- Let's go over
What is VXLAN and what are network overlays.
Now, many organizations use this concept
of an overlay network model,
basically deploying an overlay network
allows you to tunnel layer through packets
with different Encapsulations.
Right.
And basically,
you're doing this layer two tunneling
over a layer three network.
So this overlay network uses quote unquote tunnels
to carry traffic across the layer three fabric.
And these solutions needs to allow the underlay
to a separate network flows between different tenants
or administrative domains.
Now, the solution also needs to switch packets
within the same layer two broadcast domain
and also route traffic between
layer three broadcast domains and provide IP separations.
And traditionally, this is actually done
via things like virtual routing and forwarding
or VRFs
But nowadays, a lot of organizations actually
are using VXLAN to provide this type of functionality.
Now, there have been many multiple tunnel mechanisms
as I mentioned now, these are some
of the most popular, you know, historically
we
I just mentioned VXLAN which stands
for Virtual Extensible LAN.
And you also have the Network Visualization
with Generic Routing Encapsulation, or NVGRE.
You also have the Stateless Transport Tunneling protocol
or STT.
And the Generic Network Visualization Encapsulation
or G E N E V.
Right?
So GENEV.
Now the use of UDP in VXLANS basically enable routers
and network infrastructure devices to apply
hashing algorithms on the outer UDP header to
basically low balance the network traffic.
The network traffic that is actually writing
the, you know the overline network.
It's actually load balance
over multiple links using equal-cost load balancing
or equal cost multi-path routing ECMP.
Now this introduces a little bit better solution
compared to the traditional network designs.
In traditional network designs,
access switches connect to the distribution switches
and this actually cause redundant links
to block due to spanning tree.
And this case a VXLAN uses an identifier
or a tag that represents a logical segment
that is called a VXLAN network identifier,
or a VNID.
Now the logical segment is identified with a VNID
and it's basically a layer two broadcast domain
that is tunneled over the VTEP tunnels.
Or the VTEP tunnel.
Now here, I'm actually showing an example
of an overlay network that provides a layer two
you know, tunneling capabilities.
And in this other example,
I'm showing an overlay network
that provides layer three routing capabilities.