Technology does evolve.
And with DMVPN, that's no exception.
We have three major phases of DMVPN.
And that's what I'd like to chat with you about in this video.
And here's the key differences with the three phases.
With phase of DMVPN, all traffic with DMVPN
had to go through the hub.
Now, it was still better than doing
site-to-site traditional VPN tunnels,
because we didn't have to manually configure
all the details for all the tunnels. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
all the details for all the tunnels.
We could set up the spokes.
They registered.
And there was no spoke-to-spoke tunnels that were created.
So all traffic would go up, and then down.
Reply traffic would go up, and down.
And there was never any spoke-to-spoke traffic.
DMVPN phase two introduced the spoke-to-spoke or
branch-to-branch traffic for DMVPN.
And the way they did that was R4 would look at its routing table
and say, oh, to get to 172.16.2.
something based on that route, it's
going to be the next hop of 10.0.0.2. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
going to be the next hop of 10.0.0.2.
And it wouldn't know the address of that.
So it'd make a request and get the response,
and then build a tunnel.
And that is DMVPN phase two with specific ability
for spoke-to-spoke tunnels.
And the third option or the third phase for DMVPN
is for explicit routes to be added into the routing table.
And here's how phase 3 fits into the picture.
With phase 3, we can still have our starting point
for the tunnels.
We can still build the individual tunnels
between the spokes, but we also have the option WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
between the spokes, but we also have the option
of more detailed routes.
Let me show you what I mean.
Let's say R1 on its tunnel interface
created a summary for EIGRP, and said,
I'm creating a summary of 172.16.0.0 with a 16-bit mask.
Now, if it created that summary on the tunnel interface,
that means these detailed routes wouldn't be
advertised to the other spokes.
All they would see is their own local network,
because it's local.
And they would see the summary.
And they wouldn't see the more detailed routes, because that's
what a summary does.
It hides the more detailed routes. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
It hides the more detailed routes.
So in the event R2 needs to send a packet to 172.16.4, what it's
going to do, it's going to go ahead and forward
the packet up to R1.
But instead of just routing the packet through the hub,
there is some redirect messages that happen.
So at the end of DMVPN phase 3, there's
redirects to instruct the network, hey,
I'm not the best--
I'm not really the best next hop for that.
It can educate R2 on what is the next hop.
They can still build the tunnel between R2 and R4.
And along with that, R4 can advertise the details WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And along with that, R4 can advertise the details
for that 172.16.4 network.
And that can be added or included
in the routing table of R2 for future use.
So R2 would have the local network here, 172.16.2.
It would know about the summary still.
And it would also have a specific route of 172.16.4
that it would know that R4 is the next hop 4.
So the phase 3 allows for redirects, and also routes
being dynamically added to the routing table of a router
so that for future packets it can go directly to the next hop WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
so that for future packets it can go directly to the next hop
without having to go through the hub.
And the syntax to add phase 3 for DMVPN is on the hub.
We'd use the command ip nhrp redirect.
So it can redirect the individual client
who's asking about getting better information.
And on these spokes, it's ip nhrp shortcut.
So the redirect on the hub does the redirect messages.
And then the clients with the ip nhrp shortcut on their tunnel
interfaces allows those spoke routers, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
interfaces allows those spoke routers,
when they learn that information about a more detailed network,
to go ahead and add that dynamically
to its routing table.
In this set of videos, we've taken a look
at the world of DMVPN, including some hands-on labs
so you can practice implementing and verifying it,
both with and without IPSec.
I've had a blast.
I'm glad you joined me for these videos.
And I'll see you in the next set of videos.
Meanwhile, I hope this has been informative for you.
And I'd like to thank you for viewing.