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