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[AUDIO LOGO]

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Congratulations on
completing another skill.

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Now it's time for a review
in the form of a quiz.

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As we go through
these questions,

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be sure to pause the video after
each question to give yourself

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the opportunity to answer
the question yourself

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before we then go
over the answer.

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That said, let's jump in
with our first question.

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What is the purpose of VRF-Lite?

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Now, this being a fill in
the blanks type question,

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as long as we have
something along these lines,

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it's going to be correct.

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The idea here is that
we can run OSPF in a VRF

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on a device that's not acting
as a PE router, therefore,

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it's not supposed to
be implementing PE loop

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prevention.

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The main purpose
for this, of course,

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is to allow a customer to use
a VRF for their OSPF routing

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for whatever reason
they may want to.

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Next question, what is
the default OSPF cost

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of a SHAM link?

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Now, this could be a little
bit of a trick question

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just because we didn't
point this out specifically.

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However, when we
looked at our routes

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after implementing
the SHAM link,

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those routes had a
cost of 4 or less.

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So that pretty much indicates
that the cost of that SHAM link

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has to be 1.

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And if you think
for just a moment,

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it really does make sense.

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The whole purpose of
building the SHAM link

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is because you want to
use the path through MPLS.

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So if you want to
use the path, you're

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going to want to give
it a very low cost i.e.

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1.

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You would not want to give
it a ridiculously high cost.

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We're trying to use this path.

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So the correct
answer for this is

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number 4, which is a cost of 1.

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Final question, what is the
difference between an OSPF SHAM

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link and an OSPF virtual-link.

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Now, we didn't directly
discuss OSPF virtual links

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in this skill.

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However, you should
already be familiar

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with OSPF virtual links.

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But at bare minimum,
we should be

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able to describe
a SHAM link here.

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So the virtual link is
used to extend only area

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0 through another area.

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The SHAM link, however, is
used to extend any area but not

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through another OSPF area
through our MPLS environment.

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And of course, the
purpose of this

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is to allow those routes to
come through as intra area

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so that we can actually
choose to prefer them

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over maybe something like a
back door or a backup link.

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So that concludes this quiz.

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If you find that you are missing
any of the information needed

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to answer these
questions, I would

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encourage you to go back and
review the referenced sources

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on each question.

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Otherwise, congratulations
on completing

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Implementing OSPF as the CE-PE.

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I hope this has been
informative for you,

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and I'd like to thank
you for viewing.

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