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[music]

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In this section we're going to
take a look at how to manually

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configure IPv6 addresses on your devices.

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We're going to start off with a
base topology I have built here.

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We're going to use this
for most of the course.

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I have some of the addressing done already,

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some of the addressing designed.

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Where we're going to be looking at
right now is going to be on the

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VLAN 36 interfaces between
Router 3 and Router 6.

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It's going to mostly involve
FA0/0.36 on Router 3,

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just to start with for this first section.

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And then we'll move on to assigning
addresses to Router 6 and so on.

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So we're going to start with
manually assigning IPv6 addresses,

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and there's actually quite
a few ways to do this,

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which is why we're going to
take a minute here to do it.

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The first one would just simply
be to type: ipv6 enable.

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So if we switch over here to
the command line, and let me

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hop onto our Router 3, and
we'll say, interface FA0/0.36.

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And just to start with, we'll just
do show ipv6 interface brief.

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And you can see here that
as of right now FA 0/0.36

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does not have any IPv6 addresses on it.

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The first command is just
to simply say, ipv6 enable.

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I think a lot of people misunderstand
this command on the Cisco router,

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that maybe you have to
put it in or something

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like that, and
that's not the case.

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IPv6 enable is a way of
enabling IPV6 on an interface,

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but certainly not the only one.

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What you get if you type ipv6
enable, is you're going to get a

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show ipv6 interface brief, and
you're going to end up with nothing

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but a link-local address on that interface.

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That link-local address is of
course going to be based off of the

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client ID that we discussed earlier,
and that of course comes from,

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if I were to say, do show interface FA0/0,

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and look at the burned
in MAC address on it,

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this is that semi-well-known
formatting - EUI-64 -

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we're going to look at in a minute,

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defaults to using this for the
link-local address, which is, you take

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the second least significant
bit - which is right here -

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of the first byte of the MAC
address and you flip the

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second least significant bit to a 1.

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That's your local global bit
indicating that this address is now

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a global unique address.

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And then, of course, right in
the middle, so in this case

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between the D and the 4 in our MAC address.

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If you look up here between the D
and the 4 up here at this address,

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you insert FFFE to pad
the 24 bit MAC address.

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Sorry, a 48 bit MAC address. Sorry,
up to a 64 bit host portion for IPv6.

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This is done automatically,
and this is functional.

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In fact, just to show you that it works,

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we can hop over to Router
6 and say, interface

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gigabit 00.36, and
say, IPv6 enable.

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Say, do show IPv6 interface brief.

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It also gets an address,
and it's fully functional.

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The only problem is it's a
little bit crazy of an address

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to have to actually try to use.

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So, we can copy it, we can
go to the other side,

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and we can very easily say,
do ping, put that address in,

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and you get the fun first problem that you
have with using link-local addresses.

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And if you look at some of the other
addresses we have on this router already,

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you see here we have a FastEthernet
0/0.344 with an address,

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FA0/1 with an address.

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And notice, with the link-locals, they all
start FE80::/10, as we discussed before.

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So the problem is, of course,
normally a router looks at

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his routing table and says, what
interface does this go out?

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Well, the problem, of course, here
is it doesn't have any idea what

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the egress interface should be.

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And this is just a formatting
thing on the Cisco router,

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but this is another little
bit of a fun thing.

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If you say that the outgoing
interface is FA0/0.36,

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it will actually yell at you here, and say,

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"No, no, no, I want the whole name."

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So FastEthernet 0/0.36, and it works.

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So our link-local addressing works.

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And something else you should note,
it'll become important as we

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move through some of our other modules
coming up later, such as BGP.

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I'll show you how to actually use
the link-local address to peer

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with BGP neighbors and such.

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Problem is, soon as you
use a link-local address,

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like we did right up here, it of
course has no idea what the egress

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interface should be, as
we've already discussed.

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So, for a lot of things, if
you're going to use link-local,

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you need to be able to specify the
egress interface on the same line.

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And you do this by specifying the interface
index number in the IPv6 address.

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Different operating systems
do this different ways.

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If you're on a Windows machine
and - just as an example -

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and you have not turned off IPv6, but
if you're are on that Windows machine

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and you look at your ipconfig, you'll
find that it's usually something

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like a percent 9, something
along those lines.

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But what I'm talking about here
specifically is this part right here.

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Really just the part at the end. I mean
we're going to use the whole address,

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but this tells the router
your egress interface,

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and Cisco chose to just
use the interface name.

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So if I were to repeat my ping command,

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but this time actually add
that to the end of it...

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what sometimes confuses people
a little bit is it's still

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the remote address that I'm trying
to contact, but then after the

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percent is the local egress
interface that I want to go out.

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Hit enter, and it just works.
It doesn't ask me what the

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egress interface is anymore.
The other thing to note here,

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it's a little bit unfortunate, but
I'm sure you probably almost saw

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this coming, is it's case sensitive.
If I lower that just an E

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to a lower case e, it'll tell me "Oh, I
have no idea what you're talking about.

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I've never heard of that address,

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or protocol, or whatever that
is you're trying to say."

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So that's just a little
bit of a gotcha there.

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So that's your IPv6 enable.

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To wrap it up all you do is you
get a standard link-local address

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based off the MAC address of the device.

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Your next choice, of course, is IPv6
link-local with automatic assignment.

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That's what we just looked at, which
is where you just do IPv6 enable.

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This sort of calls into some of the
other stuff I'm going to look at.

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So let's move through a couple of these.

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When we're talking about automatic or
static assignment, this is talking

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about pulling a link-local address
with how you get your address

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with some of the other
things coming up later.

