Load Balancer Limits

There is no general "limit" because it depends on how the load balancer is implemented and utilized (load balancing technique).

Performance parameters are

• Throughput
• Number of Retained Sessions
• encrypted throughput for SSL

There's something.

The top models can support over 10Gbps by specification, but before they get there, they usually have limitations on line throughput, applications, and so on, so they start using CDN to release traffic and distribute connections at the application level.This will reduce the load balancer burden.

As for road balancers, there are large and small (the price ranges from 400,000 yen to tens of millions of yen), so you have to check the catalog of each device.
For example, F5 companies that make load balancers called Big-IP.

It is common to set the limit slightly below the product limit, and to send it to another site when the limit is exceeded, or to display a rejection page such as "Currently crowded".

While each site is constantly monitoring access and providing equipment that can be accessed several times as well, any large site can reach its limit in the event of multiple failed load balancer devices or DDoS attacks.
　

What are the limits?

This is the data sheet of F5 Networks, the No. 1 LB industry share.
http://www.f5networks.co.jp/shared/pdf/BIG-IP-HW-Datasheet.pdf
Also, when Nginx or LVS is added to Linux and used as LB, performance per unit is usually much lower than hardware LB.
This is because the hardware LB has offload capabilities on ASICs and FPGA.

Also, what happens when the load balancer reaches its limit?

Scale up or scale out.
Depending on what resources you have reached their limits,
If it is a band, add a link, and if it is a CPU or memory, change the setting to a lower load.
NAT Configuration → DSR Configuration, L7 → L4, Stop Persistence, etc.

Is there no limit on Facebook or Twitter?

Here we go.
So it's being studied all over the world every day so that it doesn't reach its limit.
http://yunazuno.hatenablog.com/entry/2016/02/29/090001
This page is helpful in Japanese.