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