Questions on Load Balancer: How next available node (IP) will be chosen?

[ciscomdsmagic]

I am not sure if this is the right place to ask the question.

Assuming I have a F5 load balancer, and there are 4 nodes behind the load balancer, if one node got failed, how will then next available IP will be chosen?

Will there be a pool like which contains all 4 IP's, then the balancer will pick up the others in the pool, or is it more like a floating IP, then the floating IP will be pointing to the other IP, if one IP got disconnected?

Thanks!

[Jon Marshall]

This is a general answer rather than a specific one for F5 but usually you have a VIP (virtual IP) that users would connect to and tied to that VIP are the physical IPs of the devices behind the load balancer. 

The load balancer will then use all the physical servers to spread the load eg. a request from one user would go to the first physical server, the next request to the next physical server etc. 

In addition the load balancer will also send health probes to the physical servers so if one fails it is removed from the pool of available servers so requests are no longer sent to it. 

That is a fairly simplistic explanation, there are types of load balancing algorithms that can be used etc. but it covers the basic idea.

Jon