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Introducing Cisco Data Center Networking

This Cisco video training with trainer Anthony Sequeira covers Data Center networking technologies, including topics such as network layer addressing, LAN switching, routing, and more....
This Cisco video training with trainer Anthony Sequeira covers Data Center networking technologies, including topics such as network layer addressing, LAN switching, routing, and more.

Anthony Sequeira guides learners through an introduction to Data Center networking technologies, with a particular emphasis on Cisco technologies. This course prepares learners for the 640-911 DCICN exam, which is the first of two exams required for CCNA Data Center certification.

Note: The exam associated with this course is scheduled to retire on April 4, 2017. Learners should plan accordingly to sit for the exam before its official retirement.

Recommended Experience
  • Familiarity with the Windows or MAC operating system
  • Ability to use the Internet and its related functions such as web browsing and email
Recommended Equipment
  • While no equipment is required for this course, students could benefit from NX-OS access to practice the various commands demonstrated
Related Certifications
  • CCNA Data Center
Related Job Functions
  • Network Administrator
  • Network Engineer
  • Data Center Administrator
  • Data Center Engineer
Anthony Sequeira has been a CBT Nuggets trainer since 2012 and holds a variety of Juniper, Cisco, and Microsoft certifications, including CCIE R&S. His previous Microsoft courses here at CBT Nuggets remain some of the top-rated courses in the library.
 show less
1. Mastering the OSI Model (26 min)
2. Classic Network Devices (16 min)
3. A Brief History of Ethernet (29 min)
4. Characterizing the Data Center Network (18 min)
5. Number Conversion Fun!!! (20 min)
6. Network Layer Addressing (35 min)
7. Subnetting in the DCICN Exam (19 min)
8. The TCP/IP Transport Layer (25 min)
9. The Frame Delivery Process (16 min)
10. Data Center LAN Switching (20 min)
11. Introducing NX-OS Software (23 min)
12. NX-OS Features (17 min)
13. Using the NX-OS (10 min)
14. VLANs in the NX-OS LAN (17 min)
15. 802.1Q Trunks in the Data Center (11 min)
16. VTP in the Data Center?!?! (20 min)
17. Redundancy at Layer 2 (30 min)
18. Routing in the Data Center (32 min)
19. ACLs in the NX-OS (23 min)
20. Introducing IPv6 (9 min)

Mastering the OSI Model


Well hello everyone. Anthony Sequeira here, and it is my great privilege to walk you through CCNA data center here at CBT Nuggets. We're going to get started with this series on 640-911, that's the introduction to Cisco Data Center Networking exam. We're going to have you completely prepared for that exam, but most importantly, we're going to make sure you understand fundamentally data center networking technologies.


In this first Nugget, we're going to get started with the important OSI model. Now typically when an instructor mentions the OSI model, students get up and leave, or if they're watching a computer presentation, they open their email or surf the web. Stay with me people.


This is actually going to be enjoyable. And we're going to do something that a lot of instructors forget to do and that's clearly show you why a mastery of the OSI model is really going to help you with data center networking. I'm not kidding. It's really going to help.


We'll also, obviously, review exactly what this model is. And we've got a bonus in this Nugget, we're going to take a look at a model that actually predates the OSI model and we'll analyze the important TCP/IP model as well. You know, one hero that I've always had in my life is my dad.


When I was a little kid I would watch my dad do something amazing. I would watch him build a house from the ground up. And it was much later in life, like now, that I realized building a house isn't all that incredibly difficult because he did it in modules.


He would first build a foundation. Then after building a foundation, he would go in and he would frame the house. Then after framing the house, he would go in and he would install the electric and the plumbing inside the house. And then he would go ahead and he would do some finish work inside those walls that he had constructed.


And notice my house looks really weird, but anyways, building that complex house in a modular fashion actually makes it much simpler than you might think. This is one of the reasons why we need an OSI model. We need to take something really, really complex, like networking, and we need to break it down into simplified chunks.


And that's one of the things the OSI model brings. Now another important reason the OSI model was invented was because we would have equipment manufacturers, like for instance, how about Digital Equipment Corporation, they would be creating networking stuff and they would be using their own techniques and standards.


And then you would have IBM over here and they're creating cool network gadgets, but they're using their own set of standards and design techniques. And sure enough, the devices would not be able to, what we call, inter-operate. So a nice model that could be used as a guide for networking equipment manufacturers was needed so that this stuff could play together nicely.


Now another reason we might need the OSI model is so that we can accurately teach someone about data center networking. Yeah, if I'm going to teach you a complex subject, I really need to break it down into layers so that we don't get overwhelmed with the subject as a whole.


