In this video, I'm going to share with you how
we can set up BFD to be used in combination
with a static route.
So if the next hop is not reachable for whatever reason,
we can go ahead and withdraw that static route
from our local routing table.
All right, so here's our game plan
for this static route with BFD.
Where going to use the same topology and as a reminder,
this is zero slash-- wow, look at that.
That's big.
[LAUGHS], erase that.
This is going to be zero slash two, this is zero slash zero, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
This is going to be zero slash two, this is zero slash zero,
and this is zero slash zero on this switch is connected too.
So what we're going to do as a demonstration,
let's create a static route on R2
that says that R4 is the next hop for the default route.
But if there is a problem with that next hop,
let's imagine that the switch we shut down the interface.
So we still have link.
But that next hop isn't available any longer.
Without doing some type of tracking or BFD operation here,
we're not going to know that that next hop isn't available WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
we're not going to know that that next hop isn't available
and we'll just keep that route in our routing table.
So let's do this.
We're going to go ahead and do the slow timers.
That line right there is really for the benefit of a lab,
so you're not going to blow up your gear because when
you have--
if you're an emulated environment.
We're going to go to gig zero two, this interface right here,
and we're going to specify the timers just as we've
done on each of the other implementations with BGP
and OSPF and EIGRP [INAUDIBLE] the interfaces,
what the timers are.
And then we're going to create-- use this command here.
It's IP route static BFD. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
It's IP route static BFD.
The interface, in this case is gig zero plus two,
and the neighbor, the next hop we're
going to use as part of that route, which is 10.24.0.4.
That's pointing to this interface IP address right
here on R4.
And then the command IP route and then
whatever route you want.
I'm putting a default route.
The exit interface, the egress interface,
and then the next hop itself.
Now the tricky part of this really isn't this part.
It's like, OK, I get it.
You're simply saying with BFD, use
that interface, that next hop.
But you have to have something running on the other side. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But you have to have something running on the other side.
On R4, if we don't have BFD also running and engaged,
it's not going to respond back and R2's
going to think it's always down.
So we're going to play a game on R4 called, I can do that too.
And it goes like this.
We're going to do the slow timer,
it's going to match it here.
We're going to specify the same intervals as we did here
except this time, we're doing on gig 0/0 on R4.
And then we're going to IP routing static BFD gig 0/0
because that's the interface.
Then we're going to specify R2's address. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Then we're going to specify R2's address.
But that's not enough, we also need to create a static route
to make it active.
So you're like me, you might be saying,
well, Keith, I don't need a static route on R4.
Well, if you want the BFD to work,
you're going to need to create a static route.
Now, we can point to something safe.
Like, we can say, an R4 IP route 10.24.0.2, which is basically
this IP address, which he is directly
connected on that network.
It's this last piece right here that allows the BFD to work.
So let's implement this.
Let's go to R2.
I'm going to go to R2 real quick. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I'm going to go to R2 real quick.
And here on R2 I will do a little cleanup.
Also, let me just verify I can ping the next hop.
10.24.0.4.
Great.
And let's do a trace, make sure I'm not going a weird way
through the network.
Yep, OK, great.
Straight shot there.
So R2 and R4 are adjacent.
We just show IP OSPF neighbors.
Right show IP EIGRP neighbors.
Fantastic, it's a party.
Show BFD neighbors. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Show BFD neighbors.
Neighbors, neighbors, neighbors.
Great, great, great.
And I still have all those protocols, OSPF, BGP, and EIGRP
all tied to BFD.
I didn't change that.
And we can verify that, once again, we show [INAUDIBLE]
BFD neighbor detail.
And from R2's perspective, we're looking for the neighborship
over to R4.
And there it is.
Scroll up a little bit, there's the neighbor.
10:24.0.4.
And we have each EIGRP CEF by default. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And we have each EIGRP CEF by default.
And BGP and OSPF all associated with it.
Great.
So let's add static to the mix.
So let's go back to our commands here,
and this is going to be on R2.
I'll copy this, through it on R2.
So now that we have that in place,
let me share with you what's going on
because in a production environment,
if you don't already have BFD set up on the other side,
it's not already active, it's just going to sit there.
So because I'm doing this on top of OSP--
OSPF is already set up with the BFD and EIGRP is and BGP. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
OSPF is already set up with the BFD and EIGRP is and BGP.
The BFG is already active over on R4, and as a result,
here on R2 do a show BFD neighbors detail.
And we go down to where it says 10.24.0.4, that neighbor, which
is this last one here.
You'll notice it now has EIGRP, BGP, OSPF and IPv4 static.
Now, that only happened because we had the previous BFD
configs actively involved on that interface in R4. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
configs actively involved on that interface in R4.
if you're doing it with just a static route without anything
else, what we would have to do is this part two
on R4, which is where you go in, make
sure you have the timer set up, and also set up the IP route
static and have an IP route.
And that turns on the BFD to create that session.
And the reason I point that out is
because if you just do this part by itself
and have no BFD anywhere else, R4 is not going to play ball.
So if you don't have it elsewhere,
you'd also need to do this part, which
is activating IPv4 static for BFD on that gig 0/0 interface WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
is activating IPv4 static for BFD on that gig 0/0 interface
over on R4.
So because it's already in place,
we don't need to duplicate that.
But check this out, let's do a show BFD neighbors.
So let's go ahead and test.
Let's just go up to the layer 2 switch,
and on the layer 2 switch we'll shut down the gig 0/0
interface.
BFD will fail, and what we should see that static route
that we have on R2 should drop out of the routing table
because it's tied to BFD.
All right, so here on switch two will go into interface gig 0/0.
Also on R2, just for a moment, let's do a show IP route. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Also on R2, just for a moment, let's do a show IP route.
Make sure that static route is there.
And we do a show IP route static, that'll work.
A little bit less output.
So there's our static route.
If we go to the layer 2 switch and do a shut down
on that interface, that goes over to R4.
The BFD is going to fail, go down,
and as result everything tied to it
is going to say, woah, that's a problem,
including the static route that we just made on R2.
So if we go back to R2, lots of messages here.
But we do the up arrow key, show IP route static, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But we do the up arrow key, show IP route static,
it's going to show us there is no longer a static route
present and that's because BFD that it was associated with
has gone down.
And as result, it's removing that route
from the routing table.
So thanks for joining me in this set of videos regarding
the concept of BFD, how it can improve convergence time
in a network, and I'll see you, my friend, in the very next
set of videos.
Meanwhile, I hope this has been informative for you
and I'd like to thank you for viewing.