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0:00:13
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In our next section here
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0:00:14
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we're going to take a look at the Cisco documentation.
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0:00:17
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There's two different portions we will look at
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0:00:19
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both the technology documentation and the product documentation.
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0:00:24
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Now the first one I have listed here, the technology documentation,
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0:00:28
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will not be accessible to you during the lab exam
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0:00:31
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but it's still a great resource that you can use during your normal preparation process.
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0:00:36
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So if you go to Cisco's main website and go to support and configure
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0:00:42
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then to technology as opposed to products
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0:00:45
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we'll see that there's a lot of good information
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0:00:47
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both frequently asked questions, white papers, and design guides
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0:00:52
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that are published by Cisco about the general technologies
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0:00:55
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and also how they are specifically implemented in Cisco IOS.
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0:01:00
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So let's take a look at this.
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0:01:01
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From Cisco's main website, we'll go to support and configure.
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0:01:09
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Then this page here
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0:01:11
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is what you would see when you're in the lab exam
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0:01:14
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and you open up your web browser.
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0:01:19
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So under the first column we'll check technology
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0:01:24
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then down to the specific topic that we want.
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0:01:27
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So let's say, for example, IP.
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0:01:30
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So under IP we have not only IP routing,
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0:01:34
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which would be things like our IGPs and BGP
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0:01:37
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then Multicast, IPv6, the different applications and addressing services.
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0:01:42
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So let's take a look at routing
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and we'll say OSPF.
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0:01:49
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So from here, sometimes you'll see that the page redirects you.
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0:01:56
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and now we have the IP routing technology support
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0:02:01
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for this particular protocol for OSPF.
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0:02:04
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So if we look at some of the details here
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0:02:07
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the first two we have a technology Q & A
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0:02:10
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for the generic routing protocols for just IP routing in general
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0:02:14
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and then for OSPF.
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0:02:17
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I would highly recommend to read through all of these frequently asked questions
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0:02:22
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for the IGPs, for BGP, MPLS, Multicast, and IPv6.
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0:02:29
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So really the core Layer 3 topics
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0:02:33
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you should take a look for the frequently asked question documents.
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0:02:36
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But if we look at the first one,
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0:02:37
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just the IP Routing FAQ,
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0:02:40
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there's a lot of stuff in here that you most likely already know how it works
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0:02:45
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like what does route summarization mean.
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0:02:48
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Okay, hopefully at this level we don't need to figure out what is summarization.
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0:02:53
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But sometimes there will be a little bit more obscure topics
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0:02:58
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that are not very well explained in other resources
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0:03:01
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but you will see them listed here in the frequently asked questions.
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0:03:06
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So then under OSPF frequently asked questions
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0:03:09
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again, a lot of this stuff hopefully you already know what it is,
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0:03:12
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like I mentioned before,
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0:03:14
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why are loopbacks advertised as /32 host routes
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0:03:18
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or how do I change the reference bandwidth for OSPF.
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0:03:20
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So, this would be how the cost is calculated.
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0:03:24
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But some of this stuff may not be
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0:03:27
|
as straightforward as you might think
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0:03:29
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like does OSPF support the IP type of service based routing.
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0:03:35
|
It says, type of service zero is only supported,
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0:03:37
|
actually that's not what I thought it was.
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0:03:38
|
Let's go back here.
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|
0:03:40
|
Let's say when I have two type 5 links-state advertisements for the same external routing network
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0:03:46
|
in the OSPF database, which path should be installed in the routing table?
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0:03:49
|
I actually did a write up on this just recently
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0:03:53
|
about how the different external path selection works.
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0:03:57
|
It says when you have two type 5 LSAs for the same external networkernal network
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0:04:02
|
prefer the external LSA that has the shortest path to the ASBR
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|
0:04:06
|
and install that into the routing table.
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|
0:04:08
|
Use the show ip capf border-routers command to check the cost of the ASBR.
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|
0:04:12
|
So we will take a look at this design issue when we get to OSPF,
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0:04:17
|
specifically how do we do the E1 versus the E2
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|
0:04:21
|
versus N1 and N2 calculations for external routing
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|
0:04:26
|
but again, these documents, and it probably would only take you
|
|
0:04:29
|
10 or 20 minutes to read through each one of them
|
|
0:04:33
|
so definitely would be useful to look at these for the IGPs, BGP, and then the other main Layer 3 topics.
|
|
0:04:41
|
Okay, also if we go back to the technology documentation
|
|
0:04:45
|
there's things under the white paper categories like the OSPF Design Guide.
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|
0:04:50
|
OSPF version 3 summary, that would be for IPv6 routing.
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|
0:04:56
|
Designing large scale service provider dial networks with OSPF.
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|
0:05:00
|
So you'll see some of these are legacy topics
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|
0:05:03
|
but definitely there's a lot of good general technology information
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|
0:05:07
|
and then also under design
|
|
0:05:11
|
this is what used to be called the Tack Tech Tips.
|
|
0:05:15
|
Now essentially these are individual documents
|
|
0:05:18
|
that show a very specific design
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|
0:05:21
|
and then how you solve it configuration wise.
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|
0:05:25
|
So for example, how OSPF injects a default route into a not so stubby area.
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|
0:05:32
|
So this is different than a regular area versus a stub or totally stubby area
|
|
0:05:37
|
but this type of stuff is not going to be on the regular product documentation.
|
|
0:05:42
|
So again with the technology documentation, you will not have access to this in the exam
|
|
0:05:49
|
but it is a great resource that you can go through during your normal preparation.
|
|
0:05:53
|
So pretty much any topic that is within the scope of the exam
|
|
0:05:57
|
there will be a corresponding technology documentation section on Cisco's website.
|
|
0:06:04
|
Now, the product documentation, this is what we are going to be using extensively during the class
|
|
0:06:09
|
as we go through essentially every single topic.
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|
0:06:13
|
I'll show where that particular topic is located on the documentation CD.
