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Cisco CCNA certification proves your professional worth. It tells prospective employers that you can handle the day-to-day work of running a mid- to large-sized Cisco network....
Cisco CCNA certification proves your professional worth. It tells prospective employers that you can handle the day-to-day work of running a mid- to large-sized Cisco network.

The two-exam CCNA process covers lots of innovative features, which better reflect the skills and knowledge you'll need on the job. Passing both exams is your first step towards higher-level Cisco certification, and trainer Jeremy Cioara has mapped these CCNA training videos to the 640-816 test. This CCNA training is not to be missed.

Here's how one user described Jeremy's training: "By the way, Jeremy Cioara has to be by far one of the BEST Cisco trainers I have ever had the privilege to learn from overall. He not only keeps your attention but his energy is contagious and he provides the information at a level where you grasp it rather easily."

The last day to take the 640-816 exam is Sept. 30, 2013. After that date, the only ICND2 exam available will be 200-101. CBT Nuggets has a training course for the 200-101 exam here.

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1. Review: Rebuilding the Small Office Network, Part 1 (33 min)
2. Review: Rebuilding the Small Office Network, Part 2 (28 min)
3. Review: Rebuilding the Small Office Network, Part 3 (23 min)
4. Switch VLANs: Understanding VLANs (16 min)
5. Switch VLANs: Understanding Trunks and VTP (39 min)
6. Switch VLANs: Configuring VLANs and VTP, Part 1 (35 min)
7. Switch VLANs: Configuring VLANs and VTP, Part 2 (39 min)
8. Switch STP: Understanding the Spanning-Tree Protocol (28 min)
9. Switch STP: Configuring Basic STP (21 min)
10. Switch STP: Enhancements to STP (29 min)
11. General Switching: Troubleshooting and Security Best Practices (29 min)
12. Subnetting: Understanding VLSM (18 min)
13. Routing Protocols: Distance Vector vs. Link State (26 min)
14. Routing Protocols: OSPF Concepts (30 min)
15. Routing Protocols: OSPF Configuration and Troubleshooting (39 min)
16. Routing Protocols: EIGRP Concepts and Configuration (32 min)
17. Access-Lists: The Rules of the ACL (27 min)
18. Access-Lists: Configuring ACLs (34 min)
19. Access-Lists: Configuring ACLs, Part 2 (48 min)
20. NAT: Understanding the Three Styles of NAT (20 min)
21. NAT: Command-line NAT Configuration (35 min)
22. WAN Connections: Concepts of VPN Technology (33 min)
23. WAN Connections: Implementing PPP Authentication (34 min)
24. WAN Connections: Understanding Frame Relay (28 min)
25. WAN Connections: Configuring Frame Relay (30 min)
26. IPv6: Understanding Basic Concepts and Addressing (34 min)
27. IPv6: Configuring, Routing, and Interoperating (23 min)
28. Certification: Some Last Words for Test Takers (13 min)
29. Advanced TCP/IP: Working with Binary (25 min)
30. Advanced TCP/IP: IP Subnetting, Part 1 (55 min)
31. Advanced TCP/IP: IP Subnetting, Part 2 (22 min)
32. Advanced TCP/IP: IP Subnetting, Part 3 (19 min)

Review: Rebuilding the Small Office Network, Part 1

Review: Rebuilding the Small Office Network, Part 2

Review: Rebuilding the Small Office Network, Part 3

Switch VLANs: Understanding VLANs

Switch VLANs: Understanding Trunks and VTP

Switch VLANs: Configuring VLANs and VTP, Part 1

Switch VLANs: Configuring VLANs and VTP, Part 2

Switch STP: Understanding the Spanning-Tree Protocol

Switch STP: Configuring Basic STP

Switch STP: Enhancements to STP

General Switching: Troubleshooting and Security Best Practices

Subnetting: Understanding VLSM

Routing Protocols: Distance Vector vs. Link State


Now we'll begin our next major section of technology, which is routing protocols at the ICND2 level. Back in ICND1, all we really discussed was RIP because that's the basic routing protocol you can use to get a small network running. As we move into ICND2, we'll move in to some of the more advanced protocols such as OSPF and EIGRP. But


before we begin, we need to understand some foundation concepts and hit a little review from ICND1 as we discuss distance vector versus link state routing protocols. This is a big class difference of routing protocols. Distance vector was what we saw on the ICND1, and now we're going to move into link state in ICND2. We'll first look at what distance vector routing protocols are all about and talk about some of their drawbacks.


