Connecting HAproxy load-balancer to WAN and LAN

Your confusion is reasonable - they are often the same thing. But not always. When you refer to a load balancer you are referring to a very specific thing - a server or device that balances inbound requests across two or more web servers to spread the load. A reverse proxy, however, typically has any number of features:

1. load balancing: as discussed above

2. caching: it can cache content from the web server(s) behind it and thereby reduce the load on the web server(s) and return some static content back to the requester without having to get the data from the web server(s)

3. security: it can protect the web server(s) by preventing direct access from the internet; it might do this through simple means by just obfuscating the web server(s) or it may have some more active components that actually review inbound requests looking for malicious code

4. SSL acceleration: when SSL is used; it may serve as a termination point for those SSL sessions so that the workload of dealing with the encryption is offloaded from the web server(s)

I think this covers most of it but there are probably a few other features I've missed. Certainly it isn't uncommon to see a device or piece of software marketed as a load balancer/reverse proxy because the features are so commonly bundled together.

My understanding is that haproxy is a load balancer, the benefits of which are scaling and redundancy NOT performance.

To bench the effects of your load balancer you should run you should first bench the faster of your servers, increasing the load until you find the point at which it falls apart. Then start at that point when you bench haproxy, you should be able to handle approximately twice the amount of connections.

To increase the speed you want a caching reverse proxy such as nginx, varnish or squid.