Recreating a Node Status Dependent Round Robbin DNS effect with F5

This can be done on LTM using HTTP monitors. If there's a special page to check for status (/amiupordown.html for example), you can tailor your HTTP monitor receive string to determine whether to mark the node up or down based on the content of the page.

This will allow the farm admin to control which server to activate with no changes required on the LTM.

Yes, I agree with you, HTTP monitors can monitor specific keywords within a monitored html page. However it's only a part of the solution I am seeking as my client application needs to establish a connection directly with the node, not with the virtual server.

My apologies, I see you are looking specifically for DNS load balancing and no proxy.

You can setup GTM to use an HTTP monitor to do this. Your two nodes would be members of a GTM pool and would be assigned to a wide IP. GTM would respond back to the client's request with whichever node is active at the time, based on the custom HTTP monitor you build.

Thanks. In my active modules when looking at my licenses within F5 admin gui, I have the following, but do not know how to interpret it :

License Type Production

GTM-DNS, Rate Limited, LO, BIG-IP(Perpetual)

DNS Rate Fallback, 50 GTM Rate Fallback, 8 DNS Licensed Objects, 0 GTM Rate, 8 DNS Rate Limit, 50 QPS GTM Licensed Objects, 0 Optional Modules ..... Global Traffic Manager Module

Would that mean I could technically realize the solution you just mentioned above (e.g. setup GTM to use an HTTP monitor) with this license profile?

Looks like you may have some limitations as far as objects, but you have the Global Traffic Manager module license which is the requirement to do this.

To test, create your two servers (Global Traffic -> Servers) first. Then create the pool (Global Traffic -> Pools) and assign the two servers you created. Don't worry about a monitor for now. Then create a wide IP (Global Traffic -> Wide IPs) and assign the pool you just created.

If this all can be done, then you should be good to go. You'll just need to build that custom HTTP monitor with the appropriate send and receive strings.

Ok thank you. The F5 11.4.1 box in which I would like to try to implement this solution shows that the GTM is "licensed" but is not enabled under the provisioning column (it shows "none"). When just putting a check mark in the box, a drop down box appears allowing me to chose between "nominal" and "minimum". This box is the actual production box. My question is : can I simply turn on the GTM feature and update the box without adverse impacts of any sort? Can GTM, once installed, have all kind of unforeseen effects? Can it interfere with our virtual setups? I would like no risk at all, given it is a production box.

Thanks

I was told by a consultant that, out setup being in an active-passive pair (we have a pair of synchronized F5 boxes), implementing GTM to do DNS load balancing like the one we would like to implement here is not a good idea. Is it true? For what reason? In the case it would be true, are there workarounds? What are the pros? The cons?

Thanks