We'd like to explore a private network so we can get away with more than 64k per client, as it starts to get expensive spinning up 50 servers whenever we want to test. Unfortunately, the instances that were lent to us came with no way for us to assign additional IPs.
You don't need multiple IPs, tcp connections are a unique 4-tuple: {ClientIP, ServerIP, ClientPort, ServerPort}. If you add more ServerPorts, you can re-use the client ports. Now, if you want to test past 4 billion connections, you need more IPs. :)
> You don't need multiple IPs, tcp connections are a unique 4-tuple: {ClientIP, ServerIP, ClientPort, ServerPort}.
Sometimes someone throws something out so casually and yet you realise the innate sense of what they just said, I literally stopped with coffee halfway to my mouth.
I may have connection tested a few things in the past ;) If you're benchmarking with tsung, it's nice, because it has hooks to let you pick the client port when making the connection; you'll probably need this, because the OS default assignment algorithms tend to get it wrong with this much stuff going on.
Wait wait wait, you can re-use client ports for multiple connections? Does this actually make it past NATs? Why does every TCP connection get a unique client port by default if there's no problem with reusing them as long as you're talking to a different {ServerIP,ServerPort} pair?
