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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

Routing Protocols: OSPF Concepts

Routing Protocols: OSPF Configuration and Troubleshooting


It is now time to take the concepts we've learned and apply them in OSPF configuration and troubleshooting. We're going to look at, as we walk through here, at the general syntax; that's how we'll start off, we'll look at the diagram, we'll look at the general syntax to set up OSPF and get it running on all our routers.


As we do that, we'll be verifying what we're doing. You can see verification is my final thing but we'll be verifying what we're doing as we go. The 2nd concept I'm going to talk about is the router id or the name of the router. How what what importance that


has and how to set that? Then finally we'll look at the verification and troubleshooting commands with OSPF. So let's get going. Configuring OSPF is not much more difficult than configuring most of the routing protocols but there are a couple of tweeks that I need to show you. First off, here's our network


diagram that we've been using thus far and will continue to use. We've got router 1, router 2 router and router 3. Now, as of right now they're all running RIP and we're going to convert that over to run OSPF. Now if I were to diagram out my areas and this


is going to be a really rough sketch, I would go in here and I would say this: Router 1 encompass all the way down here. Router 2 and what I'm going to do is this is all area 0. Now the first thing I want to mention is that the CCNA exam; if you are a exam prep, the CCNA exam only tests on something known as single area OSPF which in my opinion, ah okay; a lot of people run OSPF in a single area. A lot of small


to medium size networks which is why they they test on it in the CCNA. The CCNA is meant to operate in those environments but to really understand the power that you have with OSPF you gotta see multi area configurations. So forgive me. I'm going to add it in here. We're going to make this area 1. Now it a multi area configuration is so much; well I will say it is is so little more this is horrible english here. There's


not much more to it is what I'm trying to say. You're going to see the single area config. I'm just gonna add one or two more commands and you'll see it convert to a multi area configuration. You can see this, to simulate this environment because we only have three routers here, I'm going to pretend that that router 3 has connections; all these 172.16 networks in area 1. We 're going to break it off and we're going to summarize. It's going to be awesome, I'm telling you.


So that's the script ; so, first thing I'm going to do, is I'm going to hop over to router 1. Let me get my terminal ready ready here. Bring it into view; here we go. I'm sitting on the access server. I'm going to router 1. I'm going to type in show ip protocol just to verify; Yep RIP is still running. Let's kill it. You go in and


type in no router rip which turns off rip on router 1. Hangs there for a moment because it's shutting down the whole process and now we're going to add OSPF. We've got no routing protocols running, so I'm going to type in router OSPF followed by a process ID.


Now this process ID just identifies the process on your router. For example, if you go on Windows and open task manager; let me see if I can open it here. Right here I've got all of these different processes running in in Windows will actually identify them all by a process ID and if you get into in depth you know how task manager operates you're able to kill processes with Windows, same thing with Linux. Well in a router you need to identify what process


ID this OSPF will be identified as. It does not have to be the same on all the routers, I could use 1 on router 1 and 50 on router 2 and 6000 on router 3 but with that in mind most people will make it the same on all your routers because if you make em different you have to remember it on every router you go to. So I like using router OSPF 1. Now once I'm under here, I need to type in my network commands.


Now think back to RIP. The network command does two things. It identifies what networks to advertise for example when I identify and say This network will be advertised this direction, it will say:" I know about 192. 168.1.0/24 and I will advertise that network and the second thing the network command does is say: "Send hello's in this direction".


Now with RIP there is specific ways we had to type in the network statement and samely so with OSPF. OSPF has a very specific way to type it in which is far more flexible than RIP but also keep in mind I've got my internet connection running over here. Do


I wanna advertise that to the rest of the OSPF domain; no, and in the same way do I want to send hello packets out here? no, because that's not secure. I don't want my ISP to form an OSPF neighbor relationship if they want to do so this interface will be exempt from both of those criterias. Now I know some of you might be thinking well you want


the routers in your network to access the internet right? You got the internet right over here so shouldn't you advertise this link to em; well yes, we do want them to access the internet but at the same time advertising this link will not allow that. That will just allow them to access this link. We need to advertise


in a default route meaning all 0's remember that 0 0 0 0 route. We need to advertise that in into the network so everybody has a default route out of the corporate network so, we'll have to remember to do that. First off let's turn it on on router 1 and then jump back to my terminal and I'm gonna type in network followed by what network I want to advertise. In this case, flip back; I'm


doing 192.168.1 so is what I'm going to advertise. Now this is the same so far as RIP right. In RIP we would type in the classfull network we want to advertise. 192.168.1 is a class C network so I type that in but OSPF requires, notice, incomplete command. It requires


