This is one of multiple SPF videos.
I was asked to explain Oh SPF multiple areas and this is one of multiple videos helping explain how
SPF works when you have multiple areas configured so we've now configured rather one and rather two
rather one is once again only running.
Yeah.
GOP as shown here.
Brought it to is running multiple writing protocols so we are running both EAI GOP
and always P.F..
So let me just do that a sure run it's running both yea GOP as well as always P.F. this command redistributes
Oh SPF into each job he or translates if you like oh SPF into E.R. GOP in the same way that you would
translate French into English and it sets what's called the seed metric or beginning metric to try and
set an initial value for the root when it's redistributed.
That's because we have to translate or convert over SPF which only supports bandwidth into EAI GOP which
supports bandwidth and delay as part of its calculation okay.
So let's configure wrote a three I a three in this topology is a area border rather it has an interface
an area one and an interface in areas zero so hostname router 3 interface gigabit 00 no shut IP address
10 1 2 2
select 24 mosque interface gigabit 0 1 no shut IP address 10 1 3 1 slash 24 interface loop back zero
IP address could ripple 3.
Now here's another question for you.
Can you run SPF without a backbone area.
Someone enable a P.F..
I'm only gonna enable SPF on gigabit 00 in Area 1.
Will that work.
Notice neighbor relationship has gone to full.
So show IP SPF neighbor router 3 has a neighbor relationship with Robert 2 and we are receiving always
preference what are called E2 grants or external runs from broader one and we can ping the loop back
of wrought one on rather one debug IP.
Icmp ping that loop back notice we see the echo replies sent from right one back to rather three.
The traffic is definitely getting to write of one.
So this is the thing to remember.
You can and this is not an exam answer.
This is a real world answer.
You can.
Not that you typically want to do it but technically you can run away SPF in an area that's not area
zero.
If this is the big if if you only have one area at the moment it works fine because we only have area
one configured but as soon as we want to configure multiple areas we need to configure the backbone
area or area zero.
So what we'll do now is enable 0 SPF on the loop back in area 0 and on gigabit 0 1.
We'll put both of those interfaces into area zero.
So now show IPO SPF interface brief the loop back and gigabit 0 1 are in area 0 gigabit.
0 0 is an area 1 so that's the configuration of router 3.
What you'll notice as well is Rado 1 running EAI GOP is learning about the loop back of rudder 3 because
router 3 is advertising the loop back to rudder to using a SPF and that's redistributed into EAI GOP
and advertised to run a 1 Okay.
So we've configured router 3.
Now let's configure rudder 4 which has a backbone rather so bypass the initial configuration dialog.
We don't want to configure the rudder that way host strata for interface gigabit 00 no shut IP address
10 1 3 2
so that's the IP address once again interface gigabit 0 1 IP address 10 1 4 1 no shut that credit loop
back.
This is gonna have a slash 32 mosque so do show IP interface breach.
They are the IP addresses configured this road is fairly simple to configure.
All we're going to do is configure OS SPF on all interfaces.
Using this command some simply to enable 0 SPF everywhere.
So show IP of SPF interface brief notice 0 SPF is running on all interfaces of the Rada.
Notice a neighbour relationship was formed to write a three says show IPO SPF neighbor.
We have a neighbour relationship to write a three show IP rort.
We are learning multiple types of OSP France.
We have got what are called intra area routes.
Those are rorts that exist in the local area.
In this case area zero we have what are called into area routes.
Those are routes that exist in a different area and then we have external rots.
Those are routes that originated from a different writing protocol so show IP SPF database will show
us more details.
We have two routers at the moment configured in area zero rudder three and rudder four have interfaces
in area zero.
We have one designated rudder that's rudder three for this link.
We have type three routes.
These are summary link state advertisements or summary LSD so type 1 LSA is a Rada LSA type to LSD are
advertised by designated riders and advertise segments such as the segment 10 1 3 0.
They are type 2 LSD.
These are top 3 LSD or summery LSD.
They advertise rots from different areas into 0 P.F..
We also have a type for LSA.
This is an LSA identifying the autonomous system border rather which is right too.
We don't see this in area 1.
It's a sharpie or SPF database because that road exists in Area 1 but for other areas to get to the
ESB are a summary EPR advertisement is pumped in by the AP are so essentially right 3 is telling rather
for how to get to the autonomous system border rather and then we have what are called Type 5 LSD.
These are LSD that come from outside of our SPF so those rods come from EAI GOP and we can see them
in the running table as this and this the local Rada should be able to ping the loop back of right of
one which it can we can see the debug shown on Route 1 so that's right for configured let's configure
out of 5.
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