When we were in ICND1, we talked about RIP, and we said this is what it does, but we really didn't see the dark side of the RIP protocol. That's what we'll look at as we see the loop prevention mechanisms. We'll then move into the link state routing protocols and what they're all about.


We'll first start off with a little bit of review from the ICDN 1 world, as we talk about the two umbrellas of routing protocols that exist: distance vector and link state. These two umbrellas really mark a big divide between the styles of routing protocols, and the best way I can compare them is to talk about my first car. My first car was a 1982 Volkswagen Rabbit diesel model. Now, nowadays, I look back and I think, man, I wish I had that car because gas prices are so high, and I think I got around 50 miles to the gallon. It was insane. But back when I was 16 years old and in high school, I didn't appreciate the car. I thought,


this car is not a babe magnet, because that's, that's you know, admittedly, that's all you're really looking for at the high school-age, is just the cool car. And that car lasted me for years. As a matter of fact, I sold it when I had 200 and 200,000 miles on it, and it was still running. I never changed the oil; I just put gas and I never did any maintenance at all. It just kind of went. The drawback to the Volkswagen Rabbit,


besides the babe magnet factor, was the speed. I timed it once. You know to a high school male person, as myself, the 0 to 60 time of your car is very important - to see how fast you can move. And I timed it, and that car got 0 to 60 in 42 seconds. I still remember it; to this day I thought, how horrible! But that's what distance vector routing protocols are all about. They're extremely easy to configure.


Meaning, just like my car, it didn't really take much to get in there. Although, I had to learn to drive stick shift and what glow plugs were all about. You just kind of turn them on, and they work and you don't need to maintain them - they just keep running. The


problem with them is they're not very fast, and they don't have many features. The two examples of distance vector routing protocols are RIP and IGRP. The RIP protocol we set up in ICND1. IGRP is gone. CISCO has officially discontinued support for IGRP, it's not even in the newer IOS versions. That's because nobody really used it.


They moved on to link state. Now, that is the Dodge Viper, the screaming fast car that takes just a ton of cost to get running, meaning a lot more knowledge to run that car than just a Volkswagen Rabbit, and there's a lot of maintenance and tuning and tweaking that has to go into it. And in the same sense, with link state routing protocols


they're very difficult to configure. As a matter of fact, we're going to get into the OSPF protocol and talk about configuring and we'll even set it up, but to really fully understand OSPF that's what the CCNP courses are all about. The BSCI focuses tons of information on OSPF that expands on what we're going to lay as the foundation here. So they are feature-riffic;


they have a lot of stuff that they're able to do and a lot of speed criteria that they can handle. And the two examples are OSPF and IS-IS. IS-IS was the routing protocol for the OSI protocol. A lot of people just think OSI was a model, but there is an OSI protocol that is out there and it's even better than TCP/IP, but not many people use it.


Now down at the bottom, you see the HYBRID and this is the Dodge Viper Rabbit if you will. It's the best of both worlds, really easy to configure but gives you all the features of a link state protocol. The Achilles' heel of this hybrid routing protocol


is that it is proprietary, and the one example of it is EIGRP. CISCO made it and only CISCO runs it, so you have to have CISCO routers everywhere to support that protocol. Let's first focus on distance vector routing protocols in their simplicity and in such a way that we can see some of the weaknesses that were not exposed in ICND 1. Distance vector routing protocols by nature send their entire routing table at specific intervals. The one protocol that's left, which is RIP,