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|
0:06:18
|
And the reason why we need to do this
|
|
0:06:21
|
is that searching of the documentation is disabled during the lab exam.
|
|
0:06:25
|
So you need to know off the top of your head
|
|
0:06:28
|
what is the manual navigation path basically to find everything.
|
|
0:06:34
|
Now in our case there's two main portions that we would go to from the main documentation page,
|
|
0:06:40
|
either to the IOS documentation for 12.4T
|
|
0:06:44
|
or the LAN Switching documentation for the 3560s.
|
|
0:06:49
|
So first, let's talk about the IOS documentation.
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|
0:06:55
|
So let's start back at the main documentation page.
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|
0:07:00
|
We'll go to products, IOS, Regular IOS, 12.4, 12.4T.
|
|
0:07:13
|
Now from this page there's a couple of different places that we may want to go.
|
|
0:07:18
|
In general, there is going to be the configuration guides and the command references
|
|
0:07:25
|
that should have the vast majority of the information that we need.
|
|
0:07:29
|
We'll see the main difference between the two of them
|
|
0:07:32
|
is that the configuration guide gives you a step-by-step list of what you need to do
|
|
0:07:37
|
in order to implement a particular technology.
|
|
0:07:41
|
So let's say like DATP Server.
|
|
0:07:44
|
The DATP Server configuration guide will say you need to enter commands A, B, C, and D
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|
0:07:49
|
in order to get this to work.
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|
0:07:50
|
But you could also use E, F, and G
|
|
0:07:53
|
but that stuff is not 100 percent required.
|
|
0:07:56
|
So what's nice about the configuration guides
|
|
0:07:59
|
if it's some sort of obscure topic that you haven't spent a lot of time with
|
|
0:08:03
|
you can pretty much use what's know as the configuration task list
|
|
0:08:07
|
or their configuration examples
|
|
0:08:10
|
to change around and get a working config for your particular requirements.
|
|
0:08:17
|
Now the command references,
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|
0:08:19
|
this will be used when you know what you are trying to accomplish
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|
0:08:23
|
but you don't know what the particular syntax is
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|
0:08:26
|
or what the arguments are for a particular command.
|
|
0:08:31
|
So let's say we're trying to change the OSPF Hello and Dead timers
|
|
0:08:35
|
but we want to know first off what are the defaults for those.
|
|
0:08:39
|
So we could go to the IP Command reference for OSPF
|
|
0:08:42
|
go to the IP OSPF hello interval and IP OSPF dead interval commands
|
|
0:08:47
|
and it's going to show us what's the usage of the syntax, what are the defaults,
|
|
0:08:52
|
and then was are the details about what this is going to affect when you actually change it.
|
|
0:08:58
|
Now there's also two other important points that we may want to know about the documentation
|
|
0:09:02
|
which are the master index
|
|
0:09:04
|
and the new feature descriptions in the release notes.
|
|
0:09:08
|
Now the release notes, this could be good towards the end of your preparation,
|
|
0:09:13
|
when you're trying to make sure that there's not some major topic that you skipped over
|
|
0:09:18
|
during your studies.
|
|
0:09:20
|
So if we look at what is the latest release,
|
|
0:09:23
|
the latest maintenance release for 12.4T,
|
|
0:09:26
|
it's going to show us what were the particular new features that were implemented in that version
|
|
0:09:31
|
as opposed to the previous maintenance releases.
|
|
0:09:35
|
Okay, so let's go back to the web browser and first we'll start with the configuration guides,
|
|
0:09:44
|
then the command reference.
|
|
0:09:45
|
Now the configuration guides, you can see it's listed right here on the first page
|
|
0:09:49
|
when you click the... when you go to 12.4T
|
|
0:09:54
|
but the command reference is going to be under reference guides
|
|
0:09:58
|
and then here under command references.
|
|
0:10:05
|
Now for both of these the configuration guide and the command reference,
|
|
0:10:09
|
they're all broken down into the different technology subdomains.
|
|
0:10:13
|
So, for example, we see ATM has separate documentation versus Ethernet.
|
|
0:10:19
|
Now, not all of these domains you'll need to know how they work
|
|
0:10:23
|
because for example, ATM is not within the scope of routing and switching.
|
|
0:10:28
|
We'll see some of the other legacy topics like Dial,
|
|
0:10:32
|
whether it's analogy dial or ISDN dial.
|
|
0:10:36
|
That stuff is no longer within routing and switching so we don't need to worry about that documentation.
|
|
0:10:41
|
So the first couple ones, ATM, Carrier Ethernet, Dial VPDN
|
|
0:10:46
|
pretty much you should shouldn't need to reference these for anything.
|
|
0:10:50
|
The next one, Bridging and IBM Networking,
|
|
0:10:53
|
This would be under bridging where transparent bridging
|
|
0:11:02
|
for... let's see if it's still in this document...
|
|
0:11:12
|
configuring integrated routing and bridging, or IRB.
|
|
0:11:15
|
Basically what this feature would allow you to do
|
|
0:11:18
|
is put multiple Ethernet interfaces into the same broadcast domain,
|
|
0:11:24
|
so basically the same VLAN,
|
|
0:11:26
|
and then have a bridge virtual interface or VVI
|
|
0:11:29
|
that is used to route for both of them.
|
|
0:11:33
|
So the BVI in IOS is the legacy version of the SVI, or switched virtual interface,
|
|
0:11:40
|
that we see on the Catalyst IOS.
|
|
0:11:43
|
But the reason that you would want to do this
|
|
0:11:46
|
is that originally IOS supported bridging or routing
|
|
0:11:50
|
but not both at the same time for a particular protocol.
|
|
0:11:55
|
So, for example, you could route IP and bridge IPX,
|
|
0:11:59
|
but you couldn't bridge and route IPX at the same time.
|
|
0:12:04
|
This integrated routing and bridging feature, that's what this introduced,
|
|
0:12:07
|
that you can route and bridge the same protocol stack on the same interface.
|
|
0:12:13
|
So there's some weird designs that you can fix by using IRB.
|
|
0:12:18
|
It's definitely not going to be a very large topic within routing and switching,
|
|
0:12:21
|
but we do need to talk about it to make sure that it is covered in the scope.
