Your final objective in this challenge section is really up to you, and that's to figure out
why we can or can't ping from router 10's loopback addresses to router 1's loopback address.
So if I say trace route to 1.1.1.4, source from, loopback 1, what happens?
Sure enough, we have end-to-end connectivity, but again, it's taking that suboptimal route
down through router 2. Now in the last lab, we fixed that. We did all sorts of traffic WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
down through router 2. Now in the last lab, we fixed that. We did all sorts of traffic
engineering to make it work. So what has broken this time? We got to jump over to router 2 to
find out. Ultimately, if I were on router 2 or router 3, I'm trying to figure out what happened
with that advertisement. Actually, it went from router 4 to router 2, didn't it? So let's do show
BGP IPv4 unicast and see what we have here. All the routes that I have are learned via 2. I don't see WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
BGP IPv4 unicast and see what we have here. All the routes that I have are learned via 2. I don't see
any relationships with 3. Let's look at my neighbor adjacencies. So there's 2, 4. Here's 2, 4.
I'm not seeing any. Oh, there's 3, 4, 3. Okay, so it sees 3, 4, 3. Well, why is router 3 not
advertising up? Let's do show BGP IPv4 unicast. And sure enough, I see the routes that we've WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
advertising up? Let's do show BGP IPv4 unicast. And sure enough, I see the routes that we've
learned via 3, 4. Let's look at the neighbor adjacency. Neighbor 100, 100, 3, 4. And then this
is going to 4 advertise routes. I'm not advertising any prefixes to them. Aha. Okay.
Let's do show IP interface brief. And I want to look at my neighbor adjacency to router 2. WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
Let's do show IP interface brief. And I want to look at my neighbor adjacency to router 2.
Show BGP IPv4 unicast. Let's look again. Summary. Okay, I see my neighbor adjacency here. But again,
no prefixes received. That reminds me of that route reflector problem we ran into earlier.
Let's do show run section BGP on router 2 and see if anything has stopped the ability to reflect WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
Let's do show run section BGP on router 2 and see if anything has stopped the ability to reflect
routes onward. Oh, what do you see right there? Somehow or other, this link got put inside of a
VRF. Now, it does still have this as a route reflector client for router 1, but over towards
router 3. Router 3 is an entirely separate routing table. I show IP route VR, not VRF, VRF WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
router 3. Router 3 is an entirely separate routing table. I show IP route VR, not VRF, VRF
corp. Yeah. So this is an entirely separate routing table. There's no route leaking configured here,
so it's not going to leak routes from the global routing table into the VRF's routing table.
So this is the problem. It's not taking an optimal path because somehow or other,
this particular link, let's do show IP interface brief. This particular link on gig 1 0 must be in WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
this particular link, let's do show IP interface brief. This particular link on gig 1 0 must be in
a VRF. Show run section interface. And yep, right there, gig 1 0 IP VRF forwarding.
So what do we need to do here? We need to get that interface out of the VRF. Let's go into
config T interface gigabit 1 0 no VRF forwarding corp. That should remove this interface from WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
config T interface gigabit 1 0 no VRF forwarding corp. That should remove this interface from
the VRF. I don't know off the top of my head if that's going to make me reset the IP address.
Let's do end, show IP route, show IP interface brief, show IP route VRF corp. We shouldn't WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
Let's do end, show IP route, show IP interface brief, show IP route VRF corp. We shouldn't
have anything in there. Nope, got to spell route correctly though. Still got to spell route
correctly. Nope, still sees that as that link is in the VRF. That's because it's IP VRF forwarding.
Let's go back into interface gig 1 0 no IP VRF forwarding corp. And yep, so it disables that
address and removes. So we do need to set the address back, IP address. That was 172.16.23.2. WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
address and removes. So we do need to set the address back, IP address. That was 172.16.23.2.
255.255.255.0. No shut. Let's go in to our BGP configuration. Do show run section BGP.
So that we can get that because there must be a VRF in the BGP configuration too, WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
So that we can get that because there must be a VRF in the BGP configuration too,
because there was still a peer adjacency. So yep, we got to remove this. So let's go router BGP 100
no address family IPv4 VRF corp. Let's do neighbor 172.16.23.3.
And that is remote AS remote AS 100. Remote WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
And that is remote AS remote AS 100. Remote
remote remote AS 100. Now we have the neighbor adjacency up. So let's go end show BGP IPv4
unicast. And now we're back to seeing our local preferences and weights correctly configured like
we had before. So at this point we should. Nope, still taken the path through to. So show BGP WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
we had before. So at this point we should. Nope, still taken the path through to. So show BGP
IPv4 unicast. Let's look at this from the perspective of router 4. Yeah, I don't see
that advertisement making its way up to router 4 via router 3 yet. Yeah, router 3 is still not
advertising. Oh, I didn't mean to do that. Let's put you back. Router 3 is still not advertising
prefixes when I look at that peer up to router 4. Let's look at the configurations WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
prefixes when I look at that peer up to router 4. Let's look at the configurations
on router 3 and router 4. There we go. Let's also look at it on router 2.
From router 2 perspective, let's see show BGP IPv4 unicast neighbor 172.16.23.3 WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
From router 2 perspective, let's see show BGP IPv4 unicast neighbor 172.16.23.3
advertised routes. Seven routes are being advertised to router 3.
But the next hop is still 12.1. We're not using next hop self. So does R3 have a route to those?
Doesn't look like it. My hunch is that these should be shared via OSPF.
So let's take a look at this show run section router and I'll look at R3's show run section WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
So let's take a look at this show run section router and I'll look at R3's show run section
router. That could be the issue is that R3 doesn't have a valid next hop. Yeah,
that's my hunch right there is that gig 1.0 is not currently active in OSPF. So let's do config
T router OSPF 1. No passive interface for gig 1.0 and loading the full that happened quickly. WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
T router OSPF 1. No passive interface for gig 1.0 and loading the full that happened quickly.
Now if I look at router 3, we have routes. So does router 4 have routes? Let's do
a show. Let's just do show IP route. And we have routes and look at that. Now it's going down WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
a show. Let's just do show IP route. And we have routes and look at that. Now it's going down
through router 3. So now if I trace route, hold your breath. It's going down through router 3.
The optimal path and we have now solved this lab as well. This was a good one because honestly,
I had I didn't know you watch me troubleshoot this live in real time because I know you're
thinking like not she made the lab, but it's like yeah, but like I also didn't realize that
I broke it in this way. So this was kind of fun to actually come through and solve this lab. WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
I broke it in this way. So this was kind of fun to actually come through and solve this lab.
So now we've gone through multiple labs troubleshooting BGP. I hope this has
been informative for you and I'd like to thank you for viewing.