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In this section we will talk about Cisco software defined access model Cisco software defined access

creates an entirely new way to build campus local area networks as compared with data additional methods

of networking in the middle of 2000 and 10 Cisco set to about to array.

Imagine campus networking with software defined access as the result guys.

Software Defined access uses the software defined architectural module with EQ controller and various

AP eyes.

It still uses a physical network with switches and routers cables and various endpoints also at the

center.

Since the digital network architecture which is DNA Center controller with human users making use of

a graphical user interface and automation using API as in shard DNA center is the controller for software

defined access networks.

Architecturally the southbound side of the controller contains the fabric underlay and the overlay by

design.

SD and implementations most of the interesting new capabilities or care on the northbound side so let's

talk about the fabric underlay and the overlay terms which are the important terms for Cisco's software

defined access.

Let's start with the overlay overlay is the mechanisms to create weeks Len tunnels between software

defined access switches which are then used to transport traffic from one fabric end point to another

over the fabric underlay is the network of devices and connections to provide IP connectivity all nodes

in their fabric with a goal to support the dynamic discovery of all software defined access devices

and end points as a part of the process to create overlay.

We x land tunnels and when it comes to fabric fabric is the combination of the overlay and underlay

which together provide all features to deliver data across the network with the desired features and

attributes in less formal terms guys the underlay exists as a multilayer switches and they are links

with IP connectivity but for a special purpose the underlay supports some new concepts with at tunneling

method called weak land traffic sent by the end point to flows through weeks land tunnels in the overlay

a completely different process than through additional land switching and the IP routing for instance.

Think about the idea of sending packets from hosts on the left of a network over the software defined

access to hosts on the right of the network for instance guys let's imagine a packet enters on the left

side of the physical network and eventually exits the campus out of the switch that you can see in here

from switched to OK.

This underlying network looks like a more traditional network droving with several devices and links

right.

But when you check the figure at the top of the screen which is showing only two switches called Fabric

edge notes because they happen to be at the edges of the software defined access fabric with at tunnel

LaBolt weeks lan connecting the two both concepts.

I mean the underlay and overlaid together create an S the a software defined access fabric.