|
|
0:12:30
|
Okay. also if we go back to the Dial Technologies,
|
|
0:12:40
|
this is where PPP would be documented.
|
|
0:12:44
|
So configuring Media-Independent PPP and Multilink PPP,
|
|
0:12:50
|
this is where the CHAP and PAP documentation would be for doing authentication.
|
|
0:12:58
|
Or other PPP specific topics like doing address allocation
|
|
0:13:02
|
with IPCP, configuring IP address assignment - that would also be from IPCP,
|
|
0:13:10
|
and then also configuring Multilink PPP.
|
|
0:13:14
|
So the key with this is that it's Media-Independent
|
|
0:13:17
|
so whether you're doing it on a serial link or you're doing it on frame relay
|
|
0:13:22
|
or you're doing it on Ethernet,
|
|
0:13:23
|
all of these options apply to all of them
|
|
0:13:26
|
because PPP is an intermediary encapsulation between your Layer 2 and your Layer 3.
|
|
0:13:34
|
The rest of the stuff here, like configuring SLIP and PPP,
|
|
0:13:36
|
we wouldn't need to do that. That's going to be for legacy Dial applications.
|
|
0:13:44
|
Okay, next we have the IP documentation.
|
|
0:13:46
|
This is where the vast majority of topics that we want to see would be located.
|
|
0:13:54
|
So the first two, addressing and application services,
|
|
0:13:58
|
this is where things like DATP server, DNS server, Network Address Translation,
|
|
0:14:04
|
the First Hop Redundancy Protocols,
|
|
0:14:06
|
so things that are related to IP but not directly to the routing control plane.
|
|
0:14:14
|
So if we look at the addressing services and the application services,
|
|
0:14:19
|
addressing services would be like Network Address Translation,
|
|
0:14:29
|
DACP and DNS.
|
|
0:14:33
|
Also if you look at the first document, Configuring IPv4 Addresses,
|
|
0:14:38
|
there are some very minor features in there that you would want to know about
|
|
0:14:42
|
so I would spend a couple of minutes reading through that
|
|
0:14:45
|
before you get to the exam.
|
|
0:14:47
|
But if we look at any of the individual configuration guides specifically,
|
|
0:14:52
|
let's say, for example, configuring the IOS DHCP server,
|
|
0:14:57
|
as I mentioned before,
|
|
0:14:59
|
you don't need to be an expert in this particular technology for the lab exam.
|
|
0:15:04
|
You just need to have a general understanding of
|
|
0:15:07
|
of what is this designed to do
|
|
0:15:09
|
and how do I get the most basic implementation working.
|
|
0:15:14
|
So again, we should already know what is DHCP, what is a DHCP server,
|
|
0:15:19
|
then we just need to know what's the syntax we need to use
|
|
0:15:21
|
in IOS in order to implement this.
|
|
0:15:24
|
You don't necessarily need to memorize this,
|
|
0:15:27
|
because that's what the documentation is here for.
|
|
0:15:30
|
So for any of these configurations documents
|
|
0:15:33
|
you want to look for the section that says either how to configure XYZ
|
|
0:15:38
|
or the configuration task list.
|
|
0:15:43
|
So in this case it says "How to Configure the Cisco IOS DHCP Server"
|
|
0:15:47
|
if we click on this it gives us a bulleted list
|
|
0:15:50
|
of exactly what we need to do in order to get this working.
|
|
0:15:55
|
So first it says we need to configure a DHCP database agent
|
|
0:15:59
|
or disable conflict logging and this is required.
|
|
0:16:03
|
So this would prevent the router from assigning duplicate addresses
|
|
0:16:08
|
if it didn't know what its previous bindings are.
|
|
0:16:11
|
So let's say, for example, the router leases an address out
|
|
0:16:15
|
but then gets reloaded, it's not going to know about that original lease
|
|
0:16:19
|
unless we have some sort of database that is keeping track of these.
|
|
0:16:25
|
Then the next couple of steps we see are optional.
|
|
0:16:29
|
Then the third one here says Configuring the Address Pool, this is required.
|
|
0:16:34
|
So if we click on this and scroll down a little bit
|
|
0:16:37
|
you can see it gives us the numbered list
|
|
0:16:40
|
of exactly what commands we need to do in order to accomplish this.
|
|
0:16:45
|
So out of here it would be configuring the DHCP pool,
|
|
0:16:48
|
configuring the network, this would be the IP addresses we're actually assigning,
|
|
0:16:53
|
then the different DHCP options like what's the domain name,
|
|
0:16:56
|
what's the DNS server, what's the default gateway - which is default router they're saying here.
|
|
0:17:03
|
Then any other particular option we want to assign,
|
|
0:17:06
|
we can give the particular option number
|
|
0:17:11
|
so we would need to know this in advance.
|
|
0:17:15
|
A good example of this would be if you wanted to tell your IP phone
|
|
0:17:19
|
what is the call manager server.
|
|
0:17:21
|
So you would give it the TFTP option of the call manager
|
|
0:17:27
|
but then you would need to know what that particular number is,
|
|
0:17:30
|
what the option number is.
|
|
0:17:32
|
So stuff like this in the exam,
|
|
0:17:34
|
they're not going to want you to memorize what are all the different DATP option codes
|
|
0:17:39
|
but if you get asked to do a basic server configuration
|
|
0:17:43
|
you should know where this document is located
|
|
0:17:46
|
in order to either use the task list or use their example and change it around.
|
|
0:17:57
|
So again here in the addressing configuration,
|
|
0:18:00
|
this is going to be anything that is directly related to the IPs themself;
|
|
0:18:05
|
so network address translation, DHCP, DNS.
|
|
0:18:11
|
For the application services, this would be stuff like the First Hop Redundancy Protocols,
|
|
0:18:18
|
which are HSRP, GLBP, and VRRP.
|
|
0:18:26
|
Okay, there's also a legacy one there, which is the ICMP Router Discovery Protocol or IRDP,
|
|
0:18:37
|
so you probably wouldn't need to use that
|
|
0:18:40
|
but it doesn't hurt to know what it is.