But I know, I know, I know what you're thinking. You're thinking, Anthony, look, I'm not going to be making networking equipment in my backyard. I'm not going to be teaching this to anyone. Please give me some compelling reason about why I should go through the pain of this theoretical model mastery.


Well let me tell you why-- two big important letters in our world-- TS. What does this stand for? Troubleshooting. We want to master the OSI model because when we're in the data center infrastructure and we must troubleshoot problems, this OSI model mastery can really enhance our troubleshooting skills.


And throughout this CBT Nugget series, I will prove this to you. For right now, you just need to trust me, but you will see how the OSI model can benefit us when troubleshooting. Now what is the OSI model really? Well it's a simple seven layer model that we use for all the great advantages that we've mentioned.


Now the first thing that you're going to want to do for mastery of the model is you're going to want to memorize the seven layers in their order. There's two common ways that you can do this. You can memorize it utilizing a mnemonic device starting from the top and going down to the bottom.


The most popular one in this direction is All People Seem To Need Data Processing. But I don't know about you, I love food. So I like to memorize it from the bottom up with the popular mnemonic device Please Do Not Throw Sausage Pizza Away. Yeah, I really identify with that one.


So no matter how you do it, first step, let's memorize those seven layers. Now let me let you in on a little secret. As a data center networking engineer, you're going to make your money at the lower four layers. Those are the ones that are going to be important to you.


In fact, data center networking engineers typically just say this is L1, L2, L3, and L4. So you won't really hear them say the data link layer. You'll hear them simply say layer two. You might not hear them say the transport layer. You'll hear them say layer four.


So let's keep that in mind, that often the lower four layers, so important to us, are just going to be Layer 1, Layer 2, Layer 3, Layer 4. Hey, I've got a Layer 1 problem. You would know immediately that that person is talking about a physical layer issue.


How does the engineer refer to these layers? Well they'll typically just say, hey, that's an upper layer problem, and oftentimes, this may be a problem in the application itself that is utilized in the data center. And that oftentimes might be someone else's problem.


Now let's zero in on what each of these layers is defining. The physical layer is indeed defining the physical stuff, like a great example of this would be the cabling. Sure, we know we're going to be using technologies in the data center like gigabyte ethernet and fiber channel.


And these technologies are going to be run over physical cables, and this is stuff of the physical layer. I hear some instructors say well, the physical layer is the stuff you can see and touch. Be careful of this, right? Because what about the case of wireless?


Sure, there's going to be a physical layer for wireless, but it's not something that we can see with the human eye. Now what device would you have at the physical layer? We'll talk more in detail about these devices in a later Nugget, of course, but a device that is typical at the physical layer we no longer see in use today and it's a hub or a bit spitter or a repeater.


That's right. In fact, I just thought of another one-- an extender. So hubs, often called repeaters or extenders, are going to be an example of something that works at the physical layer. They are not very sophisticated at all. That's why I love the slang for them of bit spitter.


They're taking in bits, and they're not doing anything sophisticated. They're just spitting those bits out. Now what about the data link layer? What the data link layer is going to be obsessed with getting stuff ready for the physical layer, and taking stuff off the physical layer and moving it up the stack.


One of the other important jobs of the data link layer is to go ahead and start to do some error correction, some error discovery, and it will attempt to correct any errors that are discovered when stuff is going on to the physical or from the physical layer.


Pretty cool. At the data link layer, the devices that are so unbelievably important today are switches. Yeah, switches we are going to be studying in this course quite a bit, specifically, the Nexus. Yeah, the next generation powerhouse switches that are available from Cisco.com.


At the data link layer we have another important technology that's used in ethernet networks and that is a Mac address. Sure, I bet you've heard of this. And in fact, let's jump on to my PC right now and see an example of a layer two or data link layer address in my ethernet network called a Mac address.


So here's the command prompt on my Windows 7 machine. And if I go to this command prompt and say IP config/all, we'll get all these great details about my TCP/IP configuration on the system. Here is my wireless LAN adapter that's built into my laptop.


And look at this, here is the physical address. Let me go ahead and actually show you that. Let me highlight it. So here is the wireless LAN adapter that I'm using, and here is the physical Mac address of that particular system. This is an important Layer 2 or data link layer address that uniquely identifies my system on that Layer 2 network.


How cool? Now let me just warn you that these Layer 2 addresses-- they're 48 bits in length presented in hexadecimal characters but there will be variation in how different computer systems will represent them. So a Windows 7 machine does two hex characters and a dash, two hex characters and a dash.


In a Cisco environment, you might see four hex characters and a period. So just be ready for some flexibility here in how the different devices will portray them. Now by the way, before we leave this focus for now on the data link layer, I want to tell you about another data link layer device.


And it's kind of legacy now. We don't see a much anymore but they were bridges. Bridges predated switches, and they were Layer 2 devices. And they would deal with Layer 2 addresses, but they were just really to bridge or adapt one section of your network to another.


