Why Load balancer

A load balancer is a device that acts as a reverse proxy and distributes network or application traffic across a number of servers. Load balancers are used to increase capacity (concurrent users) and reliability of applications. They improve the overall performance of applications by decreasing the burden on servers associated with managing and maintaining application and network sessions, as well as by performing application-specific tasks.

Load balancers are generally grouped into two categories: Layer 4 and Layer 7. Layer 4 load balancers act upon data found in network and transport layer protocols (IP, TCP, FTP, UDP). Layer 7 load balancers distribute requests based upon data found in application layer protocols such as HTTP.

Requests are received by both types of load balancers and they are distributed to a particular server based on a configured algorithm. Some industry standard algorithms are:

• Round robin
• Weighted round robin
• Least connections
• Least response time
• ADC can also divide traffic based on least number connections or we can say that we can forward request to the “least busy” server.
• conclusion is:

1.F5 can direct or redirect specific request to appropriate resources.

For example server 1 and server 2 has 100 requests and server 3 has 50 requests.

2.ADC Can intercept, inspect, and transform request or response and deliver it into the appropriate resources.

For Ex:-

HTTP is for the example application we can intercept, inspect, direct or redirect specific request to appropriate resources.

3.ADC can also divide traffic based on the sequence request coming in.

For example first request is for server 1 and second request for server 2 and third request is for server 3. It is called round robin fashion

4.Intercept, inspect and or transform request and or responses.

5.Verify health of back end server( will not send request to the server that is not up).


For more details:
https://devcentral.f5.com/s/articles/what-is-load-balancing-24740