|
|
0:18:43
|
So it's a pre-DHCP implementation of telling the host what is the default router on the segment.
|
|
0:18:50
|
So there's actually an ICMP type code that you can use to tell the host who the router is.
|
|
0:18:59
|
Then under the Configuring TCP, Configuring IP Services, and the UDP Documents
|
|
0:19:06
|
these are some generic things about IP itself
|
|
0:19:10
|
that you would want to know how IOS implements this.
|
|
0:19:13
|
So if we go like to Configuring TCP,
|
|
0:19:17
|
these would be minor options like how do we do time stamping for TCP.
|
|
0:19:23
|
It says the TCP time stamp option provides improved TCP Round Trip Time Measurements.
|
|
0:19:29
|
because the time stamps are always sent and echoed in both directions
|
|
0:19:32
|
and the time stamp value in the header is always changing.
|
|
0:19:34
|
TCP header compression will not compress the outgoing packet.
|
|
0:19:40
|
So let's say you're trying to check your latency for a particular TCP application.
|
|
0:19:46
|
Let's say you're having latency issues to your webservers.
|
|
0:19:49
|
You could tell the router to do time stamping
|
|
0:19:52
|
then do a telnet to port 80 towards the server
|
|
0:19:56
|
and you would see what are the round trip times for TCP
|
|
0:20:01
|
because this may not be a good test, like if you do an ICMP ping,
|
|
0:20:05
|
it's possible that ICMP could be queued differently than TCP is
|
|
0:20:10
|
so your ICMP round trip time may not accurately reflect what your TCP round trip time is.
|
|
0:20:18
|
So a lot of these are just very minor options.
|
|
0:20:21
|
Configuration wise they're usually just one or two commands,
|
|
0:20:25
|
but let's say like the TCP MSS Adjust,
|
|
0:20:30
|
okay, this is actually a really important command here.
|
|
0:20:33
|
It says when a host (usually a PC) initiates a TCP session with a server,
|
|
0:20:39
|
it negotiates the IP segment size by using the Maximum Segment Size, or MSS, option in the TCP SYN packet.
|
|
0:20:47
|
The value of the MSS is determined by the MTU configuration of the host.
|
|
0:20:51
|
The default MSS value for a PC is 1500.
|
|
0:20:56
|
So for example, if we have our IP Header that is 20 bytes
|
|
0:21:04
|
and we have our TCP Header which is 20 bytes
|
|
0:21:09
|
then the actual payload of the TCP packet, let's say like an FTP session,
|
|
0:21:16
|
would be the MTU minus the overhead for Layer 3 and Layer 4.
|
|
0:21:22
|
So normally your maximum segment size, assuming your MTU is 1500 bytes,
|
|
0:21:26
|
your maximum segment size would be what then?
|
|
0:21:30
|
It would be 1500 minus 40 so it's 1460.
|
|
0:21:34
|
So normally TCP is going to support a payload of 1460
|
|
0:21:38
|
unless you're doing something like giant frames for gigabit Ethernet or 10 gig Ethernet.
|
|
0:21:46
|
Now the reason that we even care about this in the first place
|
|
0:21:49
|
is that if the end host negotiates a segment size that is too large for the transit path
|
|
0:21:58
|
it means that the router would need to do fragmentation.
|
|
0:22:02
|
So any time the router has to do fragmentation
|
|
0:22:05
|
it's going to be a big hit on the CPU especially while we're forwarding a lot of traffic.
|
|
0:22:11
|
So ideally fragmentation should be off loaded to the end host
|
|
0:22:16
|
which is accomplished either by lowering their MTU or by doing what?
|
|
0:22:26
|
By doing path MTU discovery, TCP path MTU discovery.
|
|
0:22:31
|
The problem is sometimes MTU discovery doesn't work
|
|
0:22:34
|
if the transit path is filtering out the ICMP type codes that are needed for that.
|
|
0:22:40
|
So path MTU discovery is going to use ICMP unreachable
|
|
0:22:43
|
which a lot of times for security reasons is filtered out.
|
|
0:22:46
|
So this command here, it says ip tcp adjust-mss.
|
|
0:22:51
|
What this does is it basically gets the router to proxy for the TCP session
|
|
0:22:57
|
and when it sees a SYN packet that is going from the client to the server the client to the server
|
|
0:23:03
|
it's going to intercept this and modify the maximum segment size
|
|
0:23:08
|
to whatever the router has configured.
|
|
0:23:12
|
So the example they're saying here, it says if you're running PPP over Ethernet
|
|
0:23:15
|
your MTU is only going to be 1492
|
|
0:23:18
|
because you have your normal 1500 byte MTU
|
|
0:23:23
|
but then you need an additional eight bytes for the PPP encapsulation.
|
|
0:23:27
|
So the Ethernet payload is reduced from 1500 to 1492.
|
|
0:23:32
|
This means then your TCP segment size at a maximum would be PPP
|
|
0:23:40
|
which is now eight bytes plus IP plus TCP
|
|
0:23:45
|
so these two together are now 48 so we would need to say that it's 1500,
|
|
0:23:53
|
so assuming our MTU is 1500,
|
|
0:23:55
|
we would say 1500 minus 48 so 1452 would then be what our maximum segment size would need to be.
|
|
0:24:10
|
So assuming that your end host cannot properly do MTU discovery
|
|
0:24:15
|
then you can force the router or you can tell the router to force the client to do it
|
|
0:24:20
|
by editing the maximum segment size.
|
|
0:24:23
|
So in production, basically any time you add an encapsulation,
|
|
0:24:28
|
so let's say you're running a GRE tunnel or you're running an IP sec tunnel
|
|
0:24:32
|
maybe both of them, like DMVPN, you would want to use this command on the router
|
|
0:24:37
|
to make sure that the end host is not exceeding the transit path MTU
|
|
0:24:43
|
which means then that the router needs to do the fragmentation.
|
|
0:24:47
|
So if you see very high utilization on the router CPU
|
|
0:24:51
|
that's one of the possible culprits that we're doing fragmentation.
