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.
Here's a question for you in this topology which are SPF Rodda types are you able to identify as an
example which rorters in this topology or area border Rodders or a bypass which Rada or routers or backbone
routers which Rada or Rodders or internal routers which Rado or Rogers or ESB Rs or autonomous system
border Rodders.
So in this topology we have EAI GOP running on the left hand side then we have 0 SPF Area 1 0 SPF area
0 and 0 SPF Area 2 and AVR or area border router is a router that has interfaces in multiple areas so
as an example rather three is an area border Rada because it has an interface in Area One and an interface
an area zero root of 5 is an area of border rather because it has an interface in area 0 and an interface
an area to it to is an autonomous system border Roorda because it has an interface configured in a different
routing protocol.
In this case the GOP and it has an interface configured in 0 SPF so write it to as an ESB are were autonomous
system border Radha wrote a three and wrote a five or area border Rodders or a B RS wrote a four is
a back bone Rada or backbone area Rada it is a Rada with interfaces in the backbone area now is can
take on multiple roles so wrote a three and wrote a five are also backbone routers in that they have
interfaces in the backbone or area zero but if you will off to this question I would answer that draw
to three and write a five hour area Border Roads area border Rogers always touch the backbone area virtual
links or out of the scope of the CCMA but I will discuss how to configure virtual links which allow
you to pull or extend the backbone area across another area so area zero would be extended across another
area such as area one to allow an area border rata to have an interface in the backbone area and meet
the criteria that an area of border road must touch the backbone area road a six is an internal radar
it's a Rada with interfaces only in an internal area.
In other words area two.
So now that we know the road types let's configure these rotors these writers have just booted up and
have no configuration
so I'll bypass the initial configuration of the routers so that we can configure them manually so on
rudder one this is the rudder on the left hand side I'm going to configure interfaces in these subnets
as per the diagram as well as configure a loop back on the routers with a IP address of the right a
name.
So this is rather one.
So we'll configure the loop back as follows.
So do show IP interface brief shows us the IP addresses configured on the router now this product will
only run EAI GOP so we'll configure ya job P on this rather.
In this example in autonomous system 100 and I'm gonna configure ya GOP on all interfaces of the router
I'll also turn off automatic summarization so do show IP.
Ya GOP interface shows us that you and your PS enabled on the gigabit 00 interface and the loop back
interface has brought it to configure a hostname of right to go into the gigabit zero interface.
No shut up and give it an IP address of 10 1 1 2 slash 24 mosque interface gigabit 0 1 IP address 10
1 2 1 slash 24 mosque and I'll create a loop back of quadruple 2.
Now this Rada needs to run to writing protocols.
Firstly needs to run job P and I want to enable ya job P only on gigabit 00 so notice the IGP neighbour
relationship has come up so do show IPR GOP neighbor shows us the neighbor relationship to show IP interface
brief shows us that the IP address configured on gigabit 00 is this 10 1 1 2 and do show run pipe section
II GOP shows us that we've only configured EAI GOP on that interface will enable OS SPF in this example
on 10 1 2 1 This is the gigabit 0 1 interface and I'll configure it in Area 1 so to show IP SPF interface
grief shows us that 0 SPF is enabled on gigabit 0 1 in Area 1 and process I.D. 1 process idea was this
no area no we configured over there after a while we'll see the state go to D.R. if we don't configure
rod a 3 quickly but I'm not going to do that right now.
Rider 2 is an autonomous system border rider.
We need to do what's called redistribution from one riding protocol to another.
So basically we need to translate if you like or import routes from one riding protocol into another.
This is very similar to translating a language like French into English or English into Spanish.
We are going to translate routes from one routing protocol into another often as it is in the real world.
When you translate from one language to another you can lose meaning.
So sometimes words in one language don't quite mean the same thing in another language and that's true.
When you do redistribution Yai GOP supports different metrics or different ways of determining the best
route when compared to always P.F..
So when we redistribute GOP into a SPF we can change what's called the seed metric or SPF we'll set
it by default.
We can also change the default cost of a rocket that's redistributed.
Yeah GOP uses bandwidth and delay to determine the best route.
Oh SPF doesn't understand that it only understands bandwidth so you typically need to specify a seat
metric when you redistribute right into a writing protocol.
Oh SPF has a default but notice when we redistribute 0 SPF into EAI GOP we gonna want to specify a metric
and you'll often see the metric written something like this.
So we are taking rights from 0 SPF and advertising them into EAI GOP and we are also advertising rots
from the GOP into 0 SPF.
That's what an area border Roddick does at the moment.
I've only enabled a SPF on gigabyte 0 1 and ya GOP on gigabit 00.
What I'll do with the loop back is advertised that into SPF so I'll advertise this network into 0 SPF.
So now when we use the command show IP SPF database you can see different LSA types in the database.
We've got what's called LSA type 1 or router LSA.
At the moment we only have one product in the database we have LSA type 2 or summary LSA is did make
a mistake here.
And notice I put that interface into area 0.
I actually want to put that in to Area One hence us saying area zero and area 1 in the link state database
7 to remove that from area 0 and put that into Area 1.
So show IP who SPF database.
We only see Area 1 in the database for type 1 and Type 2 aliases Type 1 is once again rather aliases
type 2 or summary aliases and we have what are called Type 5 LSD.
These are rats that came from a different routing protocol.
In other words they were redistributed by an ace PR autonomous system border rider into a waste P.F.
and that's what brought it to is doing in the topology.
So at the moment if we type show IP round we will see the loot back of Route 1 in the running table
as a yard GOP rant and on router 1 we see the loop back of it to advertised into EAI GOP as an external
route it was redistributed from 0 SPF into yo GOP and that's also true for this right.
So those are called external rots.
They came from a different writing protocol.
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