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0:00:14
|
So again, up to this point,
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0:00:17
|
we looked at the configuration of the
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0:00:21
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or the interface
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0:00:23
|
with the variations of the multipoint interfaces
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0:00:28
|
where the multipoint interfaces would
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0:00:32
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for the final destination.
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0:00:35
|
Now, we also have a couple different
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0:00:39
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Both in the IP default gateway and
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0:00:43
|
where the former, the IP default gateway statement
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0:00:50
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So, on the Layer 2 switches,
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0:00:53
|
that don't support IP routing, typically,
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0:00:57
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we could configure this on
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0:01:02
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If we were to turn the
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0:01:04
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For example, on switch 4, if routing is off,
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0:01:12
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the .8 address that's configured
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0:01:15
|
which 2 would have to have the routing process
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0:01:22
|
So, within the scope of the CCIE lab exam, it's
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0:01:28
|
because it means that that particular platform
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0:01:34
|
So, any of the Layer 3 dynamic protocols,
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0:01:39
|
When the routing process is off,
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0:01:42
|
they are not able to do that.
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0:01:46
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Now, if we're doing
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0:01:49
|
and we do wanna
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0:01:53
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but not advertise as
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0:02:00
|
there is a feature known
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0:02:03
|
that when we look
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0:02:05
|
we will see an asterisk
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0:02:10
|
that is considered the
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0:02:14
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Now, the key with this is that it must be
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0:02:20
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So, if it's a class A destination,
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0:02:26
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if it was class B, it's /16.
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0:02:28
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If it's class C, it's /24,
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0:02:31
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and originally, this was for RIP version 1,
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0:02:35
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and for IGRP, because IGRP did not support
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0:02:44
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So, you could technically use this...
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0:02:47
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in your configurations.
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0:02:50
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It just means that
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0:02:53
|
route dynamically, whether it's
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0:02:57
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we can tag as that candidate default.
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0:03:00
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Then, throughout the
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0:03:02
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this is gonna be propagated
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0:03:06
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on a hop-by-hop basis.
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0:03:10
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So, let's say we look at this...
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0:03:14
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in our topology here
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0:03:18
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where we have router 4 that could run RIP
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0:03:26
|
between router 4 and BB3,
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0:03:31
|
this again is the 204.12.10.0/24 network,
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0:03:37
|
and then, we'll also run RIP on our
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0:03:45
|
So, without any special options,
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0:03:49
|
for both of these connected network,
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|
0:03:58
|
So, here on router 4,
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0:04:01
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let's start the RIP process, Router RIP.
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0:04:05
|
This is version 2.
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|
0:04:08
|
We'll have the network 204.12.10.0,
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0:04:12
|
and 155.10.0.0.
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|
0:04:15
|
On the other routers,
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|
0:04:19
|
let's say on router 6,
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0:04:21
|
we'll say, Router RIP Version 2...
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|
0:04:28
|
Network 155.10.0.0.
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|
0:04:34
|
Then, let's also do this one more hop away,
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|
0:04:38
|
So, switch 1, router 6 and router 4,
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0:04:47
|
On switch 1,
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|
0:04:49
|
we need to make sure
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|
0:04:52
|
because again, most of the Catalyst IOS
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|
0:04:58
|
We'll say, Router RIP Version2
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|
0:05:03
|
So, if we were to look at the
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|
0:05:08
|
and we Show IP Route RIP,
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|
0:05:11
|
we could see that
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|
0:05:12
|
some classful networks
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|
0:05:15
|
from the backbone router.
|
|
0:05:18
|
We have the 30.1.0.0.
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|
0:05:21
|
31.0.0.0 etc.
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|
0:05:26
|
Any of these would be valid for...
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|
0:05:32
|
the candidate defaults.
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|
0:05:33
|
Okay, technically, actually,
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|
0:05:39
|
So, the /16, these are subnets
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|
0:05:43
|
learning from the neighbors.
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|
0:05:44
|
But on router 4, if we were
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|
0:05:49
|
IP default-network is 30.0.0.0,
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|
0:05:57
|
then, we look at the Show
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|
0:06:05
|
So, it says, "The IP default-network is 30.0.0.0."
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|
0:06:08
|
If we look at the routing table now,
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|
0:06:16
|
this...
|
|
0:06:17
|
subnet, 30.0.0.0/16
|
|
0:06:21
|
has the asterisk next to it.
|
|
0:06:23
|
This again means that this is the...
|
|
0:06:27
|
candidate default route.
|
|
0:06:28
|
Okay, candidate default-network actually.
|
|
0:06:31
|
If we look at the...
|
|
0:06:32
|
the output, it says, "The gateway of last
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|
0:06:40
|
Normally, when you put
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|
0:06:42
|
it says towards network,
|
|
0:06:46
|
but in this case, we have the dynamic
|
|
0:06:53
|
On a hop-by-hop basis now,
|
|
0:06:54
|
we should the gateway of last
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|
0:06:59
|
based on what the route
|
|
0:07:03
|
So, if we were to
|
|
0:07:07
|
and Show IP Route,
|
|
0:07:14
|
router 6 is the gateway,
|
|
0:07:18
|
The reason why is
|
|
0:07:25
|
auto-summary here.
|
|
0:07:26
|
No Auto-summary.
|
|
0:07:31
|
Because there's actually a difference
|
|
0:07:34
|
6 is learning the classful
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|
0:07:41
|
Where router 4 says,
|
|
0:07:47
|
So, let's disable auto-summary on 4...