|
|
0:24:56
|
But we'll come back and look at this in more detail when we actually get to PPP.
|
|
0:25:01
|
But it's these type of minor options
|
|
0:25:04
|
that really it's only going to take you 10 or 20 minutes to read through this document
|
|
0:25:08
|
but once you know that that stuff is available
|
|
0:25:10
|
you know where you need to come back to it for a reference in the syntax.
|
|
0:25:16
|
Okay, our next category, IP Mobility,
|
|
0:25:20
|
pretty much we really shouldn't need to do this for mobile IP.
|
|
0:25:28
|
You could look into this.
|
|
0:25:29
|
The configuration is actually not that complicated to implement mobile IP.
|
|
0:25:33
|
It's basically an automatic tunnel from the mobile host to what's known as the home agent.
|
|
0:25:48
|
Then we have Multicast which definitely is going to be within the scope
|
|
0:25:52
|
and the IGP. So EIGRP, OSPF, RIP, On Demand Routing,
|
|
0:25:58
|
where ODR is a way you can encode your routing updates in the CDP packet,
|
|
0:26:03
|
the Cisco Discovery Protocol Packet.
|
|
0:26:08
|
The IPv6 definitely is going to be covered
|
|
0:26:12
|
and it doesn't hurt to read through the bidirectional forwarding detection or BFD configuration guide.
|
|
0:26:18
|
Okay, we'll talk about this when we get to some Layer 2 failure detection cases.
|
|
0:26:25
|
Probably that will be in the miscellaneous topics that we talk about.
|
|
0:26:28
|
The Layer 2 link status is not a good indication
|
|
0:26:32
|
of the end to end reachability condition of the network.
|
|
0:26:36
|
So a quick example of this would be like in DSL.
|
|
0:26:39
|
So from your end host you plug your Ethernet cable into the DSL modem
|
|
0:26:46
|
which is basically a bridge that is bridging between Ethernet and ATM.
|
|
0:26:51
|
So between the CPE device, which is the DSL modem,
|
|
0:26:55
|
and the head end which is called the DSLAN, or the DSL aggregation,
|
|
0:27:01
|
that is basically an ATM PVC.
|
|
0:27:05
|
The reason that this is an issue, DSL from a failure point of view,
|
|
0:27:09
|
is that if the ATM PVC goes down
|
|
0:27:11
|
it's not going to update the Ethernet line protocol status on our side
|
|
0:27:16
|
so the link either from the router to the DSL modem or from the end host to the DSL modem.
|
|
0:27:26
|
So the reason that this is a problem
|
|
0:27:28
|
is that the DSL circuit could be down but we're not routing around it
|
|
0:27:35
|
to an alternate path because the link status did not change.
|
|
0:27:38
|
So we'll look at some cases where we can use
|
|
0:27:41
|
different features like bidirectional forwarding detection,
|
|
0:27:44
|
we could use GRE tunnels, we could use the IPSLA Agreement,
|
|
0:27:48
|
we could use enhanced object tracking.
|
|
0:27:51
|
So I'm not going to go over in detail all the documentations here for BGP and the IGPs and IPv6 and stuff.
|
|
0:27:58
|
We will come back to this when we get to that actual topic
|
|
0:28:01
|
so when we're covering OSPF we'll look at the details of the OSPF configuration guide.
|
|
0:28:06
|
Okay, same with EIGRP, BGP, etc.
|
|
0:28:14
|
Next we have LAN Switching
|
|
0:28:17
|
which would be if you had one of the Ethernet switching modules installed on the router
|
|
0:28:23
|
which is pretty similar to the catalyst IOS
|
|
0:28:26
|
so there's really no reason that you would need to reference that there.
|
|
0:28:30
|
Next one, broadband access aggregation and DSL,
|
|
0:28:35
|
the reason that we would need this is for what?
|
|
0:28:39
|
Does anybody know what's in this category here under broadband access?
|
|
0:28:49
|
This is where PPP over Ethernet is documented.
|
|
0:28:54
|
So under part two, PPPoA, PPPoE, PPPoX, the second sub-document,
|
|
0:28:59
|
providing protocol support for broadband access aggregation of PPPoE sessions,
|
|
0:29:05
|
this is the PPP server, the PPP server document, PPPoE server,
|
|
0:29:15
|
and then you have the PPPoE client.
|
|
0:29:20
|
So you do need to be familiar with both the client and the server configs.
|
|
0:29:24
|
Service selection gateway, really we shouldn't need to look at that.
|
|
0:29:27
|
Multiprotocol Label Switching Configuration Guide,
|
|
0:29:31
|
again, with MPLS, there's actually very little that is within the routing and switching exam.
|
|
0:29:38
|
We are going to cover this in a lot of detail though
|
|
0:29:41
|
because for the vast majority of routing and switching candidates
|
|
0:29:45
|
most people don't have a lot of experience with MPLS previously.
|
|
0:29:49
|
So unless you're already working in a service provider environment
|
|
0:29:52
|
or you have some very large enterprise network you're supporting
|
|
0:29:56
|
maybe like a university network that uses MPLS to segment the management of the traffic
|
|
0:30:02
|
a lot of times people haven't seen this implementation in production yet.
|
|
0:30:07
|
So from here we would need to know the basic MPLS,
|
|
0:30:12
|
like you could read the overview document which is pretty good,
|
|
0:30:15
|
configuring MPLS label switching, really you shouldn't even need to reference this
|
|
0:30:19
|
because when you... Oh, actually this one does cover the routing.
|
|
0:30:30
|
So under configuring MPLS virtual private networks,
|
|
0:30:34
|
it would show you the syntax of the VRF aware routing processes.
|
|
0:30:42
|
So for example, RIP, when we're routing from the provider down to the customer,
|
|
0:30:51
|
the RIP process is going to use the address family
|
|
0:30:59
|
IPv4 VRF under the, under the RIP process.
|
|
0:31:08
|
I don't know what this command is here -
|
|
0:31:09
|
defines the static route parameters for every PE to CE session,
|
|
0:31:14
|
uh, that, oh, that's... okay. That's configuring static routes.
