Onload User Guide (UG1586)

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1.2 English

The CTPIO feature can be used in three modes:

  1. cut-through (ct)

    Lowest latency. A packet is transmitted onto the network as it is being streamed across the PCIe bus. The adapter starts transmitting the packet even before the entire packet has been delivered over the PCIe bus.

    Note: This mode is supported at 10 Gb, but not at 25 Gb.
  2. store-and-forward (sf)

    The packet is buffered on the adapter before transmitting onto the network. The adapter only transmits when the whole packet has been delivered over the PCIe bus.

  3. store-and-forward-with-poison-disabled (sf-np)

    As for [2], but guaranteed that packets are never poisoned. Invalid packets are not transmitted on the wire. This is the default mode for Onload.

When [3] (sf-np) is enabled on any VI, all VIs are placed into this mode.