Oftentimes, we might have one type of technology in this part of the network and we needed to bridge it to another type of technology in another part of the network. Now when you tell your friends and family that you are a data center network engineer they are going really be thinking about you in terms of Layer 3.


That's right, the network layer of the OSI model. This is where we have IP living, yeah, the internet protocol, for instance. And we have those Layer 3 IP addresses. This is where devices called routers are operating, right? And these routers in a data center environment they're going to be very large devices.


In fact, let's take a look at one now. Here is a 7700 series 18 slot Nexus. It's actually a switch, by the way, but we refer to it in a multi-layer switch terminology. So I would call this a multi-layer switch. What does this mean? Well we know that a switch is at Layer 2 of the OSI model, but because we say multi-layer, this has the ability to do Layer 3 routing as well.


Look at this thing. Look at all those slots that are modular that would give you the ability to configure this router just the way you need it to be configured for your data center environment. Now when information is coming down from the application layer, or when information is going up the stack, it's the job of the transport layer to decide how this particular information will be transported.


Now there's going to be two options here, right? There's going to be to do this reliably or unreliably. And sure enough, there were two protocols that we'll focus on in this course that are going to decide whether the information is transported reliably or unreliably.


And these are TCP, the transmission control protocol for reliable communications and UDP, the user datagram protocol for unreliable communications. I'll have a Nugget where I elaborate on both of these because I'm sure one of your questions right now is why in the world would I ever want to send something unreliably in the network?


That just doesn't sound smart at all. We'll answer that question and many more when we look at those in much detail later on in the series. Now next up in our stack we have the session layer. The session layer is responsible for just that, creating and managing and tearing down sessions between communicating systems.


Just think about one of the web servers up at Amazon.com. Think of how many different sessions are being initiated with that particular web server. I mean, it's mind boggling. And there needs to be a layer of the OSI model that's going to make sure that these sessions are properly managed.


That's the job of Layer 5. Notice we're now while getting into a discussion of those upper layers which we as data center engineers aren't going to have all that direct involvement with. At Layer 6, the presentation layer, the obsession is formatting of the information that comes down from the application layer so that machines can readily read it.


What would be a great example of a presentation layer technology? How about JPG? Yeah. The standard for photos, for images on computer systems. So the presentation layer-- all about presenting the application layer information. Pretty cool. Then finally, we have the application layer itself.


Good old Layer 7. And you will often hear that layer referred to as Layer 7, by the way. Layer 7 is all about the particular protocols that make networking applications function. Let me give you a classic example, HTTP, hypertext transfer protocol. We know this is the protocol that makes our world wide web functions possible.


Another one would be file transfer protocol. This is a network protocol up at Layer 7 that allows file transfer applications to work their magic. Now when an application up at layer 7 has some data that it's going to send down the stack, as that data-- let's draw that data as a little rectangle here-- as that particular data moves down the OSI stack to be placed on the physical wire or a radio wave, in the case of wireless, as that chunk of data moves down, we have process called encapsulation.


And what's happening with encapsulation is each layer is placing some additional header information onto that data packet. So each one is adding some additional information. We call these headers. And they are going to have important information about functions at that particular layer.


You know what this reminds me of? It reminds me of when the CEO of a company calls in his assistant and he says I need to get this to Bill Gates right away. And he scribbles something down on a piece of paper and hands that piece of paper to his assistant.


She then puts some information on an envelope on that original communication. And she runs it down to the mail room and she hands it to a mail clerk. He puts it in another envelope and puts some addressing information on. And then he goes to Federal Express and they put an envelope with additional information on.


So that original communication from the CEO is at each layer of the communications getting additional addressing information so it can successfully reach its destination. This is the encapsulation process, folks. And you know what, if we have information at the destination moving up the stack, sure enough, this additional information is going to be stripped off as it moves up each layer.


And this process is called de-encapsulation. So we have encapsulation and de-encapsulation which are critical to network communications taking place. Now when you are referring to the information that the application layer sends down, we have a chunk of stuff that we call data.


Yeah, this is the data that we're interested in sending on the network. Now when we have some header information and then the data, we call this a protocol data unit. That's right. This is how we refer to those headers and the data itself. Now there are some names that we give to the protocol data units at the lower four layers of the OSI model.


Remember, we said this is where we're going to shine, this is where we're going to make all our money? By the way, let's back up. Up here at the top, these top three layers, the data and the headers we tend to just kind of a lazily refer to all of that as just data.


But then when we get to the transport network data link in physical, these important lower four layers that we're obsessed with, we give them nicknames. For instance at Layer 4, we call the headers and the data a segment. Yeah. At Layer 3, we call the headers and the data a packet.


