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[AUDIO LOGO]

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Hello, and welcome
to configuring

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route redistribution.

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In this skill, we're
going to be taking a look

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at the process of moving routes
from one routing protocol

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to another, otherwise
known as redistribution.

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Now, we're going to be
focusing on the IGPs

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or the interior gateway
protocols in this skill.

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And the simple reason
for that is we'll

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be doing plenty
of redistribution

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with BGP in our MPLS
skills later in the course.

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So we'll be getting plenty
of practice with BGP.

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Overall, the process is pretty
much the same either way.

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So for the IGPs, we will
be looking at OSPF, IS-IS.

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And we'll actually
look at RIP and EIGRP

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in this skill just
for completeness.

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Now, our main focus
is going to be

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what are the different caveats
of redistributing routes

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into each of the
different protocols.

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And they each do have
their own little caveats.

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So we're going to
take a look at that.

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And we're also
going to take a look

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at how we handle things
like metrics, which we know

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from using
administrative distance,

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are not comparable
between routing protocols.

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Admin distance exists
just because they're not.

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That way, we don't have to
try to compare an OSPF route

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to a RIP route, for example.

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Admin distance just says
to prefer the OSPF route.

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It doesn't try to compare
these two things that are

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very different-- the metrics.

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Well, when it comes
to redistribution,

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we have a similar problem.

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We can't exactly take an OSPF
metric, which is based on cost,

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and put that into RIP,
which is based on hop count.

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And the numbers completely
wouldn't match up.

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So these are some issues
we have to deal with.

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We also have to
deal with the fact

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that as soon as you go between
two different IGPs, well,

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you'll lose the loop prevention
that's inherent to that IGP.

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All of these protocols
have their own unique loop

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prevention mechanisms--

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things like split horizon,
and route poisoning,

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and all sorts of things.

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And of course, OSPF
and IS-IS, both

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being link state
protocols, they're

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naturally, inherently
preventing loops.

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However, when you start
going between areas,

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they have their methods as well.

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But all of this is
going to be lost

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as soon as you start
going between two

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different protocols.

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So we're also going
to have to deal

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with routing loops
or more importantly,

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preventing them from happening.

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So these are the
things we're going

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to be looking at in this skill.

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So as you can hear, we have a
lot of fun stuff to look at.

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So let's jump in
and get started.

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I'll see you in the next video.

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