Now that we have our additional VPN server configured and deployed,
we can move on to the task of enabling load balancing.
Now, as I stated previously,
I recommend using an external load balancer for best performance,
but unfortunately,
covering all the configuration options for third‑party load
balancers out there is out of scope for this course.
However,
Windows Network Load Balancing is a viable
alternative to an external load balancer,
and it is easy to configure and costs nothing,
so we'll take a look at that now.
Before we get started, I want to talk about some of the requirements for NLB.
The first thing we need to do is install the NLB role,
and we need to do that on all of the servers in the
cluster prior to configuration.
Next,
we need to set aside an IP address for the virtual IP address. This is
going to be the IP address that we address the cluster as,
and this needs to be an IP address from the same subnet as
the dedicated IP address or the IP address that the VPN
servers are physically numbered into.
And then finally,
just a quick word about operating mode. Network Load Balancing
has a couple of different operating modes,
the most common are unicast and multicast.
And we recommend using a unicast wherever possible,
but sometimes we have to use multicast.
So,
unicast works well in physical environments. Oftentimes, when we work
in virtual environments, you'll have to switch to multicast mode just
because of the subtleties and nuances of virtual networking, and there
may be some additional configuration required to support multicast
mode. Specifically,
you may need to create static ARP entries on border routers or
firewalls to support that, so that's in a bit of an advanced
configuration. We're going to use unicast mode,
and when that works, it works well,
but you may have to use multicast mode in your environment depending on your particular hypervisor.