Difference Between TCP Load Balancer and HTTP Load Balancer and when to use what?

Question

I am trying to understand fundamental use cases between these two and when to prefer one over the other.

1. For example HAProxy support TCP load balancing. In practical cases when this would be a deciding factor?
2. Also What HTTP LB can achieve TCP can not and vice versa
3. Any reference architecture

Any relevant link with practical use case example would be great

Answer 1

1. For example HAProxy support TCP load balancing. In practical cases when this would be a deciding factor?

You would probably use this if you are using sockets/comet/full-duplex

2. Also What HTTP LB can achieve TCP can not and vice versa

Currently HAproxy is the most reliable LB on the market for TCP and websockets.

3. Any reference architecture

This would give you a start http://highscalability.com/blog/2014/8/11/the-easy-way-of-building-a-growing-startup-architecture-usin.html

Answer 2

TCP load balancing is pretty simple and yet powerful, it can be implemented at layer 4 (LVS) or layer 7 (HAProxy). An HTTP load balancer is a reverse proxy that can perform extra actions on http traffic, i.e. re-write sections of the traffic and inserting cookies etc. You only need a HTTP if you need one and if you don't you don't. (I'm sure that sentence almost makes sense).