[AUDIO LOGO]
So now that we have our iBGP peers up and running
in AS 65001 and 65002, now it's time
to get the neighborships up and running
between the confederation ASes.
So this will be bringing AS 65003 in as well,
and this is going to take a few steps.
The first thing we're going to have to do
is teach each of the routers what the overall confederation
AS number is.
In this case, we're going to be using 100.
Then, for the routers that actually
have to peer with another router in a different confederation
AS, we have to tell it that those are other routers,
even though they're in a different AS that
are in the same confederation.
So we're going to have to configure our confederation
peers.
And then, of course, we have to configure
the actual neighborships themselves.
So there's a few steps to this, plus we'll
be bringing in AS 65003 for the first time,
so Router 9 is not even configured yet.
So as usual, let's jump in and take a look at that topology
just so we remember what we're doing
in this video, and then, of course,
we'll jump into the command line and get it all set up.
So what we'll be configuring here
is the connection from R1 to R9, then we'll configure R2 to R9.
R1 is going to be configured with a neighborship to R6,
and R3 is going to have a neighborship to R7.
So those are the things we're going to be focusing on
in this video.
So let's go ahead and jump in.
Once again, we'll just start in AS 65001 with Router 1.
So starting off here on Router 1, we'll of course,
go into our BGP process, and like we said,
there's a few steps.
Router 1, remember, is going to be peering
with Router 6, which is in 65002,
and Router 9, which is in 65003, which
means that we need to tell it that both of those ASes
are confederation peers.
It'll drop us into a subconfiguration mode,
and then we just list out the AS numbers
that we're going to be peering with that we should consider
peers.
The next thing we want to configure
is the BGP confederation identifier.
This, of course, is the AS number
that we're going to be seen as to the rest of the world.
Now, the BGP confederation peers only
needs to be configured on the routers that
are going to actually be having neighborships
with routers in those confederation peer AS numbers.
The BGP confederation identifier really
should be set on every router in the confederation
whether they have peers or not.
That way, everybody knows that they're part of a confederation
and they know what the outside confederation AS number is.
So this should really be set on all the routers regardless
of their peering if they're in a confederation.
So that being the case, we'll end up
just setting this on everything, but certainly here on Router 1.
Next thing we have to do is start
configuring our neighborships.
Now, like we said, these will be two physical addresses.
So 50.0.167.6, that would be Router 6.
That's in remote AS 65002, and we'll
activate the address family.
Next neighbor is 50.1.19.9.
That's Router 9.
It's remote AS will be 65003 and it also
has to have the address family activated.
We'll commit our changes and we'll exit configuration.
That should take care of the configuration on Router 1.
Let's jump over to Router 2.
Once again, we go into the BGP process.
For confederation peers here, Router 2
is only going to be configured to pair with Router 9,
so it doesn't know about 65002.
It only has to know about 65003.
Just to answer another common question I get here sometimes,
first, do I have to list all the confederation ASes here?
And as I sort of just explained, the answer to that is no.
We only have to list the ones that this router itself
are going to be peering with.
Then, of course, the secondary or follow-up question
is usually, but does it matter if I do?
And the answer to that is also no.
If I put 65002 here, it wouldn't hurt anything.
And if I ever did make a peering relationship
to a router in 65002 from here, it would already
know it's a confederation peer.
So there's sort of two different approaches you can take.
Either just list all your Confederation peers
on every router, or just list them as needed as you go.
I'm going to do as needed as you go just to sort of prove
that everything is going to work like this
and you don't have to list all of them on every router.
But again, it wouldn't hurt if you did.
In fact, I a lot of environments that do just that.
But we'll leave it with just the ones we need.
So that means our next command is identifier,
and we know that that's 100.
We'll go back into our address family.
We'll configure our neighbor.
This is going to be 50.1.29.9.
That's Router 9.
It's in remote AS 65003.
We'll enable the address family, commit the changes,
and exit configuration.
Next up, we have to configure Router 3.
Router 3 is going to be peering with Router 7.
Once again, the confederation peers, 65002 in this case.
Again, this one doesn't need 65003.
And the confederation identifier.
Address family.
The neighbor is 50.1.37..7.
Remote AS, of course, is 65002.
Address family IPv4 unicast, commit the changes, and exit.
Now, Router 4 and 5 don't have any peerings,
but again, like I mentioned, they
should at least get the confederation identifier.
So we'll go over to Router 4.
We'll simply set the confederation ID,
commit the changes, and exit.
We'll do the same thing on Router 5.
We'll go into Configuration, and it's the same command here,
and we'll exit Configuration.
OK, so that should take care of 65001.
Now let's jump over to 65002.
We'll start on Router 6.
We'll start by going into BGP.
We'll start with confederation peers.
