Nice to see someone mention direct server return or as BigIP called it nPath routing. This was an effective scaling method for handling small request that returned large payloads (audio and video files). I don't know how well known this configure is or whether it is still viable in an all TLS world.
It doesn't seem particularly well known. It works fine with TLS, but the origin servers need to do the TLS termination (IMHO, this is better for security than having your load balancers do it, but it does mean you have to work harder on key distribution). On a non-DSR load balancer, doing TLS termination on the origins means the load balancer has less application data to work with (request path, response status code, etc) in making load balancing decisions, but for DSR, the load balancer never had any of that, so adding TLS doesn't disadvantage the load balancer any more.
TLS session establishment is expensive, so why would I want my load balancers to do it anyway? :P
Should you wish to give DSR load balancing a go without having to invest in hardware/licenses you could try https://github.com/davidcoles/vc5
Put that in front of some HAProxy servers to do TLS termination and farm out requests to another layer of NGINX/uWSGI boxes and Robert is your cousins father.
It kinda fell out of favour when even midrange server can do tens of gigabits of TLS traffic. So you need to be very big traffic wise to make it worth.
