- In the last decade,
there have been so many changes
and shifts in networking technologies.
Some of the changes
are due to the demand of modern applications,
right,
especially applications that are now hosted
in many different environments,
not only in a data center
but in many different cloud environments.
So this complexity introduces risks
including network configuration errors
and also network security challenges,
right?
Subsequently,
networking functions like routing
and optimization and security also have changed.
And the next generation of hardware and software components
in the enterprise need to support this rapid introduction
and evolution of new technologies and solutions.
So this network infrastructure,
you know
must keep pace with the business environment
and support modern capabilities
that will actually, at the end of the day,
help drive simplification within the network.
So these elements have helped with the creation
of a concept called Software Defined Networking
and SDN,
you know,
or Software Defined Networking
was actually originally created to decouple control
from the forwarding functions in the networking equipment.
And this is actually done
to use software,
basically,
to centrally manage and program
this concept of programmability,
right,
and you know
manage and program the hardware
and virtual networking appliances
to actually perform,
you know,
network forwarding
and routing and network functions.
Now,
traditional routing and switching,
you know
have actually addressed three different planes.
You actually have the Management Plane,
where you have configuration and monitoring,
typically done via,
you know,
a CLI or GUI and each vendor
actually has their own proprietary way
to configure the devices.
And then you have Control Plane
and that's actually involves layer 2 and layer 3 protocols,
you know
and things like routing protocols, like OSPF, RIP, BGP
and et cetera.
Now you also have the Data Plane
and that's where,
or you know,
how data is actually forwarded inside of the hardware
from interface to interface
and from device to device.
So in SDN,
we introduce the notion of a centralized controller
and that SDN controller,
has actually a global view of the network
and it uses common management protocols
to configure the network infrastructure devices.
Right?
It also can use things like,
you know
restful APIs
to provide configuration
and streaming services,
to obtain telemetry
from the network devices as well.
Now the SDN controller
can also calculate
the reach-ability information
from many systems in the network
and pushes a lot of set of flows inside switches
and networking gear.
Now there are many different examples of open source
and commercial implementations of SDN controllers.
Now an example is the Open vSwitch OVS
and it's a project using a database called the OVS database
or OVS DB for the management of,
you know
the networking devices or network virtual devices as well.
Now the other one is Open Flow...
the Open Flow Protocol.
And you're gonna be learning a lot more
about that later in the course,
but I want to
also give you somewhat of a preview
of yet another example
but in this case it's actually a commercial
and Cisco's,
you know
implementation of an SDN controller,
which is
the Cisco Application Policy Infrastructure Controller
or Cisco APIC,
right?
And APIC is the main architectural component
or you can call it the brains
of the Cisco Application Centric Infrastructure
or ACI solution.
And those are actually great examples.
And you're gonna be learning a lot more about them,
later in the course.
You're also gonna be learning
about the differences between Northbound
and Southbound APIs
in the SDN architecture,
and then you know
also about other implementations
like the Cisco DNA and the Cisco DNA center.