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- [Instructor] Let's briefly talk about

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software defined networking.

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Software defined networking, or SDN,

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is a type of centralized
network management

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that is dynamic and programmable.

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It separates the data that is transmitted

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by network devices from the
administration of those devices.

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This can be helpful in a network

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that has many switches and routers.

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SDN is used to aid with
traffic engineering,

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routing, switching, monitoring,

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load balancing, and security.

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In a network that uses SDN,

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there is a separate system
known as a controller,

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and this talks to all
the routers and switches

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and other network devices.

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The SDN is broken down into two sections,

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the data plane and the control plane.

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The data plane is this black
arrow that you see here,

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and that is where the
packets are flowing through,

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and flowing through the
various network devices.

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Switches, routers, and so on.

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Those packets can be manipulated
by the SDN controller.

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And the SDN controller does this

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by way of the control plane.

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These dotted lines
represent the control plane

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to each of these network devices.

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This could be done on a separate network

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and it allows for the separation
of data and administration.

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Ultimately, the SDN approach

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deals less with individual
protocols on individual devices

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and more with the SDN
controller's instructions

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that are sent to those devices.

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The controller tells routers
and switches what to do

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with particular types of packets,

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applying rules as set by the
admin of that controller.

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So the administrator of the
controller sets the rules.

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For example, an admin might set a rule

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for a switch that has
a specific IP address.

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Perhaps this switch over here

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has the IP address 10.0.0.1.

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This is known as a match.

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And the admin on that SDN controller

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might state that there is a rule

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saying that this switch should drop

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a certain type of packet.

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So, maybe it says drop all ICMP packets.

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So any types of ping commands,
ICMP echoes or replies,

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are gonna be dropped from
that particular switch.

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So the rule specifies that
certain packets are dropped.

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This is the action taken.

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And this eliminates that type
of packet from being forwarded

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by that switch.

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You can also use SDN software
to more efficiently control

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large numbers of virtual machines,

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and categorize them within virtual LANs,

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allowing them to be grouped
and administered easily

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even if they're physically moved.

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And this makes the network more agile.

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The most commonly known SDN protocol

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is the open flow protocol,

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which is open source,
meaning anyone can use it,

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although companies such as
Cisco have entered the market

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with their own proprietary SDN solutions.

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Remember that in SDN,
there is a controller,

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a server or a virtual machine,
or perhaps a container,

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and that controller manages
your various network devices,

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routers, switches, and so on.

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Know also that there is a control plane

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and that is the network
connections for the management

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of those network devices to
and from the SDN controller.

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And then the actual data plane,

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which is where the actual
packets of data are being sent.

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All the other data on the network.

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And ultimately the SDN allows
for the efficient transmission

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of data packets.