Another option we have in stub routing with EIGRP
is the option of using a stub site.
And that's it this video is all about.
[MUSIC PLAYING]
And for this scenario, let's imagine that R6 and R8
are both at the branch office.
So we have Branch 1.
Instead of configuring each of those as stubs, which means
they wouldn't be willing to share information
with each other back and forth-- which might be important,
because we could lose this link here or this link here.
And if we lost one of those links, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And if we lost one of those links,
we'd still like the other side to be able to be used.
So we'd want R6 and R8 to still be able to communicate
with each other.
So the best of both worlds is a stub site.
And what we're going to do is this.
We're going to identify on our 6 that this interface, serial
3/2, is a WAN interface, and that this interface
and this one here on R8 are WAN interfaces.
And with those interfaces identified as WAN interfaces,
we can then configure both R6 and R8
with the same ID as a stub site. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
with the same ID as a stub site.
And they will be willing to communicate
with each other what they learn.
And that way, if this link fails and R8--
it still has connectivity here or here--
is still willing to share that routing information with R6,
where a traditional stub router would not
be passing along that information to anyone.
So the stub site is a solution to this.
And this is a feature that came available at around 15.5
of the Cisco IOS.
So let me share with you the syntax of how to implement this
so you're also aware that a stub site is yet another option
for stub routing with EIGRP. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
for stub routing with EIGRP.
And here is the configuration.
I'm just pulling this straight from Cisco's online doc.
And in configuration mode, we have named EIGRP.
We go to the address family in question.
And here, in the address family for IPv4, we're still saying,
eigrp stub-site with an identifier.
We'll take a closer look at that in just a moment.
Then furthermore, we go to the specific interface
in that address family that's our WAN link.
So for our branch router, and its serial 1/0,
or gig in this case, gig 0/01 that's
the WAN-facing interface, we go to the interface WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
the WAN-facing interface, we go to the interface
within the address family for that specific interface,
and specify stub-site wan-interface.
And regarding this tag, let's go take
a look at the syntax for that.
So here are some options--
really guidelines or ideas--
regarding the formats we could use for those tags
to give them meaning.
Ensure that stub site ID is attached to all the routes that
come in on that WAN interface.
And if we did a show IP EIGRP of the topology,
whether it's for an address family or a VRF,
and looked at that specific route,
it would include that tagged information WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
it would include that tagged information
as part of the information for that route
in the topology database.
And so any routes that come in on those WAN interfaces
are going to have this tag.
And the two routers--
in our case, router 6 and router 8, as they
share routes back and forth--
normally, they wouldn't be so sharing
because they're stub routers.
But they will be sharing these specific routes with that tag,
because they're using the same IDs.
It's like being part of the same team,
and they'll share those routes back and forth.
So in this video, we've taken a look
at an additional way of implementing stub routing,
and that is with a stub site, with the identifier being
configured on the devices at a remote site, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
configured on the devices at a remote site,
including identifying which interface on those routers
is the WAN-facing interface.
So incoming routes, as they come in,
are going to be given those tags and communicated
within that site.
So thanks for joining me in this set of videos.
I'll see you in the very next one.
Meanwhile, I hope this has been informative for you,
and I'd like to thank you for viewing.