Here on iOS XE, it's a little bit different.
We put the AS numbers directly on the peers statement.
We don't go into a subconfiguration mode.
It'll just tell us it's an incomplete command
if we try to hit Enter.
So we have to put them on the same line.
In this case, it's 65001.
If it was going to peer with more than one,
you add them to the same line.
If we hit a space, then we hit question mark.
Notice, it's willing to take another as number.
So if we had more than one confederation peer,
we would simply add them on this same line.
In this case, of course, we just have the one,
and then we just have to configure our neighbor
50.0.167.1, which is Router 1.
And, of course, that's in remote AS 65001.
That's why we configured that as a confederation peer.
We'll exit out of configuration mode,
and that neighborship should come up here in just a moment.
So now that our BGP neighborship is up,
let's do a Show BGP Summary.
So we see that that connection to Router 1 is, in fact, up.
It's been up for 16 seconds, but more interestingly,
let's actually do a Show BGP Neighbor for the 50.0.167.1.
So let's look at the details of that neighborship,
and a couple of things we want to take note of here.
The first is that this is still listed as an external link.
So even though it's a confederation peer,
it is still, to a certain extent,
run as an eBGP connection for certain things
like the connection itself.
In other words, the default TTL is one
and it does a connected check, that sort of thing.
So, to a large extent, it is still run as an external link.
Also note that it's saying that the neighbor is
under common administration.
That's your key right there that this is a confederation peer.
So that's the main thing we're looking for.
So now let's go ahead and do Router 7.
Very similar configuration except that this one
is pairing with Router 3.
So we'll go ahead and configure our BGP confederation
identifier and our confederation peer.
And as I'm typing those two commands,
I'm realizing I don't think I put the confederation
identifier on Router 6.
Let's go check.
That's actually pretty far back in our scroll back buffer,
so let's just do a Show Run Section BGP,
and we can see here that, in fact, I did not
set the confederation ID.
So that would definitely be a problem.
Let's go ahead and do that.
And there we go.
Now it's configured.
So now let's go back and finish Router 7.
Sometimes configuring one router will
help you remember that you forgot
to do something on another.
So now we do have our configuration ID and our peer
set.
So now we're ready to configure our neighbor, which
is 50.1.37.3, and again, its remote AS is 65001.
We'll exit configuration, and once again, that neighborship
should come up.
So let's do our Show BGP Summary.
We see that that neighbor is up, and if we
do a Show BGP for Neighbor 50.1.37.3,
we see that once again it's an external link
and the neighbor is under common administration.
So everything looks good here on Router 7.
Let's take a look at this same command, by the way, on iOS XR.
It's pretty much the same output,
but let's just take a look at it so we've seen it.
We'll just look at Router 3 since we just
configured Router 7.
So here we'll do the Show BGP for neighbor 50.1.37.7, which
is Router 7, and as we see here, it again lists it
as an external link, and we see that same statement
that the neighbor is under common administration.
So iOS XR is listing this the same way.
So now that our two neighborships
are up between routers 6 and 1 and 7 and 3
between AS 65001 and 65002, our final step
here is going to be to configure Router 9 and get AS 65003 up
and running with neighborships to both Router 1 and Router 2.
So let's jump over to the command line on Router 9 next.
So we start this up as AS 65003.
Now, this is the first we've configured Router 9,
so we're going to go ahead and set its router ID as well.
Set the confederation ID.
We'd better do that first since we can
see I'm prone to forget that.
Confederation peers.
And again, this one only has to pair with 65001.
Then we'll set up our neighbors.
So it's 50.1.19.1.
That's Router 1's connection.
It's in Remote AS 65001, and we have Neighbor 50.1.29.2 also
in 65001.
We'll exit Configuration.
We can see Router 2 came up already and there's Router 1.
We do our Show BGP Summary.
We can see both of those have been up for 9 and 11 seconds
respectively.
I don't think we need to look at both of these here,
but if we do a Show BGP Neighbor and we just
pick on one of them, 50.1.19.1, just look at Router 1,
we can again see it's an external link
and it's under our common administration.
So we know that it's configured as a confederation peer
and the neighborship is up.
So in this video, we configured our neighborships
for the connections between our different ASes
inside of our confederation.
The big things to remember here is
we had to set the confederation identifier,
clearly something I need to remember,
and we had to set the confederation
peers so that the routers would know,
yes, it's an eBGP connection sort of,
but it's between confederation friends
so we run it just a little bit differently with respect
to things like AS path and passing local preference
and things like that.
So we got these confederation peers up and running.
Of course, now we have to bring in our external neighbors
and bring some networks into our BGP environment,
and that's exactly what we're going to do in the next video.
So I'll see you there.
I hope this has been informative for you
and I'd like to thank you for viewing.