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- Let's go over

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What is VXLAN and what
are network overlays.

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Now, many organizations use this concept

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of an overlay network model,

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basically deploying an overlay network

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allows you to tunnel layer through packets

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with different Encapsulations.

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Right.

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And basically,

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you're doing this layer two tunneling

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over a layer three network.

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So this overlay network
uses quote unquote tunnels

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to carry traffic across
the layer three fabric.

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And these solutions needs
to allow the underlay

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to a separate network flows
between different tenants

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or administrative domains.

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Now, the solution also
needs to switch packets

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within the same layer two broadcast domain

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and also route traffic between

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layer three broadcast domains
and provide IP separations.

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And traditionally, this is actually done

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via things like virtual
routing and forwarding

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or VRFs

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But nowadays, a lot of
organizations actually

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are using VXLAN to provide
this type of functionality.

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Now, there have been many
multiple tunnel mechanisms

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as I mentioned now, these are some

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of the most popular,
you know, historically

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we

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I just mentioned VXLAN which stands

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for Virtual Extensible LAN.

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And you also have the
Network Visualization

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with Generic Routing
Encapsulation, or NVGRE.

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You also have the Stateless
Transport Tunneling protocol

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or STT.

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And the Generic Network
Visualization Encapsulation

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or G E N E V.

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Right?

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So GENEV.

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Now the use of UDP in VXLANS
basically enable routers

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and network infrastructure
devices to apply

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hashing algorithms on
the outer UDP header to

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basically low balance the network traffic.

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The network traffic
that is actually writing

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the, you know the overline network.

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It's actually load balance

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over multiple links using
equal-cost load balancing

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or equal cost multi-path routing ECMP.

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Now this introduces a
little bit better solution

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compared to the traditional
network designs.

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In traditional network designs,

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access switches connect to
the distribution switches

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and this actually cause redundant links

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to block due to spanning tree.

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And this case a VXLAN uses an identifier

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or a tag that represents a logical segment

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that is called a VXLAN network identifier,

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or a VNID.

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Now the logical segment
is identified with a VNID

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and it's basically a
layer two broadcast domain

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that is tunneled over the VTEP tunnels.

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Or the VTEP tunnel.

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Now here, I'm actually showing an example

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of an overlay network
that provides a layer two

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you know, tunneling capabilities.

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And in this other example,

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I'm showing an overlay network

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that provides layer three
routing capabilities.