[AUDIO LOGO]
Our first step in configuring PIM sparse mode
will be to enable multicast routing
on the devices themselves.
Multicast routing is not enabled on our routers by default.
Just because a lot of companies choose
not to use multicast routing, Cisco
has elected not to enable that feature automatically.
The next thing we have to do is enable PIM in sparse mode
on the appropriate interfaces.
So the first thing we should probably do here
is bring up our topology diagram,
get a look at what we're going to be building overall,
and therefore which routers need multicast routing enabled
and on which interfaces.
So let's go ahead and start with our topology diagram.
Then of course, we're going to jump into the command line
and get PIM sparse mode up and running
on our routers and interfaces.
So for this skill, we are going to be on multicast topology 1.
And in this topology, what we're going to be doing
is we're going to use router 10 up here
is the source for our multicast traffic.
And we're going to use router 8 down here
as the receiver or the client.
So these two routers themselves will not
be running multicast routing.
That means where we do need multicast routing is
going to be on everything else.
Router 9 here is a little bit optional.
We don't necessarily have to run multicast routing on router 9.
We could do it for a redundant path
in case this link were to file or something along those lines.
But we don't really need it on router 9 either.
We're going to be focusing on routers 1
through 7 for our multicast environment.
Now, that means that we're going to want
to turn on multicast routing on all
of the interfaces on these devices.
So that would take care of all of the interfaces facing
other routers.
But don't forget that on the first hop router,
we also need PIM on the interface facing the source.
So we would need this on gigabit 2 on router 6 as well.
And we need the same thing on the receiver side.
So on gigabit 3 on router 7, our last hop router,
we will need PIM enabled there as well.
Because again, a Cisco router will not
forward the traffic if PIM is not enabled on that interface.
So these are the interfaces and routers
that we're going to need to enable PIM on.
Let's go ahead and jump over to the command line
and get that working.
So we'll begin here on router 1.
And on IOS XR, we'll do this by going into multicast routing.
Under the multicast routing configuration mode,
the next thing we're going to want to do here
is go into the appropriate address family.
So we'll simply say address family ipv4.
And then we need to start enabling our interfaces.
So here we'll say interface.
And we'll start with gig 0/0/0/0.
And all we have to do for right now
is simply enable each interface.
So next we'll do gigabit 1.
This router also needs gigabit 2 and gigabit 3.
Now, this does include the interface up
to router 9 just in case we decide
to do that at some point.
We'll commit these changes, exit configuration.
And now if we do a show PIM interface,
we'll see that PIM is now enabled
on all of those interfaces.
The default version of PIM here on IOS XR is PIM version 2.
And we currently see that we don't actually
have any neighbors.
Now, it is a little bit interesting
to note here that it lists the neighbors as 1
because it counts itself.
But once we get neighbors actually up and working,
we'll see that this will actually
change to 2 when it's a point-to-point connection
between two routers.
So keep in mind that that neighbor count of 1
is simply the router referring to itself.
So now let's go do the same configuration on router 2.
Again, this will be almost identical.
However, this does have less interfaces.
So again, we simply go into multicast
routing configuration mode.
And just another quick note, there
is also a router PIM configuration mode
that we will use to configure things about PIM itself.
But just to enable multicast routing,
this is all we have to do.
And this does include actually enabling
PIM on those interfaces.
Now, we can do that in PIM configuration mode as well.
We can also go into interfaces and enable them.
However, we don't have to do that if we enable it here.
But again, there is still that router PIM configuration mode
that we'll use later for configuring specific things
about PIM itself.
Again, the next thing is to go into the address family
and then into the interfaces.
Now, on this router we need gigabit 0, 1, and 2.
Commit the changes.
Exit configuration.
Let's do our show PIM interface again.
So notice two things here.
The first is we do, in fact, have PIM
enabled on the three interfaces that we enabled it on,
our gigabit 0, 1, and 2.
But also note that on gigabit 0, which is the one facing router
1, the neighbor count is now 2.
That's because it actually has a neighborship with router 1.
If we do a show PIM neighbor, we can actually
see how on the gigabit 0 interface,
it's actually listing both neighbors, router 1, which
is the 12.1, and of course, this router, router 2,
which is the 12.2.
So we can see how it's listing itself as well as
the other legitimate neighbor.
Next we'll do router 3.
Now, we've seen IOS XR a few times now.
So we'll just go ahead and paste this configuration
in since we've already seen it.
This router needs interfaces 0, 1, and 3.
We can, of course, verify with the show PIM interface.
We see that this is now enabled.
And we can see here that it has a neighbor count of 2
on the gigabit 0/0/0/1 interface,
which would be the interface up to router 1.
So again, if we do a show PIM neighbor,
we can see that the neighborship on gigabit 0/0/0/1 is in fact
up between router 1 and router 3.
So finally let's do router 4.
Once again, we'll simply paste that configuration.