sends its entire routing table once every 30 seconds. So you can think of it as - imagine, imagine yourself standing in front of a big room of people, and you step up to the microphone every 30 seconds and say, "Hello everybody in this room, I know about,2.0,3.0,4.0." And then you go and take a seat and wait 26 more seconds and walk back up to the microphone, (it's been that 30 second interval), and you say, "Hello everybody, I know about,2.0,3.0,4.0." And so on, and then you sit back down. That's


exactly what RIP is doing. It's broadcasting or multicasting, depending on the version you're using, to the entire network once every 30 seconds to let them know what it knows about. So if we're running RIP down here, I have a interval once every 30 seconds, I'm saying, hello everyone out both interfaces, I know about,2.0,3.0 and 4.0. Now, this router over here gets it, and says, oh great, well I knew about two, but I didn't know about one, so I'll add that to my routing table. It's a little review in, in, from ICND 1, how routing tables are built. And so, before long all these routers know


about their routing table. Now keep in mind, the reason that RIP sends updates every 30 seconds is not just because these routers might have missed something, it's because its update system is the only keepalive it has. Meaning, if this router stops hearing updates it's going to realize, oh well, this router over here, (we'll call them router C), is dead. So, I will see if I have backup routes to reach


the network that router C was being used to support. So, those updates are keepalives, and in their simplicity, RIP or distance vector protocols have looping issues. Here's what that means: Let's imagine that router C over here has, you know, sent out its update. It's doing the normal RIP thing, and, you know, over


here is the building that it's supporting, we'll say it's in Arizona, and that's the network. And the IT admin in Arizona comes in. It's seven in the morning, you know, he just happened to beat rush-hour so he came in a little early. And that, that, the administrator is


walking up into the IT room. Just got his cup of coffee, you know, (slurp), sipping the coffee and just you know, trying to wake up. Network admins are not morning people. They are creatures of the night because that's when most of your maintenance Windows are happening. And he


walks up, (trot,trot,trot,trot,trot), sees this dangling cable, but sees it too late. Trips over this Ethernet cable connecting the router to the switch and the rest of the network over here. And you know, severs the cable, (snap!), and sparks are flying and fire extinguishers. It's not that bad. But, either way,


router C loses its connection to the network. Now, unfortunately, router C just sent an update two seconds ago, so it's got 28 more seconds to go before it sends out its next update and lets everybody know that the network is down. Well, here's where the problem comes


in. Router B just happened to send out its last update five seconds or sorry I should say, 25 seconds ago, so it's got five seconds left until its next update. "Hello everybody, this is router B now, I know about,3.0,2.0 and 1.0, (chrk,chrk,chrk,chrk,chrk). That update hits router C. Router C gets it and goes, "That's, that's fantastic. Router B, you must


have been reading my mind because I just lost my ow- my own connection to It just went down. So, what I'll do is I'll point to you as the next hop address. We'll say router B is over here. So router C will point to router B as the next hop


address to now reach Now, you and I are looking at this diagram going, why are you doing that router C, what are you thinking? Don't, no, don't do that. Router B was using you to get to the network. Why, why would you try and use router B? But, unfortunately, distance vector routing protocols aren't that smart, so router C points to router B to reach the network, and 28 seconds later sends out its own update saying, Hey, I now have a new path to get to It is through router B. That's, that's the way that I go, and it's two hops away from me. Now, let's check this out. Before, router C was directly


connected, so it was zero hops - that's RIP's metric, it's, it's hop count. So it was directly connected zero hops. So for router B, it was one hop, meaning router B would go- ta,ta,ta,ta,ta- hop, router C and I'm there. That, that was the process router B would use, but now router B sent an update to router C saying I have a link to, and it's one hop away from me. Router C got that update and says, well, if it's one


away from you, and I go through you to get there, it must be two hops away from me. Does that make sense? Because router C thinks, I hop through router B and then go wherever router B goes and then I'm there. So router B gets the update, right? Says, Ok, now I am hearing about from C. And C is now claiming that it's two hops away. Router B is scratching its