that I add on something known as an OSPF wild card mask woww the wild card mask, I love this concept. It is unnecessarily complex for for for no good reason. Everybody that I've taught this to is like why did they do it that way. I don't know just because that's that's what CISCO does and this isn't just a CISCO thing. Just about every router will require wild card


bit so what is a wild card ? What it is is kind of like a match statement. Here is the idea. I'm going to come back over here and if I were to go to router 1 and type in network, where is my pen I have to follow that up with wild card mask and a wild card mask; the simplest way I can define it is exactly the opposite of a subnet mask so, I would go in here and do 0.0.0. 255 what? That's right. Remember our subnet mask is 255. 255.255.0 that's class C. A wild card mask is exactly the opposite. If you want the simple


formula just take and subtract your subnet mask from this and you'll get That's how you figure out a wild card mask. Now I know you're looking at that going I don't need a formula for that but when we get to access lists, you'll thank me for that.


Here's what it means? I know just throwing this out there doesn't mean anything. Anytime you see a zero in your wild card mask, line it up and match to the network that you've typed in so; zero matches here zero matches here, zero matches here. In deeply technical terms that means look at these meaning look for interfaces that begin with 192.1 68.1.0. The 255 means in technical terms I don't care.


What that does is now instruct the router when I type in that wild card mask; look for interfaces on yourself. You've got ethernet 0/0. Look for interfaces that start with 192 is the first one. Look at these 168 is the second one, one as the 3rd octet and then I don't care what comes after that, in this case we have a.1 on the interface but it's saying I've got a.0 but this could be anything from 0 to 255. You could have any IP address on here that starts with 192.168.1 and OSPF will say:"I don't care about this last digit right here. I'm going to run


OSPF on that interface." So this gives me a more flexible way of identifying interfaces. For example, let's let's jump down to router 2 here. If I was on router 2; check it out. I've got 192.168.1 and in one network. 192.168.2 in another network over here and 192.168.10 and 20 as sub interfaces that are routing between my VLANs here. Now if


I were to do this with RIP or with a wild card mask of this, I would have to type in 4 network statements. Network 192.168. is a wild card mask. Network is a wild card mask. So you can see it's kind of an efficient so I could go in there and say:"Well I'm going to type in network any guesses? 255.255. Again what this means is I will run OSPF and advertise any network that starts with 192 look at this 168 look here 255 says I don't care" and "I don't care" so immediately OSPF goes on the router and begins looking at all of the routers interfaces and goes oh; well this one starts 192.168 and I don't care what comes after that. This one over here starts with


192.168 and I don't care what comes ; wow my pen got bigger. I think I clicked something or something. This starts with 192.168 you know, over here I don't care; so it's looking and identifying every interface that starts with that 192.168. That's the power of the wild card mask is it gives us the flexibility of what to type in. I'm going to give you one more


example. Let's say I'm on router 3 and I only; let me see if you can pick up my point here. I only want to run OSPF on specifically this interface. I don't want any other interface in here to run OSPF, no matter if I add interfaces in the future I want to make sure that only that interface will run OSPF.


Are you catching my hint? I'm gonna type in to do that network 192 with my big kindergarten marker here, 168.2.2 with a wild card mask of Ahaa that says: run OSPF on specifically, look at this, look at this, look at this look at that. Every part of that IP address


is specifically identified so it will only run on there. Now I use this wild card mask all the time not only because it gives me complete control of how OSPF operates, meaning I get to identify exactly the interface it's going to run on but also it eliminates a lot of complexity in my own mind of what I need to type in. I mean if you think about, if you want to run OSPF on


a router all you gotta do is go to that router and type in, let me do a do command do and if you haven't seen it do does show commands from any mode. Do show IP interface brief and I say ok those are my 2 interfaces so I'm just gonna identify that, you know, network is my wild card mask. That's what I would type in to start on


just that. If I wanted to run it on my internet link i would type in 68 110.171.98 0000 and that would run it on exactly that interface. So that's that's how the OSPF network command works. Let me clean up all this gibberish there we go, that looks a little better. Now let's get into the configuration.