This is just two interfaces, gigabit 0/0/0/0 and 0/0/0/1.
Just for a final verification, let's just
go ahead and jump right to the show PIM neighbor this time.
Because if the neighbors are up, of course,
the interfaces are enabled.
And we see that on both our gigabit 0 and our gigabit 1
interface, we are listing two routers.
So the first one here on gigabit 0
is the neighborship between routers 3 and 4.
And the second one is between routers 2 and 4.
So this tells us, of course, that router 4 here is in fact
up with routers 2 and 3.
So, so far, everything looks good.
So now let's move on to router 5, which, of course,
is our first IOS XE router.
So this configuration is, of course,
going to be a little bit different.
So we'll, of course, start by going into configuration mode,
and then we have to enable multicast routing globally.
So we say ip multicast-routing.
And just a quick note here, depending on the IOS version,
you might just have to hit Enter right here.
Some versions of IOS XE, however, this version included,
we have to actually add the keyword distributed.
Let's take a look.
Notice that if we hit the question mark,
we can, of course, enable this for a particular VRF.
Or we can say distributed as I just mentioned.
But notice that hitting Enter here is not an option.
It simply tells us it's incomplete.
Even if I were to say vrf, give it, of course,
a name for a VRF, we'll say default,
it still wants the keyword distributed.
So on this particular platform, we
are going to have to say distributed and hit Enter.
So that enables multicast routing for the whole router.
If we were to do a show IP interface, what we'll see
is, of course, that by default, that doesn't
enable PIM on any interfaces.
That's simply enabling multicast routing globally.
So now we have to go into each individual interface.
On router 5, we're going to need interface gigabit 1.
And we enable this by typing ip pim.
And here we can see a lot of different choices.
But what we're looking for right now is to enable sparse mode.
So if we say sparse, notice it's going
to stop here because we could either say sparse mode
or sparse dense mode.
Sparse dense mode is sort of an older
way of supporting Auto RP.
We'll talk more about that a little bit later.
But for now we just want sparse mode.
So we'll say sparse-mode.
Also just a quick note on that as we see our neighbors coming
up here, if you just say sparse, it
will actually default to sparse mode
instead of sparse dense mode.
We'll do that on the other interfaces.
For example, if I said interface gigabit 2,
and then I were to say ip pim sparse
and not actually finish the command, it will take that.
It doesn't take it as an ambiguous command.
We can see the neighbors already coming up.
So that should give us a pretty good indicator
that it enabled it.
But in what mode?
Well, if we say do show run for interface gigabit 2,
we'll see that it actually put it in as IP PIM sparse mode.
So this is sort of a unique little command
that it defaults to sparse mode when there is technically
an ambiguous choice, which would be sparse-dense-mode.
So just an interesting thing to note.
It does, of course, make it easier for us to type it in.
And we rarely need sparse dense mode.
So this is usually fine.
Just keep in mind that if you do need sparse dense mode,
you're going to have to type the whole thing in.
Because otherwise, it will default here
to just sparse mode if all you type is sparse.
So we can exit configuration.
Let's do a show IP PIM interface.
So we see now that our two interfaces
are, in fact, running PIM.
We see that they are in version 2.
The S indicates that they are in sparse mode.
We see that we have two neighbors
on each of these interfaces.
And what's interesting about this
is if we say show IP PIM neighbors, what we'll see
is here on IOS XE, it's only actually listing the neighbors.
It doesn't list ourselves on this output.
Just a minor difference between IOS XR and IOS XE.
So we see here that router 5 is up
with routers 1 and 3 on the gigabit 1
interface as it should be.
And on interface 2, it is up with neighbors 4 and 2.
So this appears to be working correctly.
Let's go ahead and do router 6.
Once again, router 6 is almost an identical configuration.
So we'll just go ahead and paste the configuration in.
This is going to get enabled on two interfaces,
gigabit 1 and gigabit 2.
We can see here that the neighborship with router 1
has already come up as it should.
We can, of course, verify that with a show IP PIM neighbor.
We see that this neighborship is up.
It's been up for 23 seconds.
And it is PIM version 2.
Let's go ahead and configure router 7 as well.
Once again, almost identical configuration,
just two different interfaces as gigabit 2
and gigabit 3 on router 7.
Once again, we see our neighborship
with router 3 this time coming up.
And if we do the show IP PIM neighbor,
we'll see that neighborship is up.
And, again, it's version 2.
So that brings all of our neighborships
up as we need them.
So in this video, we saw how to enable PIM sparse mode
on both IOS XR and IOS XE.
We saw that we had to enable it globally and then also enable
it on each interface.
Now, that, of course, is done a little bit differently
between XR and XE.
But the same basic process had to happen on both platforms.
Now, none of this does us any good,
particularly with sparse mode, until we have a rendezvous
point.
So we need to configure a rendezvous point.
And that's exactly what we're going to do next.
Until then, I hope this has been informative for you.
And I'd like to thank you for viewing.