So what are the building blocks and the ingredients
that go in to make this wonderful DMVPN possible?
That's the topic of this video.
And I'm going to give us a big head start here and a leg up
in the world with understanding DMVPNs
by sharing with you some of the terms,
and also the networks that are currently in use in this lab.
So that way, when you see an address,
you'll think, OK, I know what that is.
Because sometimes when topologies are used,
or example configs are used, and they're using RFC 1918 WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
or example configs are used, and they're using RFC 1918
addresses on both sides.
You think, well, which ones the GRE network?
And which one's the publicly reachable addresses?
It'll help in this topology, which
matches our lab, by the way, to have a clear picture of which
addresses are used where.
And that way, when you see them, you'll know what they are.
So let's start off with internal networks.
In this lab topology, I've got-- well,
there's four routers we're going to be playing with.
There's actually another router sitting right here
in the middle acting as a pseudo internet.
But it doesn't need to be configured
as part of our DMVPN solution. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
as part of our DMVPN solution.
It's just representing the internet of publicly routable
address spaces.
So as far as internal networks go, I put them in red.
So up here at site 1, we've got 172.16.1.
It's a 24-bit network.
Down here at site 2 in red, I've got the 172.16.2 network.
Down here at site 3 with R3, 172.16.3.
And down here at R4, it's address space is 172.16.4.
And all the routers consistently have
the last octet of their IP address
match their router number.
So when you see .1, you'll think, oh, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So when you see .1, you'll think, oh,
that's .1, router 1, and so forth.
So that's the internal networks.
Check.
And then what's with the sideways check?
Check.
All right.
Good enough.
Next, public IPs.
I put the public IPs in this kind of--
whatever color that is.
The color that matches here.
And this network here that R1 is connected to--
and again, for the purposes of education,
I'm using addresses that are routable on the internet,
not RFC 1918 addresses. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
not RFC 1918 addresses.
But also very carved out, so that when you see network 11,
you'll know, oh, that's the network that's directly
connecting R1 to the internet, or to our pseudo internet.
Or network 22, that's the network
that R2 is using to directly connect to the internet.
And network 33, R3 is using that one.
And 44, and so forth.
So those are the publicly routable addresses
on our little pseudo internet.
And again, each router ends with its router number.
I also want to point out this term right here, NBMA.
Well, a Non-Broadcast Multi-Access, NBMA. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Well, a Non-Broadcast Multi-Access, NBMA.
In the documentation or in the CLI,
when you're working with DMVPNs, and you
do context-sensitive help.
And it says put the NBMA address,
it's referring to the publicly routable address.
Think of it as a valid routable address.
In this case, the internet routable
addresses that we're using the 11 network, and the 22 network,
and the 33, and 44, and so forth.
So if it says NBMA, it's referring
to the routable public addresses.
And then for the VPN or GRE addresses, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And then for the VPN or GRE addresses,
which we haven't put in here yet,
those will be the networks-- let me see
if I can get a similar color.
This might be-- yeah, that's similar.
That's close.
When we build these GRE dynamically generated tunnels,
we're going to use tunnel 0 for each of them.
And GRE is protocol 47.
And then the IPsec profile on top of that tunnel interface
will cause all the traffic that's
GRE no matter where it's going to be encrypted.
And that also will trigger IPsec security associations
for IPSec between everybody who has a tunnel built. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
for IPSec between everybody who has a tunnel built.
But staying on topic here, for the tunnel networks,
for the GRE networks, it is going to look like this.
R1, I'll put R1 there.
In fact, let me just overlay it, because that's
how it will be anyway.
So from R1 to R2, there will be a V--
there will be a GRE network dynamically built
from their tunnel 0 interfaces.
From R1 to R3, and from R1 to R4.
And we might say, well, why does R1
get to be the person that every dynamically builds a tunnel to? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
get to be the person that every dynamically builds a tunnel to?
And that's because in the configuration
we're about to look at, he is the hub.
He or she is the hub.
So that's the start.
You have to have somewhere to start.
And so what we're going to do is identify one device--
usually, it's at the headquarter or main location--
that has a static address that we can point to,
or we can resolve it via DNS.
And then all the other devices, when they power up, they're
going to register with that guy, connect to him.
And that's why we can have dynamically assigned addresses
at the spokes.
If you have a spoke, like in Des Moines, or some other location, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
If you have a spoke, like in Des Moines, or some other location,
and it doesn't have a hard-coded static IP address
that it's using when it connects to the internet, no worries,
because this guy can build a tunnel dynamically.
And I'll report in on what his address is.
And R1 will then know, he has three clients.
They've all connected.
There's VPN tunnels there.
We are good to go.
So that's the starting point is that we
have to define one device as a hub
to point all the other spokes to get the ball rolling. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
to point all the other spokes to get the ball rolling.
And so this network that is in this color, the GRE networks,
we're going to use 10.0.0.
0 is the 24-bit mask.
And so when we configure the tunnel interfaces, on R1,
we'll just use interface tunnel 0.
And on R2, we'll use interface tunnel 0.
And R3 tunnel 0.
It doesn't have to match everywhere else,
but we don't need to create five tunnels or six tunnel
interfaces, just one tunnel interface.
And it's going to be a multipoint tunnel interface,
where that one tunnel interface can be used, and logically WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
where that one tunnel interface can be used, and logically
build the tunnels out to the other networks.
So in this network right here, it'll be the--
even though it's a grouping of point-to-point GRE tunnels
that are there, we only need one interface to actually peer
with everybody else.
The same thing with R2.
When R2 starts building tunnels to other spokes based
on traffic that needs to go, it doesn't
need to have a whole bunch of new tunnel interfaces.
It can spawn them off of the one multipoint GRE tunnel
interface.
And again, we're going to use the 10 network. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And again, we're going to use the 10 network.
An R1 will have on the tunnel, 10.0.0.1.
R2 will have 10.0.0.2.
R3 will have 10.0.0.3.
And R4 will have 10.0.0.4.
So knowing that ahead of time is going
to make the configuration go a lot easier when you come up
against IP addresses, and think, oh, what's that?
Or where is that?
Here it's clear.
So the 172.216's are all the inside networks
that are branches in a headquarter location.
The addresses of 11, 22, 33, and 44
represent publicly routable addresses.
And anywhere you see 10 anything, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And anywhere you see 10 anything,
that is absolutely the GRE tunnel interfaces on the tunnel
0 we're going to use in our configuration.
So that is the lay of the land regarding
this topology and the lab that we're
going to be dealing with and working with.
And what I'd like to do in the next video
is I want to keep these fairly short, nice and concise.
In the next video, let me walk you through the commands
that we could use on top of this topology, which include
the configuration for the hub, and what it looks like,
and why those commands are there.
We'll explain what they are.
And also the configuration that's WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And also the configuration that's
going to be virtually identical on all
of these spokes that are going to register and connect
into the hub.
So we'll cover all that in the very next video,
coming right up.
So I'll see you there in just a moment.
Meanwhile, I hope this has been informative for you.
And I'd like to thank you for viewing.