Forum Discussion
Leo_D_53884
Nimbostratus
NimbostratusGTM iRule for Data Center Selection
All,
I have an interesting scenario, two data centers, NY with 1 GTM, 1 LTM cluster and Tokyo with no GTMs, 1 LTM cluster. I have different public IPs at each data center that are NATed to each LTM VS private IP. Since the GTM responded to DNS queries with the LTM VS private IP I wrote an iRule to respond with the Public IP address. What I would like to do is improve on the iRule so when NYC VS NYC-HTTP-VS goes down my iRule will respond with 1.1.2.10 the Tokyo public address.
NYC Data Center
Public IP 1.1.1.10 NATed to 10.10.20.5
LTM HTTP Virtual Server NYC-HTTP-VS is 10.10.20.5
LTM HTTP Pool HTTP-POOL
GTM iRule
when DNS_REQUEST {
if { [DNS::rrname] eq "www.wip.leo-d.com" } {
host 1.1.1.10
}
}
Tokyo Data Center
Public IP is 1.1.2.10 NATed to 10.10.30.5
LTM HTTP Virtual Server TKY-HTTP-VS is 10.10.30.5
LTM HTTP Pool HTTP-POOL
No GTM at this site
I have looked at the Jason Rahms post on new GTM iRules and it gets me in the ball park but I still am not sure.
https://devcentral.f5.com/tech-tips/articles/v10-new-gtm-irules-commands.UQLHD-z_Fog
I also looked at Colin Walkers post and am wondering if I should handle this some how with a CNAME redirect. Bottom line I am looking to trigger an action (new host IP) on an event (VS is down (GTM Pool member is down)).
https://devcentral.f5.com/tech-tips/articles/gtm-and-irules-allowing-intelligent-redirection-for-most-protocols.UQLHeOz_Fog
Sorry for the novel, any advise appreciated!
leo
2 Replies
- The_BhattmanHi Leo,
If I am reading this correctly, then you should also monitor the Tokyo LTM via the GTM pool
Then you could then re-write the irule as the following:
when DNS_REQUEST {
if { [active_members pool_tokyo] == 0 } {
host 1.1.2.10
} else {
if { [DNS::rrname] eq "www.wip.leo-d.com" } {
host 1.1.1.10
}
}
}
I haven't tested this out but hopefully this works for you
=Bhattman= 
Leo_D_53884Bhattman,
Actually I started to test this and realized that I need to look at the members of the pool. The pool HTTP-POOL would have two members NYC-HTTP-VS and TKY-HTTP-VS. What I am trying to do is trigger a response dependent on the status of the pool member. For example, when NYC-HTTP-VS is not available then I would direct traffic to Tokyo via the host 1.1.2.10 IP. If pool member NYC-HTTP-VS is available then I would like to direct traffic to NY via the host 1.1.1.10. The part I need help with is determining when the pool member, TKY-HTTP-VS is down. Thanks a bunch.leo