|
|
0:31:16
|
I want to look at, uh, configuring RIP.
|
|
0:31:19
|
Okay, so it says router RIP, address family IPv4 unicast VRF name, then the network statement.
|
|
0:31:26
|
So basically once we get past step two,
|
|
0:31:29
|
now we're running a VRP aware routing process.
|
|
0:31:33
|
Inside there, then we would have the regular, normal RIP commands, like what's the version,
|
|
0:31:37
|
what's the networks we're advertising, what interfaces are passive,
|
|
0:31:41
|
the same as just the regular global routing table.
|
|
0:31:44
|
So this could be a good syntax reference if you forget how to do this implementation
|
|
0:31:48
|
but ideally you should know this off the top of your head.
|
|
0:31:53
|
Okay, we'll see the PE to CE routing syntax is really not that different from the global routing table.
|
|
0:31:59
|
This is something that if you need to look it up
|
|
0:32:01
|
it's basically just going to be a waste of time in the exam.
|
|
0:32:05
|
So the more features that you can get through without having to use the documentation
|
|
0:32:11
|
the more time at the end of the day in the exam that you'll have time to look up the obscure stuff.
|
|
0:32:17
|
So the features and management, maybe security stuff,
|
|
0:32:20
|
that's not really related to the core of the routing and switching in the exam.
|
|
0:32:32
|
Then we have part two, MPLS label distribution protocol, we do need to know how this works
|
|
0:32:36
|
but probably not a lot of the very specific suboptions like session protection,
|
|
0:32:42
|
filtering, what are the labels that can be bound to the different IP routes,
|
|
0:32:48
|
so pretty much probably just this first document which is enabling LDP.
|
|
0:32:53
|
Then MPLS traffic engineering is not part of routing and switching;
|
|
0:32:58
|
neither are Layer 2 VPNs.
|
|
0:33:03
|
So only Layer 3 VPNs and definitely not the InterAS implementations,
|
|
0:33:09
|
so under MPLS Layer 3 VPNs it would just be the basic second document here,
|
|
0:33:15
|
configuring MPLS Layer 3 VPN.
|
|
0:33:20
|
Okay, but we will go over a lot of the details behind this,
|
|
0:33:25
|
things like ensuring that the MPLS VPN clients use the OSPF over the MPLS backbone
|
|
0:33:29
|
instead of through backdoor links.
|
|
0:33:32
|
A lot of the focus we'll see in our MPLS topics
|
|
0:33:36
|
will be how OSPF interacts with the MPLS network.
|
|
0:33:48
|
Moving on here to network management,
|
|
0:33:51
|
NetFlow, IP service level agreement, network management configuration,
|
|
0:33:56
|
most of these documents should be pretty self explanatory what they're covering.
|
|
0:34:01
|
They would not expect you to be an expert in NetFlow or IP service level agreement.
|
|
0:34:07
|
If we look at like the NetFlow configuration guide,
|
|
0:34:10
|
and go to, let's say, getting started with configuring NetFlow,
|
|
0:34:17
|
how to configure NetFlow and NetFlow data export.
|
|
0:34:21
|
It says go to global config
|
|
0:34:26
|
say IP flow-export destination, and then whatever your collection station is,
|
|
0:34:32
|
then at the interface say either IP flow in or IP flow egress.
|
|
0:34:40
|
So pretty straight forward configuration.
|
|
0:34:42
|
We just need to know what is NetFlow to begin with
|
|
0:34:45
|
so it's for collecting traffic statistics for flows that are going through the router,
|
|
0:34:51
|
so transit traffic through the router,
|
|
0:34:54
|
and then we could use this to see like what's the utilization of the link,
|
|
0:34:57
|
what are the different applications that are being used,
|
|
0:35:00
|
so we could see like what's the percentage of web browsing versus bit torrent.
|
|
0:35:06
|
So NetFlow is going to keep those statistics and then send them to the external collection station.
|
|
0:35:12
|
The last one under here, network management configuration,
|
|
0:35:16
|
you see there's a lot of minor features that are covered here like
|
|
0:35:20
|
some of the options with CDP.
|
|
0:35:23
|
This is where the embedded event manager and the TCL,
|
|
0:35:28
|
scripting is covered, then also minor stuff like Sys Log, system logging count.
|
|
0:35:44
|
It says the IOS logging facility allows you to save error messages locally or to a remote host.
|
|
0:35:49
|
When the error messages exceed the capacity of the local buffer,
|
|
0:35:52
|
the oldest messages are removed.
|
|
0:35:54
|
To provide you with more information about messages that have occurred and may have been removed from the local buffer,
|
|
0:35:58
|
an error log count tabulates the occurrences of each error message
|
|
0:36:02
|
and time stamps the most recent occurrence.
|
|
0:36:05
|
Okay, so let's look at their example.
|
|
0:36:07
|
You say logging count, so it's just one command and then show logging.
|
|
0:36:14
|
So stuff like this, there's really not a lot of technology understanding behind it per se.
|
|
0:36:19
|
You just need to know that these features exist.
|
|
0:36:22
|
So once you've read through this document you pretty much never need to come back to it again
|
|
0:36:26
|
unless you get a question about this in the exam
|
|
0:36:29
|
you could come back here and use this as a reference.
|
|
0:36:33
|
The problem becomes if you get questions in the exam
|
|
0:36:37
|
that you have no idea what they're even asking you to begin with.
|
|
0:36:42
|
So let's say, for example, CPU threshold notifications,
|
|
0:36:48
|
it says the threshold notification feature monitors user or notifies users
|
|
0:36:52
|
when a predefined threshold of CPU usage is crossed
|
|
0:36:55
|
by generating an SNMP trap.
|
|
0:36:59
|
So pretty self explanatory what it does here.
|
|
0:37:01
|
If we go over, let's say, 80 percent CPU,
|
|
0:37:04
|
we want to know about this so it's going to send an SNMP trap.
|
|
0:37:07
|
The problem is if I didn't know that the IOS even supported this to begin with
|
|
0:37:13
|
if they as me a question about monitoring the CPU
|
|
0:37:16
|
I'm going to have no idea where to go.
