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[AUDIO LOGO]

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So now that we've talked about
how route dampening actually

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works and what
it's for, now it's

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time to jump into
the command line

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and actually see it in action.

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So let's, of course, bring
up our topology first

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so we know what we're going
to be implementing and where,

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and then we'll jump
into that command line

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and see all of this in action.

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So, for this demonstration, we
will be using BGP Topology 1,

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and we're going to configure
our route dampening

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on router 1, that way,
we can see it on IOS XR

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and we'll also configure
it on router 7.

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And then we're going
to have router 6 create

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our problems by withdrawing
and advertising routes

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numerous times.

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So that's our game plan.

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Let's start by jumping in and
starting to configure router 1.

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So we'll begin here on router 1.

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And let's start by
making a prefix-set.

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We don't necessarily
need this, but if we

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want to control the route
dampening separately for, say,

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prefixes or for
different neighbors,

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then we're going to
want to write a route

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policy to do this.

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Although keep in mind, we can
apply this as just a blanket

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policy.

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And we'll see how
to do that as we go.

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But we'll still start off
here with a prefix-set.

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We'll just call it eBGP_PEERS.

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And for now, that's just
going to be 50.0.167.6.

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We'll just put router 6 in
there and we'll end the set.

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Then we'll write
our route policy.

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We'll call this RP_RFD.

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And we'll say, if the source--

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this way, we're going to be
matching on the route source--

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is in our PS_eBGP_PEERS, then
what we're going to want to do

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is set the dampening.

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Now just to start taking a look
at how this gets built out,

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here we can either put in the
halflife, the max-suppress,

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the reuse, or the suppress.

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So we have to start
putting in the numbers.

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So let's start
off with halflife.

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And just to not use
the defaults here,

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let's set this to, say, 10.

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And by the way, notice
the others here.

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We could just tell it to use
the other default values.

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So realistically,
we really only have

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to specify one of these
numbers, but the rest of them,

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we could set to the default.

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Now, we're not going to do that,
so let's back up over that.

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And let's instead say--

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let's do a reuse limit
of, let's say 500.

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Let's do a suppress of 2,500.

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And again, this is really
just not to use the defaults.

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And we'll set the max-suppress
time to 30 minutes.

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Then we'll just pass
the rest of the prefixes

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if they're coming from
a different neighbor.

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And we'll exit
out of our policy.

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Next up, of course, we
have to go into router BGP.

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So router BGP 100 for the
address family iPv4 unicast,

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and we say BGP dampening.

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Now, note here if we get
contact-sensitive help,

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we can, of course, call
to our route policy,

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which is why we just wrote it.

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But notice we could
also just start

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configuring the halflife time
and everything right here.

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If we do it right here, that
would be for everything--

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all prefixes learned
from all neighbors--

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but if we want to
be specific, again,

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either per neighbor
or per prefix--

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because of course, we
could have really matched

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on anything in our route policy.

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We matched on a route
source being a neighbor,

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but it could have been
on prefixes or whatever

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we wanted to match on.

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If you want to do
it for everything,

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you can just set it right
here on this command line.

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We didn't need
the prefix set, we

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didn't need the route policy.

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But this is, of course, a little
bit more interesting to do it

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with the route policy, so let's
just go ahead and continue.

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So here, all we have to do is
actually apply that policy,

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then we'll commit our changes
and exit configuration.

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So now let's go do the exact
same thing on router 7.

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Of course, the configuration
is a little bit

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different on IOS XE.

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First, we use a prefix-list.

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We'll pretty much call
it the same thing.

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We'll use PL instead of PS
since it's a prefix-list instead

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of a prefix-set.

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But beyond that, it'll
be pretty much the same.

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Once again, is going to be
matching on the 50.0.167.6.

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And we'll match on
that as a host route

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since it's the actual
address of our neighbor.

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So we'll just match
on it as a slash 32.

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Of course, it's not a
route policy on IOS XE,

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it's a route map.

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We'll call this RM_RFD.

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And we'll start with stanza 10.

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What we're going to
do is we're going

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to match on the IP address
based on the prefix-list,

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PL_eBGP_PEERS, and we're
going to set the dampening.

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This is done a little
bit differently.

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We don't actually put the
words in here, which means

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they go in a specific order.

