The loadbalance and LACP runners uses hashes of packets to sort network traffic flow. The hash computation mechanism is based on the
Berkeley Packet Filter (
BPF) code. The BPF code is used to generate a hash rather than make a policy decision for outgoing packets. The hash length is 8 bits giving 256 variants. This means many different
socket buffers (
SKB) can have the same hash and therefore pass traffic over the same link. The use of a short hash is a quick way to sort traffic into different streams for the purposes of load balancing across multiple links. In static mode, the hash is only used to decide out of which port the traffic should be sent. In active mode, the runner will continually reassign hashes to different ports in an attempt to reach a perfect balance.