Accton Technology EN1407-SX manual Link Parameters, Packet Propulsion

Cheetah Gigabit Adapter

Link Parameters

The network card’s link speed, PHY type (physical connection to the network) and duplex mode can all be set from this page. However, if the “AutoNegotiate Link Parameters” box is checked these parameters are automatically determined and the configuration options greyed out. For most Gigabit Ethernet devices it is recommended to use Auto-Negotiation to set the link parameters. (Note that the adapter’s link speed can only be 1000Mbps and the PHY type is always G/MII.)

Packet Propulsion

The Packet Propulsion configuration option sets the packet- size threshold at which Propulsion technology is used to burst packets across the PCI bus. Propulsion increases the throughput of small packets by coalescing transfers across the PCI bus. This minimizes host CPU interrupts and bus arbitrations.

Use the slider control or edit box to set the packet-size threshold level in bytes (from 0 to 1514, or 9014 if Jumbo Frames is selected). Packets of sizes below this threshold use the Propulsion technique, packets above use the normal scatter-gather method.

There is a trade off between the Packet Propulsion and scatter-gather methods. Packet Propulsion uses more bus resources whereas scatter-gather uses more CPU resources. The optimum setting of the threshold level for a particular environment depends on various factors, such as

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