[MUSIC PLAYING]
So when we were designing this network,
we said right from the beginning that router 1 would
have to be a route reflector, but that we
wanted to see the problem that it created before we actually
turned it on.
Well, in the last video, we just saw the problem
that it creates.
The other routers in AS 65001 are not
getting the prefix that's being injected into BGP on router 4.
So now that we've seen the problem,
let's go ahead and configure router 1 as our route
reflector.
So here on router 1, if we do a show IP bgp,
remember that this router is getting the prefix
from router 4.
This, of course, indicates that router 4 is injecting it
properly, and it's getting to its IP bgp neighbor router 1.
It's just router 1 can't send it to its other IP bgp neighbors
in the AS because it's not a route reflector.
So let's go ahead and configure router 1 as a route reflector.
This is a very easy configuration.
We already have most of the structure here.
We just, of course, have to go back into BGP.
We'll go back into our neighbor group, iBGP_PEERS,
into the address family, and all we have to do
is route reflector client.
We'll commit the change, and exit configuration.
Do note here that the neighbors did bounce.
And this is normal when configuring a route reflector.
So we want to make sure we do this
either hopefully during initial design
and setup of our environment or at least during a maintenance
window if we're turning it on later.
So now, let's go verify that the prefix is showing up on routers
2, 3, and 5 as it should.
We do a show IP bgp.
We see that it now has the prefix from router 4,
router 3 has the prefix from 4, and router 5 has it as well.
So route reflector is working properly.
Let's do a little bit more verification,
let's go back to router 1, let's do a show bgp
neighbor 10.2.2.2, and notice here on the second page,
under address family IPv6 four unicast,
it lists it as a route reflector client.
So we know that router 2 is a client.
Of course, we know that all the neighbors are at this point.
But you can see this in the output of the neighborship.
Also, if we do a show IP bgp for the 100.4.4.0,
also notice that it says here that it was received
from a route reflector client.
And if we go to a device that this prefix has
been reflected to, so let's just use, for example, router 5.
And what we see here is this reflected prefix now
has route reflector attributes on it, the originator
ID, and the cluster list.
Both of these attributes are BGP route reflector loop prevention
mechanisms.
The originator is so if this update were
to get back, in this case, to router 4,
router 4 would be able to look at this
and say, wait a minute, no, no, no.
I originated this, this is a loop,
I'm going to discard this update.
The cluster ID is there to prevent criss cross update
paths if we have redundant route reflectors.
The main idea with that is if we have redundant route
reflectors, we're going to set the cluster ID the same.
We'll be exploring that in the next video.
Now, of course, if we look at this prefix on router 4 itself,
which is originating the prefix, this
does not have any of those attributes
because this is the originating router.
It hasn't been reflected.
These also get removed as soon as we send this
to an eBGP_PEER, including between confederations.
Let's go look at router 7.
Notice here, it has confed external and confed internal
on the two different paths, but what we don't have are
route reflector attributes.
So in this video, we looked at how
to configure a route reflector, which is the easy part.
More importantly, we looked at the route reflector attributes,
how they get carried in the BGP updates, where they are sent
and where they aren't sent, meaning
they're not sent to BGP neighbors or BGP
neighborships even between confederation peers.
So now we really only have one problem
left in our environment, and that
is that router 1 is a significant single point
of failure.
If router 1 goes down, 65.0.0.1 is pretty much not
going to be able to forward anything.
So next, we're going to set up a redundant route reflector.
We'll do that in the next video.
I hope this has been informative for you,
and I'd like to thank you for viewing.