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So the first thing
is the halflife time.

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We'll use the same numbers,
so we'll set this to 10.

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The next thing is going to be
the penalty to start reusing

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a route-- so, in other
words, the reuse limit--

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we had set this to 500.

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Then it wants to
know when it should

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start suppressing the route.

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So that we set to 2,500, and
then we have the max duration,

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and this is going to be 30.

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That's all at once,
so we'll hit Enter.

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Then we'll go into
our router BGP 65001.

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And under BGP dampening,
notice once again, we

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could just put the
entries here or we

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can call to our route map.

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So just like on IOS XR,
this would be global

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if we just start
putting numbers here

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or we call to our route
map to do specifics.

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So now that we're
all configured, now

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we need a route
to actually flap.

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So let's go over to router 6.

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And the first thing we're going
to do is create a new loopback

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and advertise it into BGP.

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And again, this is something
we've done numerous times,

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so we don't really
need to see it.

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I'll just paste the
configuration in.

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So we've created a Loopback100.

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We can see the loopback
interface is coming up.

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And if we give it
just a second here,

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it should show up in BGP as
well if we do a show ip bgp.

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Here, we have the 100.6.6.6/32.

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The next Hop is all
zeros, indicating

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we're locally injecting it.

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And the default
wait there of 32768

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also indicates it's
locally injected.

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So now that it's
been advertised,

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let's actually make this flat.

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So let's go back
into configuration,

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back into interface,
loopback100, and let's

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shut it down.

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We'll just start with that.

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And now let's go look at
what's happening on router 7.

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So on 7, let's do a show bgp
ipv4, unicast, dampening,

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flap-statistics
for the 100.6.6.6.

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Let's look at router 1 as well.

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Let's start with a show BGP.

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What this will actually show us
is that dampening is enabled.

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We can see it right here.

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So now let's see if it's
actually counted that.

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So now let's do a show bgp
ipv4 unicast flap-statistics

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100.6.6.6.

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Notice it's showing it
as a historical entry.

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So now let's flap
router 6 a few times.

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So now let's do a no shut.

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We'll let it come back
up, we'll shut it again.

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And let's go look at
the routers again.

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Here on router 7,
we might notice

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that we're having a problem.

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Notice that I've actually
repeated this a few times.

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And we're not getting
any flap-statistics,

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which really looks like
router 7 is not working.

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Because if we go over to router
1, if we look at this again,

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notice that this has it
as a historical entry,

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it's showing a
couple of Flaps here.

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So obviously, the
route is flapping,

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but router 7 is not showing it.

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So if we go back over
here to router 7,

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we can see right here the line
where we applied our dampening.

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So we did bgp dampening
route-map RM_RFD--

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that seems correct.

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So let's do a show
route-map RM_RFD.

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And actually, what
we can see here

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is that we made a mistake
when putting the route map in.

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We actually matched
on the IP address

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based on the prefix-lists,
but it should

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have been on the route source.

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So we're going to
have to correct this.

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So actually, let's just
say no route-map RM_RFD.

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It's not a very
complicated route map.

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We'll just put it in again.

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So we'll recreate our route map.

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It's, of course, yelling at
us here because I deleted

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the route map that it's
using for dampening,

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but it'll correct
it in a minute.

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This should not have
been match ip address.

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This should have been
match ip route-source

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and then set the dampening.

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We'll look at the
route-map again,

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and we can see that now it's
matching on the route-source

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based on the prefix-list.

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So now let's see if it's showing
our dampening statistics.

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Let's cause one more
flap or maybe a couple.

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And we'll see if 7
is counting it now.

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I'm just going to take this
off and put it back on.

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It probably really
confused it when

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we took the route map out that
it was using for its dampening,

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so we'll reapply it because it's
still not counting it properly.

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OK, so there's nothing
shown right now.

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And I know that got messed up
with the console message there.

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Let me do it again.

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There's nothing being
shown on this output,

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but see that we're at least
getting output, which means

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that now it's properly enabled.

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So now we can properly
do our testing.

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So now let's go back and
flap it a few more times

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and see where we're at.

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So we'll bring it back
up, shut it back down,

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and let's go see where we are.

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We can see here on router 7
that it is now properly tracking

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the dampening, and we can
see that it's flapped twice.

