < 64 bytes: The frame is discarded, and counted as discarded in a MAC counter.
    Note: The discard size can be configured using the DiscardSize parameter in the ntservice.ini file (see DN-0449).
  • Length > 10,000 bytes: The frame is hard-sliced to 10,000 bytes, and forwarded with a hard-slice indication.

    The wire length retrieved from the standard packet descriptor using the NT_NET_GET_PKT_WIRE_LENGTH macro (see DN-0449) is 10,000 bytes.

Error handling

Different kind of errors can occur for an Ethernet frame, and the handling of these is:

  • Code violation (CV) error: If illegal codes are received from the PHY, the frame is forwarded with a CV error.
  • CRC error: The Ethernet frame CRC is verified, and if a CRC error is detected, the frame is forwarded with a CRC error.

Frame forward format

Received Ethernet frames are forwarded by the MAC without the preamble/SFD but with the CRC.