Packet Propulsion; Jumbo Frame Support - SMC Networks EtherPower II 1000 User Manual

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. Depending on
your PC hardware and the applications you are running, you can
set the Packet Propulsion threshold to optimize the performance
of the EtherPower II 1000 card or its effect on your operating
system.

Jumbo Frame Support

The EtherPower II 1000 network card can be configured to use
Jumbo Frames. This increases the maximum Ethernet frame size
from 1514 bytes up to 9014 bytes. Using Jumbo Frames greatly
reduces the packet processing overhead for the host CPU and can
boost throughput by up to 300% for bulk data transfers.
Note that to use Jumbo Frames, both communicating computers
must have network cards that support this feature. Also, network
devices connecting the two computers must support Jumbo
Frames.
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