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So now we'll go ahead and
flap this enough times that it

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actually goes to suppressed.

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All fast forward until
it does that because we

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do have to wait 30 seconds
between each flap for this

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to work properly,
so this is going

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to take just a
couple of minutes.

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So now that we've flapped
this just a few times,

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we can see here it's
listing it as four flaps.

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We can see that this
is now being dampened.

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And we can see that
it's going to be reused

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in 4 minutes and 49 seconds.

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If we say show ip
bgp for the prefix,

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we can also see the
dampening information here.

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We see that its current
penalty is 3,024,

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it's flapped 4 times in the
last 7 minutes and 39 seconds,

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and again, it's going
to be reused now

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in 4 minutes and 9 seconds.

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So we can see that not only
does it keep track of the fact

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that it's dampened-- we
also see, by the way,

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it says suppressed due to
dampening-- but it also

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lets us know automatically
it's calculated

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the halflife timer,
the current penalty,

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and it knows when it's going
to get back to the reuse limit,

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and it's already calculated
that time for us.

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We can verify this over
on router 1 as well.

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So first, we can just
look at the statistics.

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This, of course, shows
us that it's dampened,

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00:12:21,820 --> 00:12:24,280
and it also gives us that reuse.

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00:12:24,280 --> 00:12:28,900
Now, remember that router 1
was working, to begin with.

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And router 7 had a
little bit of an issue

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00:12:31,930 --> 00:12:34,600
because we put in our
route map incorrectly.

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00:12:34,600 --> 00:12:38,410
So notice that router 1 has
seen quite a few more flaps.

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Its reuse is 27 minutes.

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00:12:42,020 --> 00:12:45,010
So it sees the penalty
as being a lot higher.

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00:12:45,010 --> 00:12:48,260
We can also say
detail on this output,

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00:12:48,260 --> 00:12:51,550
and we can see all
those statistics that we

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00:12:51,550 --> 00:12:53,200
entered for the configuration.

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00:12:53,200 --> 00:12:55,780
We see the halflife
timer of 10 that we

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00:12:55,780 --> 00:12:59,470
put in, our suppressed
limit, our reuse limit,

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00:12:59,470 --> 00:13:02,440
and we see that
max suppress time.

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00:13:02,440 --> 00:13:05,530
If we do a show bgp
for that prefix,

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we see that once again, it says
suppressed due to dampening,

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00:13:08,830 --> 00:13:11,170
and we see the
dampening information.

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00:13:11,170 --> 00:13:14,740
It currently has a
penalty of 3,118.

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00:13:14,740 --> 00:13:18,370
It's flapped 7
times in 18 minutes,

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00:13:18,370 --> 00:13:24,490
with a reuse in 26 minutes
and 20 seconds now.

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00:13:24,490 --> 00:13:27,760
So this is how BGP
route dampening works.

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00:13:27,760 --> 00:13:32,260
If you know that this has become
stable, maybe the customer

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00:13:32,260 --> 00:13:34,760
called us up and told
us, hey, we had an issue,

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00:13:34,760 --> 00:13:36,760
but it's all been
fixed now, can we

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00:13:36,760 --> 00:13:39,530
get this to not be
dampened anymore?

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00:13:39,530 --> 00:13:41,270
We can do that as well.

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00:13:41,270 --> 00:13:42,850
Now, these are
some long commands,

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00:13:42,850 --> 00:13:44,920
so I'm just going to
copy and paste them in,

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00:13:44,920 --> 00:13:48,970
but we can clear both the
statistics and the fact

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00:13:48,970 --> 00:13:50,860
that it's currently
being dampened,

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00:13:50,860 --> 00:13:55,790
and get this route to come back
earlier if we choose to do so.

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00:13:55,790 --> 00:13:57,940
So here on router
1, we'll simply

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00:13:57,940 --> 00:14:00,740
clear these two
pieces of information.

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00:14:00,740 --> 00:14:05,020
So the first one is to clear bgp
ipv4 unicast dampening and then

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00:14:05,020 --> 00:14:06,220
for the prefix.

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00:14:06,220 --> 00:14:09,080
And again, the second command
got buried there a little bit,

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00:14:09,080 --> 00:14:11,840
so let me just hit the up
arrow so you can see it.

