[Jedd]

Interesting, thanks. Hadn't considered this option before, and will do some more exploring, though I note on the IPVS page they say:

"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.

[nullwasamistake]

I may be wrong, but I think you can tell IPVS to schedule using tuple hash only using Direct Return mode, which means no stored state for connection tracking.

Edit: doesn't appear to be true, but it uses it's own "lightweight" connection tracking table so you can unload conntrack modules from kernel.

Realistically IPVS can probably route 40 gigabit of traffic per instance. Combine that with DNS round robin and maybe even multi-homing at the front and you could handle basically anything