head and goes, well, that's funny. It used to be zero hops away from router C, but now it's two, so, well, I guess if it's two hops away from router B, it must be three hops away from me, because I use router- oops, I meant router C- if it's two hops from router C, it must be three from me, because I use router C to get there. That's odd. And it passes that update to router A over here,


and router A gets it and says, well, that's funny, it used to be two hops for me, but I guess now that it's three hops from you, it must be four hops from me. And this system goes round and round and round and round and round. And these hop counts keep going up, higher and higher and higher. This is known, its symptom is technically called


a countdown to infinity. Now, you and I know you'll never reach infinity, and that's why we call this an official routing loop. This is something that distance vector routing protocols, such as RIP, can experience. Thankfully, built-in to CISCO routers are five loop prevention mechanisms to keep what I just showed you from happening. Now


this will prevent every routing loop that you can have. So that leads to the question, or begs the question, why do we need to know about these? Well, the reason why is they do help stop routing loops, but they can also cause problems. And there may be times


where you have to turn one or two of them off. So, the first loop prevention mechanism that we have is a maximum distance. With RIP, the maximum distance that's defined is 16, I'm gonna grab my pen here, 16 hops. So, once a RIP network is 16 hops away, it is then considered dead. So, if we had a loop


that did happen in router.. Let me put my letters back here C, B and A were passing that network all around the network, that would keep going until they reach 16 hops, and then whichever router got it at the 16 hop level would say, oops, that route is now dead; it's too far away. That also tells


you that RIP can only be used on small networks, because there are some networks that have links that are farther than 16 hops from each other. The second one that you see is route poisoning. Route poisoning kind of integrates with the maximum distance. And what it does


is advertise that the network is down immediately. So it seems kind of funny, but routing protocols built-in themselves do not have a way of saying, this route is down. That's not what they're designed to do. Routing protocols are designed to tell each other what routes are up. So route poisoning


had to be specially engineered to say, Router C, as soon as this network goes down, poison it, kill it. And the way it kills it is by setting it to a maximum hop count. You know it kind of triggers another rule. These, these rules integrate tightly together. So as soon as that network admin trips over the wire,


over here in Arizona, it poisons the route and says, well, this is now 16 hops away, and the next update that goes out will advertise that. So router B gets it and says, oh, well that's the maximum, so that route must be dead. Now, the third one is just logical. One of the reasons


this whole system happened, was router C sent an update two seconds ago, right? And so when this network went down it had to wait 28 more seconds before the next update went out. And with that delay, router B was able to send an update and say, hey, router C, I've got a route to 1.0 and that caused the whole problem. So triggered updates integrates with route poisoning, which integrates


with max distances, which says when that network admin trips over the wire, immediately, immediately negate all timers. All bets are off at that point. You've had a major network change. So at this point, we will trigger an update; overrule that 28 seconds you were going to wait, router C, and as soon as you see the network go down, send a poisoned route, telling router B the network is down.


Split horizon, split horizon is one of the most difficult to remember, but one of the most critical ones, and one of the ones that causes the most problems when, when you are using these loop prevention mechanisms. If there's one that you're going to disable


it's probably split horizon. And when we get to some of the advanced WAN networks I'll bring this back up. What split horizon does is tell routers: Do not send updates back in the same direction you receive them on networks that are being advertised. Let


me explain that in plain English. Let's say that you and I met on the street. And you came up to me and said, "Hi Jeremy, my name is Mike," and I said, "Hi Mike." And, and you said, "Jeremy, I have brown eyes." Now, would I ever tell Mike that he has brown eyes? No, because that would create a people loop. Meaning, if, if Mike and I were to


meet on the street, and Mike said, "I have brown eyes," and told me about that, I would never tell Mike he has brown eyes, for many reasons, but primarily because I don't want to start a people loop because I would say, "Well, yeah, you have brown eyes," and Mike would say, "Yeah, I do," and I would say, "No, you have brown eyes." And we'd just keep going around


