Let's understand our lab topology,
at least for this first lab.
I want to stress this right now.
We're using the same topology for all three of our labs
in this series of videos,
but all three of our labs have unique challenges.
Something has broken differently from one lab to the next.
So it is important to, well,
understand what the lab topology is
because you'll use it three times,
but you'll use it three times for three different scenarios.
As you can see, we have four autonomous systems.
We have Autonomous System 100, Autonomous System 200, WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
We have Autonomous System 100, Autonomous System 200,
Autonomous System 300, and Autonomous System 400.
Pretty simple, one, two, three, four, 100.
Now Autonomous System 300 is actually Confederation.
We have Autonomous System 65,100
and Autonomous System 65,200.
The ultimate objective is can we ping
from the loopback one of R10
to the loopback one of R1? WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
to the loopback one of R1?
All of these routes are shared via BGP, allegedly,
but something somewhere is broken.
And then secondly,
does it take the optimal path to get there?
And again, remember BGP doesn't usually
find the optimal path
because it usually doesn't look at things
like link speed in order to get there
unless you're using some sort of underlying IGP
because of the IGP exit metric in the BGP bus path algorithm. WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
because of the IGP exit metric in the BGP bus path algorithm.
In this case, that's not what's going on.
So we have right here from R4's perspective,
we have a fast ethernet link and a gig ethernet link.
Obviously the gig should be the preferred route
going down to R3, then to two, and then to one.
So keep this in mind.
Now addressing schemes,
we probably should talk about this.
When we have a WAN link,
we're looking at the 100, 100s, 100, 200s, and 150, 150s. WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
we're looking at the 100, 100s, 100, 200s, and 150, 150s.
When we have internal links like in AS100 or AS300,
we have internal private address spacing.
So 172.16 here and 10.0 here.
The third octet for each of these is important to know
because this is the router numbers connecting them.
So here is where router two connects to router four.
Here is where router three connects to router four.
Here is where router one connects to router two. WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
Here is where router one connects to router two.
Here is where router two connects to router 11,
two to three, and so on and so on and so on.
So that's really important to understand.
Now the only exception to that
is really right here with router 10.
Didn't really know what to do here,
so we did nine zero because that was router nine
and then router 910 doesn't work.
It's not an available number to use in IP addressing
as you're aware.
So that's the only exception here.
Loopback addresses are just the router number repeated. WEBVTT X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000
Loopback addresses are just the router number repeated.
So 1.1.1.1.
Over here we'll have 10.10.10.10.
So ultimately, can we ping from 10.10.10.10 to 1.1.1.1
and importantly, is it going down the gig link
instead of the fast ethernet link?
That's what this particular lab is all about.