So I'm gonna go to router 1 and type in network. Well let me just do that show IP interface brief, do and I'll do network and I'll use my short cut and let's see what it's looking for next. Area up and then what area do you want and I can type it in and we've we've already determined area zero is the backbone. It's


always the first area that you configure good, so by typing that in I am now running OSPF on that interface and I'm advertising the network that belongs to that interface out into the rest of the world. Now I want to make sure I emphasise because this this


boggled by mind when I got into CISCO. What you type in here is not what you advertise. You are not advertising 192. 168.1.1. You are advertising the network that belongs to that interface. When I type in show IP interface and look the /24 network belongs to that interface. So that's what you're advertising. So I can type in show IP


protocol now and see I am running OSPF. I'm currently routing for that network which belongs to area 0. My router ID is this that's the name of the router and we'll talk more about that in just a moment and so what first router is done. Now I'm not going to have


any routes because I haven't formed any neighbors. We'll see a command show ip ospf neighbor, which will show your neighbors, none, I have no friends so sad. So router 2 over here says " I need to join this OSPF network", so let's hop down there. Router 2 and I'll do configt no router rip, good bye rip. It is now disabled on router 2. Router OSPF 1. Let me do that do show IP interface brief and there's all my interfaces on there.


Let's use the the wild card mask to our advantage here. I'm gonna do network and remember that says I care about any interface starting with 192.168 that's all of my interfaces on this router. I will add those to area 0. The other area the other part of the ip addresses I don't care about, so all the interfaces on here will begin running OSPF as soon as I type this in.


I hit enter. We're now running OSPF on all those. Let me do a show ip ospf to prove it. I can see that, oop that's not what I want; show ip protocol. Oh check that out. I was trying to get there before our neighbor would form but, good grief I'm just not lucky here.


Show ip protocol. We see I'm running OSPF. I'm routing for all the networks that start with 192.168 my router ID or the name of my routers so when I do a show ip ospf neighbor; now look at that. I have formed a neighbor on OSPF. They are Their IP address is this is the router ID the name of them this is the IP address I use to communicate and this is the interface I go out to speak to them. Look back at our diagram and we


can see sure enough that's router 1. This is us router 2 and we're speaking out fast ethernet 0/0. Now let's hop back up to router 1 and do a show ip ospf neighbor here as well. I can see that I have a neighbor that's their router ID the name of the router, but I'm communicating with them on the IP address Again, I have a whole slide dedicated to the router ID in just a moment but for now I can see I've formed neighbor relationships so when I do a show ip route I expect to see drum roll please, OSPF routes. Check it out there they are: OSPF, OSPF ohh look at that. I have a static route I had that in there


from when we were doing our VLAN labs. Let me do a show run, check this out. I'll show you a cool short cut include lines that have ip route in them because my static routes are IP route so I can go in there. I want to remove my static route I don't need it


any more. OSPF is doing it for me no pasted in there IP route. That's exactly what I had in my running config so I'm removing that. Now when i jump back I expect to see my static route replaced by an OSPF route, good. We don't need statics any more. OSPF is doing the work


for us. So we're now learning all of these routes via OSPF and I have my default route down here going to the internet. Let's just see something. Let's jump down to router 2 and see if it knows about the default route. Do a show ip route. Ah bummer. Look at that, no default route which means no router 2 getting to the internet.


Let me show you how OSPF takes care of that? On router 1 the one with the default route I can go under the OSPF process and type a single command "default-information originate" think about that command. Any default information that you have a.k.q default route, go ahead and originate that


meaning send that into OSPF so, send that to other routers. Now when I go back down to router 2 show ip route; sweet, look at that OSPF route is now shown up on router 2. Router 2 now has an, this is E2 external type to route to the internet through router 1. Now as this is where I lead you into the CCNP. In the CCNP you'll learn the difference


between external type 1 and external type 2 routes and what those are all about but for now router 2 has a default route and should be able to get to the internet once we set up NAT and that's coming. So router 2 is now good to go. Now let's hop on over to router 3 because router 3 is still running RIP. I'll go to 3 no router rip good bye. I'll do router ospf 1 and underneath router 3 let me do a show IP interface brief. I can see that I have my ethernet interface right here, that's connected to the lan. My serial which links back to the wan


and then all these quote unquote simulated networks they're considered loop back networks with all these IP address and that matches the network diagram over here. I'm going to show you first off area 0 getting NAT set up and then I'll add in our multi area so I'm gonna type in network, let's do the same thing here 255 area 0. That will add any interface with 192.168 in front of it to area 0 and you can see I formed a neighbor relationship. I can do a show ip ospf neighbor


and there I see my neighbor. I can type in show ip route and my router is now receiving OSPF routes, even the default route from over at routef 1 so it is able to get out and access the internet. So with that in place and I can tell you that's virtually what you need to know for the CCNA exam.


