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GSLB Active/Active - Problem with the client connections


Gabriela Majic

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I have a problem in the configuration of active / active gslb, for applications that have a configuration file that refers to a gslb domain, in this case the result is that data centers are crossed, and this situation is not desired. What we need to implement is an active / active gslb where requests always remain in the same data center and I can also put persistence in balanced services. Can you give me recommendations for this implementation? Thank you

Gabriela

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Yep, Mihai is correct, you are looking at GSLB persistence to anchor your DNS resolution to a datacenter after the initial decision is made.  This will be eithe sourceip or cookie-based (which is kind of a deffered persistence decision). SourceIP is usually the easiest, but there may be other factors.

 

Once GSLB persistence is set to keep the DNS resoultions in the datacenter you original selected per dns lookup; you then rely on load balancing persistence at the LB vserver level for app specific requirements.

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Good afternoon

The persistence is maintained, what I need to implement is to be able to ensure that the dns always returns the ip of the gslb service according to one criterio. The firmware  del vpx is 12.0.69 The only documentation I have found is this.

https://docs.citrix.com/en-us/netscaler/12/global-server-load-balancing/how-to/manage-client-connections.html

 

But I can't make it work.

Someone could give me recommendations on the subject.

Thank you

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If you are doing active/active gslb, what are you basing the GSLB decision on?  sourceip/RTT, ip map or other datacenter performance metrics like least connections/least bandwidth?

What GSLB persistence did you implement?  sourceip (on the gslb vserver OR cookie insert which is configured on the GSLB services and should be propagated to gslb peers via MEP)?

 

You say that you want persistence (for GSLB) maintained based on one criteria, what criteria do you want it based on?

 

Remember: GSLB persistence only affects clients making the DNS lookup during the GSLB/DNS resolution phase.  It ensures that if the client does an additional GSLB lookup before the GSLB persistence expires we resolve them to the same destination IP (VIP) that their previous GSLB lookup resolved them to.  Once they hit the lb vserver, its controlled by load balancing.

 

When you say its not working, what is not working?  We need some additional details to assist you.

 

Once gslb persistence is enabled, if the test client:

1) flush dns cache

2) do a nslookup for <gslb fqdn>

3) Repeat nslookup... do you get the same IP for gslb or not (NOTE: this test will only show persistence if using source ip persistence)

If using GSLB cookie-insert, then you might get the alternate VIP returned, but when the client connects to datacenter 2's vip, the cookie persistence will result in them being redirected back to VIP1 (datacenter1) or proxied to datacenter1 depending on which persistence is in use.

 

Once you get them to the correct datacenter, then your regular load balancing persistence should be in the lb vserver.

 

 

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