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So, in some of the upcoming lessons

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we will come back and look at this again.

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Basically what I'm just trying to
get out here is you're going to

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get a link-local address no matter how
you get your global IPv6 address.

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We'll see what happens with this
under different scenarios as we

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move forward through these lessons.

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The next one we're going to look at
right now is doing a global address

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with EUI-64, and this is
sort of going to play back

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into these two points above it as well.

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In this one I think a lot of people don't
understand 100% what happens here.

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Let's take a look at it.

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First thing I'm going to do is I'm
going to say, no ipv6 enable.

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Now, we don't have to take this
off, but just in light of what I

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said earlier, that you don't need
it, I just want to show you that

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you, in fact, don't need it.

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As soon as you're going to go in and
start manually doing your own stuff,

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then you don't need
the IPv6 enable anymore.

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That's just sort of a generic way of
quickly throwing IPv6 on an interface.

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Maybe this is like a link between
you and your service provider.

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And as I get into some more
complex examples later,

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I'll probably come back
and just use that again.

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It can be handy, I don't want anybody
to misunderstand what I'm saying.

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It's just that you don't need it if you're
going to set the address another way.

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For example, if I said, do show
IPv6 interface brief, right now.

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We're back to the 36 not having
any address on it at all.

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And now I'm going to say, IPv6
address, and I'm going to give it a

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global address, 2001DB8:100:36::.

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And, normally, of course, in a minute,
we'll put the host portion here.

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What I'm looking at right now is
using an EUI-64 assignment, at which

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case you simply say, the mask, and
then we're going to say, EUI-64.

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Hit Enter, and what you get now,

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do show ipv6 interface brief, is you're
going to get the link-local address,

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because that always comes along.
Have to have the link-local.

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So we get the link-local address
back again, and now it's taking that

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same ending host portion based
on the MAC address and puts it

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after the global address that we put in.

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But I think the part where a lot of
people get mislead here a little bit

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is to say that EUI-64 on the
global address pulls its address

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from the MAC address on the Cisco
router. That's not specifically true.

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That's what I'm going
to show you right now.

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What it actually does is it pulls the
address from the client identifier.

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The client identifier is pulled
from the link-local address.

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The link-local address is defaulting
to pulling that from the MAC address.

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Now, all of that said, I'm
sure you can understand how it

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becomes very common to say
that if you use EUI-64,

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that it pulls the host portion
from the MAC address.

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The problem with that statement is, again,

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it's not completely accurate.

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It's accurate from a default standpoint.

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However, if I were to
say, IPv6 address FE80::,

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and this is Router 3, so
I'll just make it ::3.

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And then I said link-local, to
manually set the link-local address,

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hit enter. Do show ipv6 interface brief.

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What we're going to find is that
not only did that manually set my

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link-local address, it also sets the
client address for the global address.

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So this is what I'm saying
when I say you can't just say

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EUI-64 is based off the MAC
address, and we'll see this

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later when we get to ISATAP tunnels.

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It's not based on the MAC address anyway,

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it's based on the underlying IPv4 address

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of the egress interface for the tunnel.

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So, EUI-64 is not always
based on the MAC address,

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it's actually based on the
client ID for most applications.

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So we'll, again, build on this
more as we go, but this is sort of

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an example of what I meant
when I was talking about,

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you know, if we go back
over here to the slides,

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this is link-local, and how it
behaves and what you can do with

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link-local with either
an automatic assignment,

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which is what we just did.

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That's one way of doing
automatic, just so we're clear.

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EUI-64 is one way of doing that.

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Another way, of course, is to say,
what happens when there's a static

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assignment to the link-local address?

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So that's EUI-64. Let me hop
back over to Router 3 here.

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Now we're going to do it
a little bit different.

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I'm going to say, no IPv6
address FE80::3 link-local.

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And when we look back at it it'll be back
to the MAC-based address thing again.

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And now what I'm going to do is I'm going
to hard code a real global address.

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So we're just going to go back
up to where we said EUI-64.

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First thing we need to do is take that off.

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In fact, you know what, before I do, let's
look at another interesting problem.

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I'm going to actually
hardcode it in an address.

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I believe I mentioned this
in a previous lesson,

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but you really have to be careful
with IPv6 since it does support

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multiple addresses on an interface.

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You can see here what I end up with
is my client ID based address,

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which of course is this one, and
the one I just manually typed in.

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And again, there's nothing
fundamentally wrong with that, unless,

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of course, that wasn't your intention
to end up with both addresses.

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And if that's the case, you have to
go back up to the address that we

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did with EUI-64 and take it off.

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There we go.

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And this goes back to - and
we'll wrap up with this -

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this is a static address assignment.
So this was our last point over here.

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I didn't bring it up there, but this
is an IPv6 global address using

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a static assignment. So it is going to
manually put in our global address,

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like such, and the default behavior--
see, this doesn't go both ways

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like where we're looking at a minute ago.

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If you manually set the link-local,
that will change the global address

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used for any form of automatic assignment.

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In the next section we're going move
into some other ways of assigning

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an address, and what we'll
see there is we can

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control this through link-local as well.

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But if you manually set the global
address or statically set to global,

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that does not affect the link-local.

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Now, since we used the
link-local for so much in IPv6,

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just to leave you with a
recommendation here, I would say,

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ipv6 address fe80::3 link-local.

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00:17:15,099 --> 00:17:20,050
And then what you end up with is
both of your addresses manually

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set the way you want them.

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That's how I would do it if I was going
to do manual address configuration.

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And we are going to leave
Router 3 this way for now.

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[music]