The advent of cloud computing has changed
networking in many ways.
And if you're a network administrator,
you know that in the cloud, we don't usually
have physical routers, switches, and other infrastructure
devices.
Instead we need to take these networking platforms we
use in the real world and move them
into the virtualized cloud based world.
One way that we're able to do this
is through the advent of Software Defined
Networking or SDN.
With software defined networking,
we take those devices like switches, routers, firewalls
and other networking infrastructure devices
and we change them to be a software based platform
that we could use in the cloud.
This means that we might take something like a switch
and separate all of the functions of the switch
into individual pieces.
We can then take these pieces and then create
software versions that we can then run in the cloud.
There are commonly three layers or three ways
to separate these devices so that we
can create some consistency across all of these networking
components.
The first layer would be the infrastructure layer.
Sometimes we hear this referred to as the data
plane of that device.
So it's common that this data plane
would do the forwarding, the trunking, the encrypting,
the network address translation, or anything else that needs
to occur at that packet level.
When our routers and switches need to forward this traffic
in the data plane, they need some type of reference
to know where this traffic will be going.
Most of those references will be in the control layer or control
plane of that device.
So if you have dynamic routing protocols,
a forwarding table in a switch, a network address translation
table in a router, all of those are
contained in the control plane.
And of course, you or some other process
is in charge of managing that device.
To be able to manage it, we need to log in or access
the device via an API or Application Programming
Interface.
And all of that access is provided
at the application layer or management
plane of that device.
So when you SSH into a router, when you bring up
a graphical front end of a firewall,
you're managing that device from the management plane.
Let's see how this software defined networking would
apply to a physical device.
And in this case, this physical device appears to be a switch,
but this could be a router or firewall
or any other infrastructure device.
Let's start first with that infrastructure layer
or the data plane.
If you're connecting to a switch or you need traffic
forwarded between different interfaces on a switch,
that all occurs in that data plane.
This means we'll take anything that
may be forwarding this traffic on that device
and create a software version of that
that we call the data plane.
These devices also need the tables and forwarding structure
to be able to understand where traffic is coming from
and where you'll be forwarding it to,
and all that occurs in the control layer or the control
plane.
And lastly, you'll be managing this device probably
through a console port or management
interface to the device, and that section of the device
can be created as the management plane.
Obviously with software defined networking,
there is no physical device, but you
can see where the data plane, control plane, and management
plane are pulled from our physical devices
to create this software based networking infrastructure.
This now creates modular layers that you
can extend between devices or create new devices all based
on the software defined networking.
If we start, for instance, at the bottom,
we know that network traffic will
be traversing different devices all at the data plane.
So communication between those can occur solely
between those particular layers.
A device may need to send or receive
dynamic routing protocols or create tables for forwarding,
and all of those can be done at the control
layer or the control plane of software defined networking.
And the layer that you're going to manage these devices from
will be the management plane.
We usually access the management plane
through secure shell, simple network management protocol,
or an application programming interface.
You can see that the software defined
networking takes these very standard categorizations
and extends them across multiple networking devices
to create a very modular architecture.
This allows you to have a software based version
of these network devices that we use on our physical networks
and be able to deploy them and use them in a cloud based
infrastructure.