F5 - GTM (Global Traffic Manager) DNS

F5 Global Traffic Manager (GTM) is a DNS-based load balancing solution that provides global server load balancing and traffic management across multiple data centers or multiple nodes to improve application availability and performance.

Here’s the current topology of my lab

F1 and F2 are linux servers serving web on port 80 (http)

The plan is to load balance the web request coming to these 2 servers using GTM (Global Traffic Manager) with DNS GSLB (Global Server Load Balancing). Let’s start!

Create DNS Listener on F5

The domain that i have on my lab is helena.gg, and here on F5 i will set it as a nameserver to handle all the DNS query requests for the delegated subdomain of lab.helena.gg

To set it up, go to DNS » Delivery » Listener, and create new

Give it a name and an IP Address

Create Datacenter

Next creata a Datacenter, because my topology only spans inside one datacenter, i’ll only create one.
To create, Go to GSLB » Data Centers » Data Center List

Create Server List

After that let’s create the server list, go to DNS » GSLB » Server Lists.

The first server list is named GTM, this list will contain all the IP Address of GTM’s external and internal interfaces

The second one is the list server containing the linux servers where the webs are hosted

And this is the server lists that i end up with

Create Server Pool

Next let’s create the server pool containing the linux web servers.
Go to GSLB » Pools » Pool Lists

Create Wide IP List

Lastly, create the Wide IP FQDN that will be hit by the DNS Server containing the pool that has just been created

And this everything should light green indicating the web servers are reachable.

That’s pretty much it for the configuration on the F5 side, now proceed to the DNS Server, which in my case is on my Active Directory Domain Controller

Delegate the Subdomain on DNS Server

On the DNS Manager, create a new Name Server Rntry that points to the F5 DNS Listener

Then create a delegation subdomain, which will be subdomain “lab.helena.gg”

Then add the newly created nameserver entry as this subdomain’s name server

Lastly, create a CNAME record that points to FQDN subdomain that exist on F5 Wide IP configuration

And that’s pretty much it. Let’s test it

Test the GTM

Pinging the f.helena.gg will give an alternating resolved IP between F1 and F2 servers, because the load balancing algorithm is set to round robin.

Same goes if it’s being hit on the port 80 using web browser

Going to Module Statistics, it shows the counter of how many times it has been hit