and around until both of us, Mike and I, died. So split horizon is a rule that says, do not tell routers about routes they told you about. So when router C says, Hey router B, I know about Router B is now banned from telling router C about that route. Brilliant! Because


that's how this whole thing started in the first place, right? Router C heard about a route that it told router B about, and that's what caused router C to point to router B, and started the whole loop from the beginning. Now, you'll see when we get to some of the advanced WAN network diagrams, why this can cause some problems, especially in networks like frame relay. But for now, split horizon is definitely


a good thing. Last, but not least, is the hold down timer; your best and worst friend when it comes to loop prevention. Hold down timers says, I will not believe any other updates about this route for x amount of time. Here's what I mean: When this network goes down, router C sends a triggered update saying, it's down. Router B receives that and says, well, that's, that's


a big change. Let me immediately tell router A about it, and both of them will set a hold down timer. This is my little clock. Now, that hold down timer can vary depending on what protocol you're using, but what it does is it says, I will not accept any more updates about this for a certain amount of time. The


reason that this is in place, is because of flapping interfaces. If you've never heard of a flapping interface before, what it is, is it's an interface that goes up and down, and up and down and up and down, and up and down; a million times a second. Or maybe


not that many, but a lot. It's just constantly going up and down. It's caused by a bad network cable. It could be a bad connector, you know it's not plugged in quite all the way, but it's in most of the way. Or, it could just be a network interface card, a network card that's going bad. Now, the problem is, is we introduce this system of triggered


updates. Well, if we've got that, that can destroy a network when combined with flapping updates. Because, or flapping interface, because when this goes up immediately router C says, hey, router B, it's up. Router B is like, hey, router A, it's up. Oh, nope, it's down. Down, down. And everybody's


adding and removing that route 1,000 times a second from their routing table. All the routers on your network has their processor utilization shoot through the roof. So, what hold down timers do is say, ok, you told me it's down, I will not believe anything else about that. Now, that's great in the sense that


you've prevented flapping interfaces, but it's bad in the sense that you've got this IT admin, right, who tripped over that cable, and he sees it. He goes, "Oh! I can't believe I did that." And, you know, plugs the cable back in. Well, immediately, router C is going to say, oh, ok, it's back up, but router B is not going to believe that. It's going to say, sorry, you've told me it's down,


and I'm going to believe it's down for x more seconds. I think by default on a CISCO router, it's 180 seconds. 180 seconds! Can you believe that? That's a huge amount of downtime just because someone unplugged a cable and then tried to plug it back in. So, all of those five things


are loop prevention mechanisms, and they are all drawbacks of using the RIP routing protocol. Now, let's change our focus to the link state routing protocols, which have no loops because they have a completely different system of handling routes and route updates. First off, link


state routing protocols form neighbor relationships with each other, rather than just sending broadcast or multipackets, multicast packets to everyone. So, for example, I gave you the example of a distance vector routing protocol being like you walking in front of a group of people into a microphone and saying, hey, everyone, I know about these networks. Well, in


a link state routing protocol, if it was the same situation, you would stand up on the stage and then you'd go, you know what, Let's, let's not do this. Let's walk down. And you would find the first person in that crowd that you would want to exchange route with, routes with and you would say, "Hi, my name is Jeremy. What's


yours?" And they would say, "Hi, my name is, my name is Michael." And you would say, "Well, Michael", it's funny, I'm doing this odd system where I'm saying you, but it's really me. So, how about I flip it to me. I would say, "Hi Michael, I know about these routes," and Michael would say, "Great! Let me put them in my routing table. Jeremy, I know


about these routes." And I'd say, "Great! Let me add those to my routing table." And then, we just look at each other, and I would say, "Hi Michael." And he'd look back and say, "Hi." And then I'd wait, and then I'd say, "Hi Michael." And he would say, "Hi." And


we keep doing that all day long, "hi, hi, hi". That's actually the technical name of a protocol called the hello protocol. OSPF uses this protocol known as hello and it sends it much more frequently than RIP to make sure that the router is still online. Since I am just sending a single message to another


router, I'm just saying "hello", I can send that much more often than RIP could when it was sending broadcasts and multicasts packets because it bothered the whole network. If you were to tune RIP down to send those more often, you would cause some major network problems. So,


OSPF and other link state routing protocols use "hello". After the initial routing tables are exchanged, routers just send small, event-based updates. Meaning, with distance factor, we sent the whole routing table every 30 seconds. With link state routing protocols, I only send an update when I need to send an update.