At Layer 2, we call the headers and the data a frame. And at Layer 1, we call all of that information bits. Now my friend Darren Dennis, years and years ago, back at a company called Knowledge Net where we worked together and trained online, he invented a great mnemonic for this.


It's Some People Fear Birthdays. I don't. It's weird, but some people do. I don't know. Maybe they're afraid of the candles. So Some People Fear Birthdays is an easy way we can remember segment, packet, frame, and bits. And boy oh boy, if you've been around my training for any amount of time, you'll know that I'm a big stickler about this.


If you're talking to me about the information that your Layer 3 is sending, you better call it a packet. If you're talking to me about Layer 2 transport, you better call that information frames. Yeah, I'm really careful to use the correct terminology because after all, Layer 2 concerns are going to be quite different from Layer 3 concerns.


Now there's another very important point I want to make about this OSI model. And that is the fact that these layers are obviously helping each other, right? They're obviously going to be helping each other. And what's interesting about this is they are indeed unaware of each other though.


For instance, the session layer on one machine thinks it is communicating directly with the session layer of the other machine. It's not really aware of or caring about what's going on down here or up here. So the layers are communicating, in their opinion, with the opposite layer on the other machine.


Pretty interesting and important fact. Now so many engineers out there think this all started with the OSI model but it actually didn't. There was a model invented by the Department of Defense in the United States in the '70s that predated the OSI model and it's called the TCP/IP model.


Notice we need to master the four simple layers of the TCP/IP model. And an easy way to do this and really a necessary thing for you to do is to correlate it to the OSI layers. Notice the data link layer and the physical layer simply become one layer called network access.


The network layer is termed the internet layer. The transport layer is just the same and it's in the same relative location in the stack. And then the application, presentation, and session layers are simply the application layer in the TCP/IP model.


So understand and memorize these four simple layers, and please be able to coordinate them to the OSI. For instance, hey, I know there's a network access layer and it incorporates the data link player and the physical layer. This might be a great time where you should start making some flash cards if you haven't already, either traditional paper based flash cards-- I like to have the muscle memory of writing down information-- or maybe you're fancier and you like electronic flash cards.


Whatever it is, now might be a good time to start because we're already seeing the massive amount of memorization we need to succeed as a CCNA data center. Now for time to time at the end our Nuggets, we'll have a little fun with Exam Time! Yeah, you remember MC Hammer and Hammer Time?


This is Exam Time! And our theme song is [SINGING], enough of that. So anyways, it's exam time. And we're going to take a quick one here. What device operates at Layer 2 of the OSI? And notice in your exam in the actual exam, Cisco will be real great about pointing out to you how many correct answers there are.


If they don't mention this choose whatever, it's just one correct answer, but if they mention it's choose two, choose three, then obviously, we have to select that many correct answers. So what is it, folks? What device operates at Layer 2 of the OSI model?


Is it a hub? Is it a switch? Is it a bridge? Or is it a router? Well we indicated that switches are the Layer 2 devices of our modern data center and we just love them so we'll elaborate on them in great detail on this series. And we said that bridges predate those switches so that's another Layer 2 technology.


So our correct answers are b and c in this particular Exam Time break. By the way, if you're interested in a full practice exam, we'll do a lot of questions together throughout the Nugget series to give you confidence and to discuss the types of questions you'll face.


But if you're interested in a really excellent full blown practice exam for this particular test, just go up to Amazon.com and put in the test number 640-911. And you will see on the first page, you will see an awesome practice exam from my good friend Kevin Wallace over at OneExamamonth.com.


This is the practice exam that I used and I swear by it. It was superb. And I achieved first time attempt success with this particular exam. Notice it's a nice ebook with a nice price tag. So check it out up at Amazon.com, and again, I found that by just doing 640-911 as a search.


So congratulations. You've enjoyed the first Nugget of our CCNA data center series in which we took a look at the why and the what behind the OSI model. We also examined the TCP/IP model which predated this important model. And we know that we need to be able to correlate the OSI model with the early TCP/IP model.


Well I hope this has been informative for you. And I'd like to thank you for viewing.

Classic Network Devices

A Brief History of Ethernet

Characterizing the Data Center Network

Number Conversion Fun!!!

Network Layer Addressing

Subnetting in the DCICN Exam

The TCP/IP Transport Layer

The Frame Delivery Process

Data Center LAN Switching

Introducing NX-OS Software

NX-OS Features

Using the NX-OS

VLANs in the NX-OS LAN

802.1Q Trunks in the Data Center

VTP in the Data Center?!?!

Redundancy at Layer 2

Routing in the Data Center

ACLs in the NX-OS

Introducing IPv6

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Anthony Sequeira
Nugget trainer since 2012