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[AUDIO LOGO]

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So now that we have MPLS
traffic engineering enabled

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on our core, the next
step is, of course,

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going to be to configure
segment routing itself.

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We don't have that
configured yet so that's

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sort of going to be a necessary
component for segment routing

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traffic engineering.

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So let's go ahead and jump
in and get segment routing

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configured on our devices.

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We'll start off
with the topology

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because I want to show you
some stuff that we have already

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configured and what we're
going to be configuring.

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So let's bring up
the topology, then

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we'll jump into the
command line and we'll

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get segment routing up and
running in our network core.

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So again, we are still
on MPLS Topology 5.

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And what we really
want to talk about here

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is what's already
been configured.

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So what I've done is
I've already configured

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router 7, router 2, router
4, router 6, and router 8.

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So what we're going
to be working on

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is configuring the routers
across the top here, router 1.

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That way, we get to see an iOS
XR device running just IS-IS.

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Then we're going to
configure router 3

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so then we get to see iOS
XR with IS-IS and OSPF.

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Then we're going to
configure router 5.

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And of course, this
is running iOS XE.

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So that should
give us a good mix

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of being able to
see how to configure

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these different devices.

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So let's go ahead and
jump into the command line

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and get this configured.

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Let's just start on router 1.

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So let's start by enabling
segment routing for our IGP.

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In this case, it's
router IS-IS 1.

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Of course, we go into
the address family

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and we say segment routing MPLS.

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Commit the changes.

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So that takes care of router 1.

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Let's go do router 3.

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Now remember that router 3
is running two protocols.

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So let's start with
router IS-IS 1.

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Again, we just enable
segment routing for MPLS,

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then we'll go into
router OSPF 1.

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Also into our address
family, then into area 0.

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And then it's the same
command segment routing MPLS.

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Commit these changes.

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We can do some verification
as we go here as well.

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Let's do a show MPLS
label table detail.

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We see here that OSPF
and IS-IS are both

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registered with the SRGB.

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And we see down
here at the bottom,

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entries for both IS-IS
labels and OSPF labels

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for our adjacency sets.

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So so far, this is looking good.

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Let's go over to router 5.

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This being iOS XE,
we have to do segment

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routing MPLS globally first.

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Then we'll go into router
OSPF 1 and enable segment

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routing for MPLS here as well.

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Exit configuration.

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Here let's do a show
MPLS forwarding table.

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And we can see
that we're already

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learning adjacency sets.

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Notice that we also have
prefix SIDs for router 6

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and router 8
loopback, which are,

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of course, the only
routers in the OSPF domain

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that are putting a
prefix SID into OSPF.

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But that means we
have to configure

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the devices that
we just configured

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to do prefix SIDs as well.

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So let's go ahead and do
that here on router 5.

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So we go back into
segment routing MPLS.

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We go into our connected prefix
SID map for the address family

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IPv4.

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And of course, we want to
advertise our own loopback.

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And we'll just
use an index here.

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We'll make index 5
since this is router 5.

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And we'll exit configuration.

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We, of course, need to do this
on routers 1 and 3 as well.

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So let's go back
over to router 1.

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So back into router
IS-IS 1 for interface

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loopback 0 for our address
family IPv4 unicast.

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And we're going to
assign a prefix SID.

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And again, we'll just use index.

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We'll do index 1.

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Commit the changes.

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And let's see what we've
learned so far from IS-IS.

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Let's do a show IS-IS
segment routing label table.

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What we see here
is we're getting

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prefix SIDs for ourselves,
loopback 0, and routers

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2, 4, and 7, which is correct
because we haven't configured

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router 3 yet.

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So let's go ahead and do that.

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We'll configure router 3.

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Same basic configuration.

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We'll just put it into
IS-IS on this router.

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And this will, of
course, be index 3.

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We verify our IS-IS segment
routing label table.

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Now we see that we have prefix
SIDs for router 1, 2, 3,

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which is, of course,
this router, 4,

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and 7, which are all the
routers in the IS-IS domain.

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So again, the domains
are still separated,

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but within each
domain, the prefix SIDs

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are being propagated.

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Now without the connection
between the domains,

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we can do a limited
amount of testing.

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We could go over to router 7.

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Here we could do a show
MPLS forwarding table.

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We see that we are, in
fact, learning the labels.

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So we could do something, for
example, like trace 10.3.3.3,

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sourcing it from our loopback.

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So we see that's
working as expected.

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We could also trace router 4.

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So we see this is working
as desired as well.

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So the IS-IS domain appears to
be functioning perfectly fine.

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Let's jump over to router 8 and
take a look at the OSPF domain.

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So again, let's do our
show MPLS forwarding table.

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And notice that we have
our adjacency entries

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and we have our prefix SIDs
to get to routers 5 and 6.

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However, notice that all of the
outgoing labels are Pop label.

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Now this is correct for what we
have configured at this point,

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but it's not going to
do us a lot of good

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to trace to router
5 and 6 because we

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won't see any labels anyway.

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They would just be popped,
which means we're not going

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to impose one to begin with.

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So we won't be able to
see labels on this side,

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but just based on this
output, our label distribution

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is working properly
in the OSPF domain.

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So in this video, we
simply enable segment

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routing in our network core.

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Now a lot of the
routers were already

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configured but we took a
look at routers 1, 3, and 5,

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configuring both the routing
protocol to support segment

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routing as well as configuring
our prefix SID for our loopback

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interface.

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Then, of course, we just
did some verification

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to make sure that those
labels are showing up on all

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of the routers appropriately.

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But now it's time to join
our domains together.

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For that, we're going to
be using BGP and PCEP.

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And that's exactly what
we get to configure next.

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Until then, I hope this has
been informative for you,

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and I'd like to thank
you for viewing.

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