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00:14:11,840 --> 00:14:16,420
It's the clear bgp ipv4
unicast flap-statistics

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00:14:16,420 --> 00:14:18,850
for that prefix.

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00:14:18,850 --> 00:14:22,260
So now if we do a show
bgp for the 100.6.6.6,

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00:14:22,260 --> 00:14:24,780
we can see that now
it's being advertised

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00:14:24,780 --> 00:14:29,380
and it doesn't have any of the
flap statistics counted for it.

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00:14:29,380 --> 00:14:32,580
So basically, we manually
just wiped the slate clean

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00:14:32,580 --> 00:14:35,010
and got this to
be re-advertised.

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00:14:35,010 --> 00:14:38,250
We can do the same
thing on IOS XE.

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00:14:38,250 --> 00:14:41,130
And believe it or not, I can
just paste these commands in.

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00:14:41,130 --> 00:14:45,360
They're the exact same
commands on both platforms.

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00:14:45,360 --> 00:14:49,420
We'll do our show ip bgp
for the prefix again.

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00:14:49,420 --> 00:14:52,410
And as we see here,
just like on IOS XR,

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00:14:52,410 --> 00:14:54,840
all of the flap
statistics are gone,

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00:14:54,840 --> 00:14:58,210
and the prefix is
being advertised.

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00:14:58,210 --> 00:15:01,710
So again, we just manually
wiped the slate clean.

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00:15:01,710 --> 00:15:03,720
Clearly, we would
only do this if we

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00:15:03,720 --> 00:15:07,180
had reason to suspect that
yes, there had been a problem,

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00:15:07,180 --> 00:15:09,015
but yes, now we know
it's cleared up.

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00:15:09,015 --> 00:15:11,550
s So like in the
example of router 1,

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00:15:11,550 --> 00:15:14,250
let's not make the
customer wait 30 minutes.

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00:15:14,250 --> 00:15:16,950
We can go ahead and
clear those statistics

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00:15:16,950 --> 00:15:20,620
and dampening right now.

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00:15:20,620 --> 00:15:25,410
So in this video, we saw how to
configure BGP route dampening

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00:15:25,410 --> 00:15:29,650
on both IOS XR and IOS XE.

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00:15:29,650 --> 00:15:33,420
Remember you can set
these numbers directly

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00:15:33,420 --> 00:15:35,860
under the routing
process itself,

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00:15:35,860 --> 00:15:38,190
and that's just going
to be global then.

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00:15:38,190 --> 00:15:41,310
That's going to be for all
neighbors, all prefixes,

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00:15:41,310 --> 00:15:45,150
or you can go the way
we went, which is using

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00:15:45,150 --> 00:15:48,240
a route map or a route policy.

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00:15:48,240 --> 00:15:50,940
Just make sure you write
your route maps correctly,

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00:15:50,940 --> 00:15:52,530
unlike what we did.

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00:15:52,530 --> 00:15:55,080
The problem, of course,
what we did here

315
00:15:55,080 --> 00:15:58,110
is we did our prefix list
based on the route source,

316
00:15:58,110 --> 00:16:00,990
but then told it to match on the
address rather than the route

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00:16:00,990 --> 00:16:01,560
source.

318
00:16:01,560 --> 00:16:04,620
We could have matched
on either one.

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00:16:04,620 --> 00:16:07,800
We just would have had to
write our prefix list a little

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00:16:07,800 --> 00:16:13,650
differently so that it was
matching on the 100.6.6.6/32

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00:16:13,650 --> 00:16:16,470
rather than the actual
address of the neighbor,

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00:16:16,470 --> 00:16:18,100
but either way is fine.

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00:16:18,100 --> 00:16:22,830
We can match on either prefixes
or neighbors in our route

324
00:16:22,830 --> 00:16:28,080
policies and prefix sets and
route maps and prefix lists.

325
00:16:28,080 --> 00:16:30,440
We can match on
whatever we want to.

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00:16:30,440 --> 00:16:33,850
We just have to be consistent
with what we're doing.

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00:16:33,850 --> 00:16:35,880
I hope this has been
informative for you,

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00:16:35,880 --> 00:16:38,900
and I'd like to thank
you for viewing.

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00:16:38,900 --> 00:16:42,000