That's how you set up OSPF in a single area. Let me expound now. Let me have the chains released and I will add in area 1. I'm going to go in and I'm gonna type in network 192 dot, oh wait a sec; 172.30 cause I've got 172., oh no I don't match what I really have these are 172.30 networks. I accidentally put 172.16 over here on the diagram so imagine pretend those all say 192.168 .30 and then I have a 0 1 2 3 4 5 6 7 you wanna see something fancy. I'm going to show this to you because we're going to need it when we get to access lists but how would I create a summary route for those. Well think back to the previous


video when we talked about route summarization. I would go in there let me actually type this, this will be a little cleaner than trying to scribble it in there. Get myself a bigger font. 172.16 and this is 172.30, sorry I mistyped those, 0.0 in binary 172.30 is the same between all of them. The 3rd octet is what I'm concerned with so, let me go in there in binary is all 0's eight 0's and the last one is all zeros but let's just focus on the 3rd. I'll just do first three octets. One is172.30.00000001; Two, 172.30.0000 10 that's 2 in binary; three 172.30. 11 you're getting the idea? So if I already go all the way down to 7 dot dot dot, 7 would be 172.30. 1 2 3 4 this will be 16 8 4 2 1 that is 7 as a binary number. So by grouping all those together I am able to say that 172.30.0 through 7 have the first let's see we've get 8 bits in common 8 bits in common so that 16 17 18 19 20 21. So this is my dividing line. You can see this is where 0 through 7 are all different so I can say that I have 5 bits here so a summary route for 172.30 .0.0 through 172.30 is 7.0 is 16+5 is 21 or if I were writing that summary route in decimal with the subnet mask 255.255./21 would be 248.0. That would be the decimal version of the subnet mask so, that's a summary route that groups all of those up.


Now let me show, now this is; what I'm going to show you is just at this point showing off not not showing myself off but if you were to do this for somebody you'd be showing off but I'm going to demonstrate a skill that is going to give you great success when you to access lists. What wild card mask could


I type on router 3 that would run OSPF on just those interface? We have a subnet mask that says:" this subnet mask matches you know 172.30.0 through 7 or summed up in this. Remember the formula I gave you how do you figure out a wild card mask? You take all 255's and subtract the subnet mask. I'm going to subtract that summary subnet mask


248.0=0.0.7 255-248 is 7.255 255-0 that is a wild card mask. That will run that I can I use to identify to run OSPF on only interfaces starting with 172.30.0 through 7 because this is a summary route that encompasses networks 172.30.0 through 7. Now like I said, this is just showing off because you can accomplish the same thing by going in here and typing with a wild card mask that looks like that and that would work because all these interfaces start with 172.30 and you know that's what we're saying is important here but we can also do .255 and that would say run OSPF on any interface that starts with 172.30 and because of this it's saying it and has 0 through 7 in the 3rd octet. That's how to impress your friends but when we get to access lists that will become an invaluable skill because that will help us be very specific with what we want to deny or allow.


More on that later. For, for now I'll use our bragging wild card mask there and I'll say: "this is in area 1" because looking at our diagram that's where where we are. So when I hit enter I have by typing that one command created an ABR, an area border router that is routing between two separate areas. Now that that that is all there is to


it. There's no I'm an ABR command so, I can go in there and type show ip protocols and I can see that I'm routing for 192.168.00 in area 0 and I'm routing for this network in area 1. Now when I go back to router 2 check it out; I'm going to go to router 2 and do a show ip route.


Ohh that's awesome, awesome look at that. We have OSPF routes in our table, the default route that router is getting from router 1 and remember where router 2 is. Router 2 is right here. It's only going to learn about the default route because it already knows about all this network over here and it's going to learn about this route the 3.1 in its own area and all these are in area 1 and look at this; there is the 3. which is is just a normal OSPF route and all these are area 1 routes a.k.a. Inter Area, see that little ia there. That is identified as an inter area route. Now as I mentioned if you're


just breaking into multiple areas and not doing summarization you're doing no good and this is something I mentioned in the previous video because that's the whole point of breaking into multiple areas is now you can summarize. Now I know I know I'm going


beyond the CCNA here again, let me emphasize CCNA is just a single area but I've got to show you this one final command. I'm gonna go ohhh, holy cow; there's Vista for you. I'm going to go to a the router 3 and I'm going to type in router ospf 1 and I'm going to do area 1 range and then what I want my summary route to be. Now we already figured it


out right here in our binary our summary route for area 1 to encompass all 7 of those networks will be or with this subnet mask behind it that's a good summary route to encompass, just those 7 networks. So I'm gonna jump back over here, and do area 1 range followed by a normal subnet mask no wild card mask 255.255 .248.0 done. I have now encompassed and I've told router 3 which is an ABR the range for area 1 is with this subnet mask which emphasizes 0 through 7. Now let's let's check this out. I'm gonna go back to router 2 and do a show ip let's check this out. I'm gonna go back to router 2 and do a show ip route. