How 4-tuple Hash Based Steering Works

In 4-tuple hash based steering, as implemented with the AD385A, there is no need for a lookup table. The driver and card steer all packets based on a hash value, calculated using the packet's source port, destination port, source IP, and destination IP. With this approach, all 8 queues are used evenly. It is applicable to both TCP and UDP.

4-tuple hash based steering requires NOSYNC patches. If NOSYNC patches are in the kernel, the default steering configuration is port based when the driver is up. Consequently, when NOSYNC patches are in the kernel, 4-tuple hash based steering has to be turned on and off manually.