Learn F5 Technologies, Get Answers & Share Community Solutions Join DevCentral

Filter by:
  • Solution
  • Technology
Answers

GTM load balancing dilemma

I have an architecture where a GTM is load balancing a service between two data centres. The GTM uses iQuery to communicate with the LTMs in each data centre.

Now, the main Virtual Server on the LTMs passes traffic through some HTTP classes and ASM - but the key point is, the VS doesn't have a default pool specified for security. This means that the VS doesn't have a health status i.e. it is a blue square. This has implications on the GTM - it doesn't know if the VS is really there or not. What it can establish, however, is the number of connections to each VS and therefore intelligently load balance between the data centres.

What I have tried is to create a dummy Virtual Server that has a default pool containing the same web servers as the product VS, but listening on a dummy port. This doesn't affect the GTM of course because that only cares about the IP address. The problem now is that this method tells the GTM the availability of the data centre but NOT the number of connections!

Can anyone suggest a way of getting all the information at the GTM so that it is aware of both the connections and availability?

Thanks, Keith
0
Rate this Question

Answers to this Question

placeholder+image
USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER
If you virtual server is a single port, you could assign the bigip & tcp monitors at the virtual server level, then make sure the availability requirement is all health monitors.

0
placeholder+image
USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER
One other point...

If you have a "catch-all" HTTP class, with no filters that matches all requests, configured last in the class list, there isn't a chance that requests would be sent directly to the pool (and not go through ASM). I think the recommendation to not use a default pool on the virtual server is still applicable but not a requirement. With that being said, if you know a request will never make it to the default pool, it would be safe to configure one so that the virtual server state is reported accurately.

Aaron
0
placeholder+image
USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER
Have you tried creating a dependency in GTM, making primary VS availability dependent on dummy VS availability?
0
placeholder+image
USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER
No, I wasn't aware that was possible. Can you elaborate?

The GTM is a separate box to the LTM where the Virtual Server is hosted. Is it possible over iQuery to do this?

Thanks for the responses btw!
0
placeholder+image
USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER
It's an option that tells GTM to consider VS1 as available only if VS2 is also available. It's an option available in the GTM GUI, under Virtual Server definitions (change basic to advanced). I haven't used it to solve your particular problem myself, but I think it might do the trick for you. If it does work, let us know.
0
placeholder+image
USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER

Sorry to bump up an old thread but I have something similar today with 11.5.3.

To anyone's knowledge has any progress been made in how to deal with GTM checking LTM VS status when the LTM VS doesn't have a default pool.

THanks.

0