Forum Discussion
AJ_Fasano_1976
Nimbostratus
NimbostratusGTM iRule. Is this possible?
First, I am not asking for the iRule. I would actually like to figure it out myself, assuming they are flexible enough for this.
We need a hybrid topology/RTT type of solution because of iss...
From my perspective, there are 2 problems with this plan. First, a good set of topology records shouldn't miss any LDNSs. That being said, if you want to "miss" some and use RTT to load balance them, there's something else that sounds iffy. The first time a LDNS sends a probe, GTM cannot use RTT as a load balancing metric. You mention waiting for the probes to return .. how long? If it takes 15 - 20 seconds to get the metrics (and that would be fast), the DNS resolution will take 15 - 20 seconds. That's a very long time.
Maybe I don't understand your goal, but you might be able to accomplish what you want without iRules (oops ...shouldn't say that on devCentral!).
If you used topology as the primary load balancing method in the pool, RTT as the alternative (when the topology record doesn't exist) and sometime else, even round robin as the fallback, you might get what you want. Queries from LDNSs that match topology records are decided that way. Returning LDNS's that aren't in topology records use RTT. New LDNS's (or those that don't respond to probes) use round robin - without a long wait.
Good luck!
