"For scheduling UDP datagrams, IPVS load balancer records UDP datagram scheduling with configurable timeout, and the default UDP timeout is 300 seconds. Before UDP connection timeouts, all UDP datagrams from the same socket (protocol, ip address and port) will be directed to the same server."
I'm hopeful / confident that affinity can be fully de-tuned here, as we're looking at around 5-10k UDP Netflows per second from a given router that need to be distributed to a set of receivers.