|
|
0:37:21
|
So again, like I mentioned before, there's really no shortcuts to this.
|
|
0:37:24
|
You need to sit down and spend the time to read through the documentation
|
|
0:37:28
|
to figure out what are the particular features that the IOS supports.
|
|
0:37:32
|
The technology stuff that we're going to spend time on like OSPF design,
|
|
0:37:36
|
BGP design, that's what you would not use the documentation for.
|
|
0:37:42
|
So if I need to use the documentation to figure out how does the network statement work in OSPF
|
|
0:37:46
|
it's very unlikely I'm going to be able to pass the exam.
|
|
0:37:49
|
But if I want to know what's the syntax for CPU threshold notificationficaiton
|
|
0:37:53
|
that's really what the documentation is there for.
|
|
0:37:59
|
Okay, there's a question here, where is the NTP documentation located
|
|
0:38:04
|
which is going to bring us to our next portion
|
|
0:38:08
|
of let's say, for example, that we don't know where something is documented
|
|
0:38:12
|
how we could work backwards to figure out where it is.
|
|
0:38:17
|
So most of the rest of this stuff, it's self explanatory what it is.
|
|
0:38:20
|
So QoS is obviously QoS, security and VPN,
|
|
0:38:25
|
secure connectivity, that would be like SSH,
|
|
0:38:28
|
securing the control plane, that would be like control plane policing,
|
|
0:38:32
|
securing the data plane is going to be IP sec tunnels, DMVPN,
|
|
0:38:38
|
that stuff will not be in our scope.
|
|
0:38:41
|
What will be is the firewall feature sets like doing regular ACLs
|
|
0:38:46
|
reflexive access lists, dynamic access lists, content based access control and zone based policy firewall.
|
|
0:38:53
|
Actually, I think technically IPS is in there too, the intrusion prevention.
|
|
0:38:57
|
Okay, so let me close these tabs. Let's say now that we don't know where something is located
|
|
0:39:02
|
like network time protocol for example
|
|
0:39:04
|
and we need to figure out where this is on the documentation.
|
|
0:39:09
|
So from the page here that... actually let me go back one.
|
|
0:39:13
|
Okay, this page is where you would get to once you choose the IOS release 12.4T.
|
|
0:39:20
|
Now I'm going to go to the release and general information
|
|
0:39:25
|
and to the master index.
|
|
0:39:29
|
I want to know what are all the commands that IOS 12.4T officially supports,
|
|
0:39:37
|
so the command master list.
|
|
0:39:39
|
Now I already know what the general syntax for NTP is.
|
|
0:39:44
|
I know that that configuration is going to start with the command NTP.
|
|
0:39:49
|
So if I look under K through O, then I'll just search on this page so I'll hit control F and type NTP.
|
|
0:40:01
|
It says NTP access group and you can see the other options there like
|
|
0:40:08
|
NTP server, NTP peer, and it says that it's under two possible locations
|
|
0:40:16
|
IPv6 page 993 or Network Management page 682.
|
|
0:40:24
|
So as we could probably guess, the first one is going to be for running network time in IPv6
|
|
0:40:29
|
but in this case I want network time for IPv4 so let's open up this second one, NM-686.
|
|
0:40:37
|
It says this is in the network management section.
|
|
0:40:42
|
We can see that at the very top. This is the Cisco IOS network management command reference.
|
|
0:40:48
|
Actually, also right there.
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0:40:51
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So this now means if I were to go back to the configuration guides,
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0:40:56
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I would want to go to network management configuration and NTP should be somewhere in that section.
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0:41:02
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So let's try that. Let's go to configuration guides, network management configuration,
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0:41:16
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and I don't really know where exactly this is
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0:41:20
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so I'm just going to open up all of these subtopics, expand all of them.
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0:41:34
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Then control F and I'll say NTP. Okay, now there's no hits on the page for NTP.
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0:41:40
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What this most likely means is that NTP does not have it's own separate documentation.
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0:41:46
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It's going to be a subsection of something else.
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0:41:49
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So where I would guess is probably going to be under performing basic system management which is the first one.
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0:42:05
|
So it's not under that one. Let's see. Where else could it be here?
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0:42:13
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Configuring network, Cisco network services.
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0:42:17
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It shouldn't be that.
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0:42:24
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It is actually possible that they mislinked the document.
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0:42:29
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Sometimes you'll see when they're moving the stuff around between one version and another
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0:42:34
|
they'll forget to link an individual section
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0:42:39
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but worse case scenario we could go back to, let's say,
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0:42:46
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12.2 mainline or 12.3 mainline and then see what the NTP features are there.
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0:42:52
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So I'm going to guess that the NTP document was mislinked here.
|
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0:42:59
|
So let's try it from 12, uh, let's try 12.2 mainline.
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0:43:06
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Or actually let's try 12.4 mainline. So let's go to the main documentation.
|
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0:43:12
|
Then products, IOS, regular IOS, 12.4, 12.4 Mainline.
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0:43:23
|
Configuration guides, I know it's under network management,
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0:43:28
|
which is under network management, and let's see now, is it under performing basic system management.
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0:44:07
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Ziad here said it's under network management configuration guide release 12.4
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0:44:12
|
performing basic system management setting time and calendar services.
|
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0:44:18
|
So there should be another sub-category under this one then, right?
|
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0:44:23
|
Let's try, let's try back to 12.3.
