Load balancer
A load balancer is a device sitting between clients and servers. Its main purpose is to ensure the charge is appropriately balanced between every server, to avoid overcooking servers.
They operate either at layer 4 (TCP, IP...) or at layer 7 (HTTP...).
➡️ There are hardware-based and software-based load balancers.
They commonly use algorithms such as round-robin (in turn), weighted round robin (is server busy?), least connections/response time...
There are periodic checks to ensure that servers are still available. If there is no response from a server, it's considered as down. When the server is "up" again, it notifies the load balancer.
👻 To-do 👻
Stuff that I found, but never read/used yet.
- AWS Elastic Load Balancing
- HAProxy
- F5 BIG-IP
- Apache Traffic Server