30 days of training on NetScaler! Day 2: Global Server Load balancing

Hello, it is day 2.

We have a Data Centre(DC)! It’s located in <insert war-torn city>, and the rates were awesome when you signed up. Of course, with the power of hindsight, it is possible that the deal wasn’t what you were expecting.

I think they did me up like a kipper, the cruise missile strikes were not expected at all.

You sometimes forget the fragility of life.

No fear. We have decided to get another DC in Berlin. It is centrally located for the bulk of our markets. The only snag is that < insert war-torn city> can still offer some resources and Berlin will not be fully up to capacity for another two months.

We will need to come up with a way to share capacity between the two sites. What could we possibly do to achieve that?

It’s simple, you need NetScaler.

You have requested some training; things might be a bit hazy as there was a football game at the weekend and the team just didn’t turn up! Who would be a football supporter? ?Anyway, the plan is to offer some pointers on NetScaler, with a series on all things related to the appliance. The goal is to provide you with enough information to be actually dangerous when talking to a customer or client. The number of days is a bit of an arbitrary number, but I am prepared to give you 2 minutes of material, can I get 2 minutes of your time?

I spoke about Load balancing yesterday, today is all about Global Server Load balancing. GSLB for short. I’ll have you sprouting buzzwords in no time.

Honestly, what are you talking about?

When I talked about load balancing, there was something of an assumption that the workloads were all in one place. Typically, companies don’t just have one DC. They typically have several.

?Yikes! This sounds complicated. It isn’t really

GSLB is when you have a number of DCs, it gives you a way to send users to the closest point of presence (POP). As far as the user is concerned, they just accessed their application or web app.?The users don’t care if your DC went dark, they just need to access the service.

So what? What problem does it solve?

GSLB gives you a way to make a service span a country or be truly global, the users are unaware of how you do it, as the magic happens behind the scenes (DNS). This kind of setup allows you to look at using a simple URL for them to access the service irrespective of the country they are in.

Something like https://go.domain.com/

It’s a simple one to remember, based on what DCs are up, GSLB will send the users to the right place. In this case, the right place can be a collection of DCs located around Germany for example. Alternatively, the DCs could be scattered around the world.

Who would be interested in this?

Anyone who runs a network and needs the service to be super resilient between DCs. It is common for NetScaler to be added for something internet-facing, as it allows the admin to be confident that she/he can have their workloads keep going as things ‘happen’.

When GSLB is added too, there is an option to send the clients to another DC in your setup should the closest to them have a problem.

Where does NetScaler fit in?

NetScaler is typically in front of the service that you run, here it is doing its magic in front of a web tier with GSLB layered on top of the load-balancing service.

In this case, NetScaler works out all the details of the individual web servers, as covered in the Load balancing walk-through yesterday. Using GSLB it can now add:

1.????Which site is best placed to serve this new client request; the diagram shows two sites but you can have up to 32 sites in this setup.

2.????You can choose between Active-Active or Active-backup for how the sites are treated, remember this works in Realtime. This means that the appliance knows what site is best at any given moment.

3.????It can also look at the client and say, actually this site is closer to where you are right now, use that.

4.????Finally, it works in conjunction with ADM to provide stats on the user experience, so the admin always knows what is going down before it does.?

I’m going to the cloud baby! We, don’t need that legacy piece of equipment.

You do! GSLB will let you add in cloud providers and try them with your existing sites, this gives you a way to mix traffic from your existing DCs into the new Cloud DCs. You can then check the bill and say ‘HOW MUCH!’ and write it off as an option you might use for only certain types of workload. Cloud isn’t bad, you just need to be sure it is the best fit.

The other consideration is that GSLB gives you the option to have a cloud DR facility, it can scale out when you lose a DC, so careless, and scale down once things get back to normal.

Ok, what else?

It offers a number of ways of working with traffic.

You can also build tiers of services, in some cases the 32-site limit can be a problem. Using a parent-child topology allows for much larger deployments.

You can learn more here, thanks Dave & Stanley

Summary.

Global Server Load Balancing is another unsung hero of businesses everywhere, it is a perfect fit for running workloads in a mix of Public cloud, co-lo and on-prem too.

Ultimately, it is a killer capability that is enabled with NetScaler.

What’s not to like?