What can we do when load balancer becomes the bottleneck?

Question

I just started learning load balancers. Taking a server side application (http/https) load balancer as an example, I assume it listens a specific ip address, then forward the http requests to available servers based on its algorithm.

So is it possible for a load balancer to become a bottleneck? Because it's listening a specific ip address, all requests will first go to the single load balancer. So I think there could be a scenario where the amount of traffic is beyond the limit/capacity of the load balancer.

When it becomes a bottleneck, what can we do? Can we use multiple load balancers?

I think one possible solution is to use multiple load balancers and expose all the ips to clients. (This sounds like client side load balancing) So when a client wants to send a request, it can pick from the ip pool and then send a request to one of the load balancers. (For example, ZooKeeper could be used here.) Is this a working solution? Is there any other way to use multiple load balancers?

Thanks. Ethan

Answer 1

Your last suggestion works with adding a little twist: The usual approach is to publish the load balancer IP addresses under the same domain name.

This is called DNS load balancing. Clients will ask for the IP resolution for your load balancer's domain name and they will get different IP addresses on a round-robin fashion.

To configure DNS load balancing you have to add multiple A records for your load balancer's domain name to your DNS configuration. Here you can find an example guide for that.