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0:44:31
|
So in the lab exam, you'll probably have access to all the different versions
|
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0:44:36
|
but you can see this is why you need to spend the time to do this now versus at the lab exam.
|
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0:44:43
|
Okay, so as I mentioned, we're going to be spending a lot of time in class going through the documentation
|
|
0:44:47
|
to make sure we know where all of this stuff is located when we get to the individual topics.
|
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0:44:52
|
Now for the catalyst documentation,
|
|
0:44:55
|
like the regular IOS, it has both the configuration guides and the command references
|
|
0:45:00
|
and the whole entire sections are available in PDF format.
|
|
0:45:05
|
Now I wouldn't necessarily count on this for the actual lab exam
|
|
0:45:10
|
but it's a good resource when you're doing your normal preparation
|
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0:45:13
|
to have everything in one single document.
|
|
0:45:16
|
First because you can search through the entire thing
|
|
0:45:20
|
so if you use whatever your PDF reader's searching feature is
|
|
0:45:24
|
also you could put it on like your iPad or your Kindle or whatever ereader is if you have it
|
|
0:45:30
|
so then it's just one single document.
|
|
0:45:33
|
The IOS documentation you can also do this.
|
|
0:45:35
|
The problem is it's on a per section basis
|
|
0:45:39
|
so if I were to go to 12.4 configuration
|
|
0:45:42
|
then let's say OSPF configuration, configuring OSPF, actually no, it's right here.
|
|
0:45:49
|
It says download the complete book.
|
|
0:45:57
|
Then if you look at the bookmarks for the PDF you can see it's the full section.
|
|
0:46:03
|
So this is useful if you want to search through everything
|
|
0:46:06
|
but you can see in the routers IOS it's on a per topic basis
|
|
0:46:11
|
where for the catalyst switches, if we go to the 3560 configurations,
|
|
0:46:16
|
okay, so let's look at what that path is from the main documentation page.
|
|
0:46:21
|
We'd go to products --> switches --> LAN switches for Access --> Catalyst 3560
|
|
0:46:39
|
then the configuration guides and reference guides for the command reference.
|
|
0:46:45
|
So configuration guides and then I'll pick whatever the latest software release is here, so 12.2(58)SE.
|
|
0:46:56
|
So we can see we can download the full book here which is for all of the configurations.
|
|
0:47:01
|
It's a little bit more convenient than the individual sections.
|
|
0:47:06
|
Now one thing I did forget to mention before we move on to our actual switching discussions
|
|
0:47:12
|
let's go back to the 12.4T documents.
|
|
0:47:23
|
So let's go to products --> IOS --> regular IOS 12.4 --> 12.4T
|
|
0:47:33
|
then to release and general information.
|
|
0:47:38
|
So we saw the master index before, how we can work backwards to the configuration or the command reference
|
|
0:47:43
|
but let's look at the release notes section here
|
|
0:47:47
|
then specifically the new feature descriptions and important notes for 12.4T.
|
|
0:47:55
|
So I don't really care about the platform specific information.
|
|
0:47:59
|
They're not going to test on
|
|
0:48:04
|
They're not going to test on this specific stuff on the exam.
|
|
0:48:07
|
So they try to stay away from hardware and platform specific topics.
|
|
0:48:11
|
What I do want to know is though
|
|
0:48:15
|
what are some of the newer features
|
|
0:48:21
|
And then you can see this listed on a per release basis.
|
|
0:48:26
|
So one that might be important, let's say BGP support for a 4 byte autonomous system number.
|
|
0:48:36
|
So previously the BGP AS numbers were in the range of 1 to 65535
|
|
0:48:45
|
because it was a two byte value.
|
|
0:48:47
|
Now it's four bytes so we separate it into two different sections
|
|
0:48:55
|
like your new AS number would be something like 100:200.
|
|
0:49:01
|
So as of 12.4(24) that should be supported.
|
|
0:49:06
|
Then we see things like DHCPv6 is supported.
|
|
0:49:15
|
A lot of these you'll see are application specific like Voice,
|
|
0:49:20
|
IKE, that's talking about security for internet key exchange,
|
|
0:49:26
|
mobile IP. Here's an interesting one, Multi-VRF selection using policy based routing.
|
|
0:49:33
|
Now, whether this would be in the scope of routing and switching
|
|
0:49:37
|
no one really knows but... where did that go?
|
|
0:49:43
|
Which was... Multi-VRF selection using policy based routing
|
|
0:49:49
|
then this goes to the individual configuration guide.
|
|
0:49:52
|
So you probably wouldn't want to use this during the exam
|
|
0:49:55
|
but to research the features before that it's definitely useful.
|
|
0:49:59
|
So if we look at the overall idea of this
|
|
0:50:03
|
it says the Multi-VRF selection using policy-based routing feature allows a specified interface on a PE router
|
|
0:50:10
|
to route packets to a VPN based on packet length or match criteria defined in an IP access list.
|
|
0:50:18
|
You can do VRF selection by policy routing packets through a route map,
|
|
0:50:21
|
through the global table, or to a specific VRF.
|
|
0:50:24
|
So basically what this means is normally the PE router
|
|
0:50:34
|
connects to the customer edge. Let's say they're using Ethernet.
|
|
0:50:39
|
Normally this is going to be in one particular VRF.
|
|
0:50:42
|
Let's say it's in VRF A.
|
|
0:50:45
|
So all the traffic that is coming in from the customer
|
|
0:50:48
|
it's all going to be using this particular routing table for a routing lookup.
|
|
0:50:54
|
But with policy based routing, you could potentially have a design where maybe
|
|
0:51:00
|
the PE is attached to multiple CEs on the same segment,
|
|
0:51:05
|
so CE2 and CE1 are on the same LAN with the PE.
|
|
0:51:10
|
Then we could say as traffic is received from sources A
|
|
0:51:15
|
put that into VRF A then as traffic is received from VRF B,
|
|
0:51:23
|
or sources B, put that into VRF B.
|
|
0:51:26
|
And one way we could do that is based on policy routing.
|
|
0:51:30
|
So we'd say in a route map, match an access list that specifies sources A
|
|
0:51:36
|
then we set the VRF. Then match sources B, set the VRF to be B.
|
|
0:51:41
|
So typically where you would see this implemented
|
|
0:51:43
|
is in some sort of managed service design.
|
|
0:51:45
|
Let's say you have like a shared office building with different businesses
|
|
0:51:50
|
and someone is doing managed services where they're selling internet access to everyone
|
|
0:51:56
|
but making sure that the individual traffic like from company A versus B stays separate
|
|
0:52:01
|
and one way we could do that is the VRF selection based on policy based routing.
|
