GTM + LTM-VS+Irule and dynamic failover

Hi Qasim,

It would help if you gave some more information on how your iRule works, are you able to share it?

Lee

You could customise your health monitor on GTM to mark the server down if it receives a certain response such as "ERROR" or status code of 503. Then Modify your iRule to something like this

when HTTP_REQUEST {
    switch -glob [HTTP::host] {
        "abc.com" {
            if {[active_members INT_RTL_abc_8094_POOL] > 0} {
                pool INT_RTL_abc_8094_POOL
            } else {
                HTTP::respond 503 content "ERROR"
            }
        }
        "def.com " {
            if {[active_members INT_RTL_def_9443_POOL] > 0} {
                pool INT_RTL_def_9443_POOL
            } else {
                HTTP::respond 503 content "ERROR"
            }
        }
    }
}

It would mark the virtual server down that the iRule is applied to. So if one pool member is down, it would mark it down for all pool members at a particular site. There's no easy way of getting round this if you are sharing a single virtual server for different services.

With regards to the response codes, they don't really matter, it just something I added as 503 is a 'Service Unavailable' error so could be an appropriate error code.

You would still need to configure the health monitor on GTM to mark the service down depending on how you configure your VS to respond on service down.

here is the example of the rule:

when HTTP_REQUEST {

  switch -glob [HTTP::host] {

   abc.com         { pool INT_RTL_abc_8094_POOL }

   def.com         { pool INT_RTL_def_9443_POOL }     

  }

}

basically as there is no default pool so the VS don't go down if one of the Pool is down and as result GTM doesn't detect any change therefore no failover. Is there a way around this?

Kind regards,

thanks Lee, this is highly appreciated. so based on this if all the servers in the pool return http error code 503, the relevant VS will go down hence will force GTM to change W-IP. if so, can I add more error codes to this rule? how would it look like with another error code e.g. 403?

Regards,

 Hi Lee,

I hope you are well? I have used the above Irule and it has been working OK however I have come across a minor problem and was wondering if you will be able to help?

I want to use the IRULE now for a service that needs presenting externally as well and the LTM is local to the GTM i.e. same box.

using your IRULE I can track the LTM side VS and if theLTM pool is down and basically marks the GTM pool as down which is as expected however, I cant use the same monitor for Translation VS in GSLB and as the LTM VS status is always unknown the failover will not happen for a public IP.

Wondering if there is anything I can do track the status of LTM VS from the Transaltion VS in GSLB or the GSLB pool for the translation VS?

I hope the above make sense but let me know if you have any questions?

your help will be highly appreciated.

Regards,

Qasim