Load balancing between two datacenters

Scenario:

  • You have at least two datacenters running the same application and both datacenters are simultaneously active (business continuity)
  • Your application is mapped on a well-defined hostname (ie. www.myapplication.com)
  • On the  first datacenter www.myapplication.com is running on IP a.b.c.d. One the second datacenter www.myapplication.com is running on IP x.y.z.t
  • You need your clients traffic to be equally split between the two datacenters

Solution:

  • Use GSLB.me in round robin balancing mode
  • Define one geohost that will be pointed by www.myapplication.com via a DNS CNAME record
  • Create two targets, one for each datacenter
  • Assign the relevant checks to each target
  • Configure the CNAME record on the primary DNS server that handles the domain myapplication.com

How to configure it:

  1. Register on GSLB.me and log on
  2. Select under which one of the available domains (gslb.us, gslb.info, …) you want to create your geohost. You can choose the domain you prefer, this is purely a “cosmetic” choice. Let’s choose mywebsite.gslb.eu
  3. Create your geohost: a geohost is the FQDN (Fully Qualified Domain Name) that your authoritative DNS will use as a CNAME for your application hostname (ie. www.myapplication.com). Select “Round robin” as your balancing algorithm. This will enable active-active distribution of incoming traffic towards your datacenters
  4. Define the first target: the target’s IP address is a.b.c.d
  5. Select checks to be performed on the first target
  6. Define the second target: the target’s IP address is x.y.z.t
  7. Select checks to be performed on the second target
  8. Configure your authoritative DNS to use a CNAME record to have www.myapplication.com point to mywebsite.gslb.eu
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    Slide1
    Go to http://go.gslb.me and logon. If you still don't have an account you can register and then logon.
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    Slide2
    Once logged in let's create a sample geohost named mywebsite.gslb.eu. We can choose any top level domain among those shown on the left hand side of the GSLB.me interface.
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    Slide3
    Let's right click on the domain we choose in order to create a new geohost.
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    Slide4
    Next, we need to configure the geohost name (it will be prepended to the zone we selected in the previous step), set it to enable and select "Round Robin" as the balancing algorithm. We can configure DNS replies TTL from here. When done, let's click on "Save" to save changes.
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    Slide5
    After clicking on "Save" changes are committed and confirmation is displayed at the bottom of the screen.
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    Slide6
    After creating the geohost we need to add targets: a target is the IP address of our application at each datacenter we are going to load balance. Let's right click on the geohost name and add the target from the popup menu that appears.
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    Slide7
    Let's now configure the IP address of our target, which is the IP address our application runs on the given datacenter. Checks schedule time can be set and the list of healthchecks to be performed is also configured here. Once done let's save the changes.
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    Slide8
    After clicking on "Save" changes are committed and confirmation is displayed at the bottom of the screen.
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    Slide9
    Let's now configure the IP address of our second target, which is the IP address our application runs on on the given datacenter. Checks schedule time can be set and the list of healthchecks to be performed is also configured here. Once done, let's save the changes.
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    Slide10
    After clicking on "Save" changes are committed and confirmation is displayed at the bottom of the screen.
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    Slide11
    Now we completed our geohost and targets configuration. We need to commit this setup to make it active. To do so let's right click on the geohost name on the left hand side of the screen and commit the changes.
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    Slide12
    After committing changes a confirmation popup is displayed at the bottom of the screen.
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    Slide15
    We can now open the map to show our targets' geographical position and availability. Let's right click on the geohost name and open the map.
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    Slide16
    The map shows our targets positions and current availability. It is automatically refreshed every 5 seconds.
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    Slide17
    We can now open the status window to see the status of all geohosts and their targets. Let's right click on the geohost name and open the window.
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    Slide18
    The status window shows the health of our geohosts and targets. It is automatically refreshed every 5 seconds.
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    Slide13
    Let's now right click on the geohost name again to display the DNS entry we need to add to our authoritative DNS for the "myapplication.com" domain in this example.
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    Slide14
    In our example we will need to add to the "myapplication.com" DNS zone the entry "www.myapplication.com. 600 IN CNAME mywebsite.gslb.eu". This enables GSLB.me-based load balancing for your www.myapplication.com fully qualified domain name.
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