Load Balancing Building Blocks

The Reverse Proxy type of load balancer is probably the most common one - it is Good Enough for most applications. The differences between the L4 and L7 proxy variants come from which level of the OSI model they deal with. L4 load balancers deal with individual connection flows (think TCP/UDP packets, plain bytes), while L7 load balancers deal with individual requests (think HTTP requests, GETs or POSTs). In the proxy design, incoming connections are terminated on the load balancer, and the request passed on to one of the backend servers, either by opening a new connection or using an already established one....

This is a long form version of my talk at SRECon EMEA 2019 - Load Balancing Building Blocks. But it’s turned into a bit of a brain dump, writing down what I’ve learnt. My alternative title was “What I wish I knew about (Network) Load Balancing”. Why do we need Load Balancing? Load balancing essentially comes down to spreading requests across multiple servers. There are a few common reasons to do so:...