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- [Instructor] SDN
implementations have northbound

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and southbound APIs.

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So what is actually a
northbound and a southbound API?

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Basically, in an SDN architecture,

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a southbound API is used to communicate

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between the SDN controller

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and the switches or routers
within the infrastructures.

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These APIs can be open or preparatory.

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Cisco proxy provides detailed information

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about all the APIs that are
supported in different platforms

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in the DevNet website
or developer.cisco.com.

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I highly suggest for
you to become familiar

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with this website, and not only that,

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but they actually provide a
lot of different exercises

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and you know,

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study material that you can actually use

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for free from Cisco.

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And later throughout the course,

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you're gonna learn about
using different APIs to

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you know, perform different functions

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in networking devices as well.

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Now, south bound APIs
enable the SDN controller

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to dynamically make changes
based on real time demands,

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and also based on
scalability needs, right?

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Now, the OpenFlow and the Cisco OpFlex

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are examples that actually provide,

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or examples of
implementations that provide

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southbound API capabilities.

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Now, northbound APIs,
or SDN northbound APIs,

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are typically restful APIs
that are used to communicate

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between the SDN controller

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and the services and applications
running over the network.

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So, these northbound
APIs can actually be used

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for the orchestration and the automation

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of the network components to
align with the different needs

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of applications via SDN
network programmability.

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So in short,

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northbound APIs actually
are basically the link

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between the application
and the SDN controller.

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In modern environments,

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applications actually can
tell the networking devices

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whether it's a physical, you know,

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a system or a virtual
network device or appliance.

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What are the types of resources
that actually they need?

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And in turn, the SDN
solution can actually provide

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the necessary resources
to that application.

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Now, Cisco has a concept called
the intent-based networking,

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and in many different locations

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you may see northbound APIs referred

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to as intent based APIs.