Question about round robin

[Miroslav Lachman]

Kevin wrote:
> I am curious about simple round robin load balancing w/ PF. I see how simple
> it is to setup within the FreeBSD configuration file, but have a fairly
> simple question.
>
> Does PF detect if one of the addresses in the "pool" is not responsive? Or
> does it just blindly send traffic to all the addresses in the pool
> regardless? Is there some sort of heartbeat functionality or status check
> perhaps? Has anyone accomplished something along these lines? Load balancing
> would be pretty useless if I couldn't take a server out of the pool without
> having to re-configure PF every time.

"The round-robin method will accept multiple individual addresses using 
a list or table."

Tables are easily maintained by external applications / scripts - you 
can update theme without reloading of the rules. So you can write some 
little daemon pinging all your hosts and drop IP of unresponsive host 
from the table.
Or you can write some complex system to monitor hosts resources (CPU 
load, free memory, disk IO, etc.) and maintain content of the table by 
this criteria so you can get balancing based on real server load.

Miroslav Lachman