supporting "ratio weight" in third party appliances

>iControl is our management API that is used to configure and pull statistics from our devices

 

 

Are you saying that iControl can not be used by 3rd party systems as an interface to F5 devices? I did recall reading a document on the iControl interface (SOAP based).

 

 

No I am not saying that. iControl is a clientside management API that is most typically used from management systems, not from backend servers (aside from pushing health statistics back into the servers). You wording implied that you needed to "implement" these interfaces, not "use" them. There is a big difference. iControl interfaces are not something you have to implement the code for (ie BIG-IP talking to your server), but rather ones that you use on the client side (your server talking to the BIG-IP).

 

 

>Now, if you want to use iControl to set your BIG-IP's configuration, then you can use the LocalLB::Pool::set_lb_method() and LocalLB::PoolMember::set_ratio() methods to update these properties.

 

 

May I understand that our applications running on our device need to support these two methods? If that's the case, it is great!

 

 

Your application only needs to access these methods on the BIG-IP if you need to dynamically update their containing pools load balancing algorithm or their individual load balancing ratios. Again, this typically isn't done in backend code, but rather from a configuration system.

 

 

>Your questions seem to imply that you need to do something in your backend servers to have them work in ratio mode and that is not the case. In iControl, there are no interfaces you need to implement (outside of the event notification interface for system messages) on your backend servers so I think you are all set.

 

 

I'm confused on this one. How does the Big-IP know the stress level of our servers? I understand that Big-IP does LB based on the stress level of the nodes.

 

 

BIG-IP determines how to route traffic based on the load balancing algorithm it's using. Round Robin is a very simple one after the other approach, while ratio allows you to assign weights to each server and traffic will be distributed based on those ratios. There are also least connections, fastest response, and a few others. I'd recommend hitting the BIG-IP LTM manual for more details on load balancing algorithms.

 

 

With that said, if you do want to make your system more dynamic in nature where the backend servers feed their "health" back into the network in real-time, then you would use the methods described above to dynamically change their "ratios" based on data you have on the backend server.

 

 

 

>As for the bridge mode question, BIG-IP just sees the backend connection as an ip address. Whether or not it's in bridge mode. If the address is up, traffic will be sent to it and if it's down traffic wont. So again, I don't see any issues.

 

 

Since bridge mode node does not have IP addresses, so I guess bridge mode is not supported

 

 

I don't believe there is an issue as the traffic is IP as it's going through the BIG-IP regardless of whether a device downstream is in bridge mode or not.

 

 

Hopefully this has cleared things up.

 

 

-Joe