|
|
0:07:51
|
and 6.
|
|
0:07:56
|
And then, if we Show IP Route,
|
|
0:08:14
|
we should ideally see here the...
|
|
0:08:17
|
30.0.0.0/16 set as...
|
|
0:08:21
|
candidate default.
|
|
0:08:26
|
So, 6 is not gonna learn this.
|
|
0:08:27
|
The reason why is that I mentioned
|
|
0:08:33
|
The IP default-network,
|
|
0:08:37
|
So, the prefix...
|
|
0:08:40
|
30.0.0.0/16 is not gonna work,
|
|
0:08:45
|
What I'll actually do here...
|
|
0:08:48
|
just for the point of this demonstration.
|
|
0:08:50
|
On backbone 3,
|
|
0:08:54
|
under the RIP process,
|
|
0:09:05
|
so, under router RIP,
|
|
0:09:13
|
And Clear IP Route *.
|
|
0:09:15
|
And the same thing on router 4,
|
|
0:09:17
|
Clear IP Route *.
|
|
0:09:19
|
And Show IP Route RIP.
|
|
0:09:20
|
We should now be receiving...
|
|
0:09:23
|
the classful summary...
|
|
0:09:27
|
of the 30 network...
|
|
0:09:36
|
from the backbone router.
|
|
0:09:37
|
And as we know with RIP,
|
|
0:09:39
|
it is an event-driven process, so it's gonna
|
|
0:09:45
|
This should be less than 30 seconds though,
|
|
0:09:53
|
So, you could technically do this with...
|
|
0:09:56
|
any of the...
|
|
0:09:59
|
any of the routing protocols
|
|
0:10:03
|
But most of the times, there's a simpler design
|
|
0:10:08
|
So, we'll see that when we get
|
|
0:10:12
|
Router 4 should be
|
|
0:10:14
|
Let's look at the Debug IP RIP
|
|
0:10:17
|
to see if it's actually
|
|
0:10:26
|
30.0.0.0/8 came from router 6...
|
|
0:10:33
|
as inaccessible.
|
|
0:10:37
|
I wanna see, am I receiving this from...
|
|
0:10:45
|
BB1. I'm sending updates...
|
|
0:10:56
|
but I'm not receiving updates from...
|
|
0:11:07
|
from BB3.
|
|
0:11:08
|
What I could actually do here...
|
|
0:11:19
|
There's a question, "Maybe I should
|
|
0:11:23
|
Actually, this is probably
|
|
0:11:27
|
and BB3 is running really old-code, so it's not happy
|
|
0:11:33
|
Let's look at Show Run...
|
|
0:11:35
|
Begin Router RIP here.
|
|
0:11:40
|
I wonder if it removed the network
|
|
0:11:47
|
the change here.
|
|
0:11:48
|
And this is a 2500 series routers.
|
|
0:11:52
|
But ideally, what should
|
|
0:11:56
|
this network here... And actually, you know
|
|
0:12:01
|
That prefix list by default,
|
|
0:12:08
|
that's gonna filter out the...
|
|
0:12:10
|
the classful update.
|
|
0:12:12
|
So, as we know, within
|
|
0:12:14
|
you're not gonna be able to make
|
|
0:12:19
|
But just for some of these demos, you may see
|
|
0:12:24
|
If you were to replicate
|
|
0:12:27
|
you could do it internally to the network just by
|
|
0:12:33
|
So now, if I look in the routing table on 4,
|
|
0:12:36
|
now, the classful network
|
|
0:12:42
|
When 4 continues to pass this to 6,
|
|
0:12:51
|
6 should then learn this as the...
|
|
0:12:56
|
default-network as well.
|
|
0:13:00
|
Let's see, Show IP Route RIP.
|
|
0:13:09
|
And let's see, on our next update,
|
|
0:13:21
|
4 is not tagging it as default.
|
|
0:13:24
|
So, let's see on 6.
|
|
0:13:34
|
Now, 6 says this is
|
|
0:13:37
|
But the key here is that it
|
|
0:13:41
|
Then, likewise, 6 should advertise this to...
|
|
0:13:46
|
switch 1, switch 1 doesn't see
|
|
0:13:50
|
Really, it is a legacy configuration.
|
|
0:13:53
|
It was originally designed for
|
|
0:13:57
|
You can still use it, but as you
|
|
0:14:02
|
predictable when we're using
|
|
0:14:05
|
For RIP, if I wanted to
|
|
0:14:08
|
there's much easier
|
|
0:14:11
|
I could simply say, Default Information
|
|
0:14:14
|
Or if I had a static default route,
|
|
0:14:17
|
I could redistribute that in.
|
|
0:14:19
|
Or if I'm learning a default
|
|
0:14:21
|
let's say, maybe BGP,
|
|
0:14:22
|
I could do redistribution of that.
|
|
0:14:24
|
But the default-network
|
|
0:14:29
|
you don't actually
|
|
0:14:34
|
you just tag one
|
|
0:14:37
|
one of your dynamically learned
|
|
0:14:41
|
So, if we look at the Show IP Route,
|
|
0:14:45
|
6 says, "My default gateway
|
|
0:14:49
|
And 4 says, "My default gateway..."
|
|
0:14:54
|
If I Show IP Route.
|
|
0:14:57
|
"My default gateway would be BB3."
|
|
0:15:01
|
So, it's a way to dynamically change the
|