When something changes, I would say, "Hi Michael, just went down." And you go, "Oh that, that's great! I'll remove that from my table." And then I just look at him and go, "Hi Michael." Nothing more; I don't need to send any more updates, unlike RIP. So there are only two link state routing protocols


that exist today. That is OSPF, that's what we're going to talk about here, and IS-IS, which is covered more in the CCNP curriculum. So, to wrap up this conceptual video on routing protocols, let's look at the advantages and disadvantages of using a link state protocol. Advantage: they are much faster to converge. They can


find problems on the network and repair them much faster than distance vector. And the reason why, is they're saying hello more often so they can detect a failure much, much quicker. There's no routing loops because the routers have a complete road map of the network, which we'll see as we dig deeper into OSPF. So


they don't, they don't ever get confused. They don't ever need loop prevention mechanisms. If you've got a road map, there's no chance that you're going in the wrong direction. Unless you don't know how to read a map. Finally, it forces your, you to design your network correctly.


And I have that as both an advantage and, you can see, a disadvantage that's because link state routing protocols do require a solid network design. Meaning, if you've designed your network poorly and just assigned IP addresses where you wanted to assign them; put a network here, put in a network there. No real design in mind. Well, link state


routing protocols are really not going to be an advantage to you, at that point, because they will cause worse problems on your network than if you had used distance vector. So, some of the disadvantages is: number one, they do consume more resources on your router. They'll use more processor and


more memory utilization because they're simply more complex. They do require a solid network design, and I'm, I'm skating around that one for now, the deep definition of that, because as we look at OSPF specifically, I'll show you what a good design looks like. Finally,


link state routing protocols have technical complexity. There's a lot to them and there's a lot to know about them if you want to use them efficiently in your network. So, there is a lot more education necessary to use link state protocols. We've now taken our first step back into the routing protocol world, since the ICND1 videos. As we've looked at distance vector versus link state. So, let me summarize, we looked at the two


classes or umbrellas of routing protocols. All in all, distance vector, you can think of as easy to configure and featureless. Meaning, they don't have that many features, whereas link state you can think of as complex and require a lot of tuning, but they do have just about every feature you would expect from a routing protocol. So that's the difference. We then looked at the


loop prevention mechanisms of distance vector, which are really a Band-aid for some of the problems introduced with the routing protocol that broadcasts in all directions everything it knows every 30 seconds. Finally, we looked at the advantages and disadvantages, and what the big difference is when using a link state routing protocol. I hope this has been informative for you

Routing Protocols: OSPF Concepts

Routing Protocols: OSPF Configuration and Troubleshooting

Routing Protocols: EIGRP Concepts and Configuration

Access-Lists: The Rules of the ACL

Access-Lists: Configuring ACLs

Access-Lists: Configuring ACLs, Part 2

NAT: Understanding the Three Styles of NAT

NAT: Command-line NAT Configuration

WAN Connections: Concepts of VPN Technology

WAN Connections: Implementing PPP Authentication

WAN Connections: Understanding Frame Relay

WAN Connections: Configuring Frame Relay

IPv6: Understanding Basic Concepts and Addressing

IPv6: Configuring, Routing, and Interoperating

Certification: Some Last Words for Test Takers

Advanced TCP/IP: Working with Binary

Advanced TCP/IP: IP Subnetting, Part 1

Advanced TCP/IP: IP Subnetting, Part 2

Advanced TCP/IP: IP Subnetting, Part 3

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16 hrs 32 videos


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Jeremy Cioara
Nugget trainer since 2003