This Flug are you going to continue discussing it.
Mr. distances and the believability of writing protocols.
So on one show I wrote why in this apology is this loop back available in the writing table through
BGP.
And why not for this route.
So this network to dot 2.0 too is available in the writing table and the ront has learnt a viable g.p
this network has learnt of your job.
So why is BGP used for the one network and not the other.
The first thing you need to look at is look at this admin distance here.
Its 20.
So that BGP route has an administrative distance of 20.
What are the administrative distances of BGP and what you must remember is that you have two versions
of BGP BGP and IBG P E BGP has an admin distance of 20 BGP has an admin distance of 200.
So show IP BGP summary.
We have a neighbor relationship to router to as well as two routers three show IP BGP neighbor the relationship
to Rodda to uses IE BGP.
Notice the autonomous system number for oddities to view and scrolling down the neighbor 10 1 to 2 which
is rotted 3 is using BGP router 3 is an autonomous system one.
The relationship is established.
Are we learning the routes through BGP.
So show IP BGP.
Yes we are learning both the loopback of router 2 as well as the loopback of router 3 through BGP.
So BGP has both routes in the BGP routing table but this route is not being put into the IP writing
table and we can see that because of this or it says a rope failure the rope is the wrong information
base which from a CCMA point of view is the writing table.
So this route is not put into the periodic table by BGP and that's because a better route is available
through the GOP.
So 3 3 3 3 and 4 forward and forward for a post not put into the periodic table.
Show IP BGP.
We're not learning quadruple for three BGP.
We are all learning about this route but because of the failure it's not put into the writing table
notice here.
The rot was learned through BGP and the reason why this route is not put into the writing table is because
your job P has a lower administrative distance.
Then I BGP.
So to prove that let's remove your GOP from Rodda one.
So rather no Rodda your GOP one show IP rot.
Notice the rot is now available through BGP had been.
Distance is 200.
So remember IBG has an industrial distance of 200 e BGP has an admin distance of 20.
If we shut the neighbor relationship down neighbor 10 10:01 1 to shut down what we should see is that
the rot is replaced by another writing protocol.
In this case it's always P.F..
So I'm running OSPF and wrote one and wrote it to you and wrote one has learnt about that loop back
through a whisper of previously because the rot was learnt through IBG the BGP rot took precedence.
But now because we've shut down the neighbor relationship OSPF is able to add the rot to the writing
table.
So no neighbor 10:01 want to shut down when that relationship comes up
which it has.
We should see the rot replaced by a BGP rot and we can on this example reap took a long time to converge.
But notice Ripp has been used as the writing protocol to get to this loopback rather than BGP repairs
and Edmon distance of 120 BGP has an admin distance of 200 Ripp is more believable.
So if we removed wrap from the router what we should see is the rot is now available through BGP.
So in summary I BGP has an admin distance of 200 RP has an admin distance of 120.
ISIS has an admin distance of 115 always P.F. has an admin distance of 110 GOP internal Rantz have an
admin distance of 90 static routes to next top addresses have a admen distance of one static route to
directly connected interface has an admin distance of zero.
The lower the number the more believable the running protocol.
Remember with BGP we have both BGP and IBG P E BGP admin distances 20 BGP admin distances 200.
Make sure you know you administrative distances.
Completes this Flug.
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