
Issue 11
© Solarflare Communications 2014
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Solarflare Server Adapter
User Guide
4.12 Segmentation Offload
Solarflare adapters offload the tasks of packet segmentation and reassembly to the adapter
hardware, reducing the CPU processing burden and improving performance.
LRO is a Solarflare proprietary mechanism similar to the Windows Receive Side Coalescing feature.
When enabled the adapter will coalesce multiple received TCP packets on a TCP connection into a
single call to the TCP/IP stack. This reduces CPU use and improves peak performance. However LRO
can increase latency and should not be used if a host is forwarding received packets from one
interface to another. LRO is disabled by default.
You can also configure LSO and LRO settings from the NDIS properties. See
Adapter Properties in Windows on page 167
for more details.
Ethernet Link Speed
Generally, it is neither necessary or desirable to configure the link speed of the adapter. The adapter
by default will negotiate the link speed dynamically, connecting at the maximum, supported speed.
However, if the adapter is unable to connect to the link partner, you may wish to try setting a fixed
link speed. For further information see ’Link Speed’ in
Ethernet flow control
Ethernet flow control allows two communicating devices to inform each other when they are being
overloaded by received data. This prevents one device from overwhelming the other device with
network packets. For instance, when a switch is unable to keep up with forwarding packets between
ports. Solarflare adapters allow flow control settings to be auto-negotiated with the link partner.
You can also configure ethernet flow control from the network adapter properties. See
for more details.