Issue 11
© Solarflare Communications 2014
138
Solarflare Server Adapter
User Guide
Checksum Offload
Checksum offloading is supported on IP, TCP and UDP packets. Before transmitting a packet, a
checksum is generated and appended to the packet. At the receiving end, the same checksum
calculation is performed against the received packet. By offloading the checksum process to the
network adapter, the load is decreased on the server CPU.
By default, Solarflare adapters are set up to offload both the calculation and verification of TCP, IP
and UDP checksums. The following Checksum Offload options are supported:
You can also configure Checksum offload settings from the network adapter properties. See
Configuring Network Adapter Properties in Windows on page 167
for more details.
Table 32: Checksum Offloads
Check box
selected
Transmit and Receive
Transmit checksums are generated and
received checksums are enabled. This is the
default setting.
Check selected
but selection
greyed out
Transmit Only or Receive
Only
For either transmit or received checksum
only.
NOTE:
The Transmit or Receive Only states
can only be set from the Advanced tab of
the Driver Properties. See
Network Adapter Properties in Windows
on page 167
for more details.
Check box
cleared
Disabled
Disabled. Data will be checksummed by the
host processor for both transmitted and
received data.
NOTE:
Changing the checksum offload settings can impact the performance of the adapter.
Solarflare recommend that these remain at the default values. Disabling checksum offload
disables TCP segmentation offload.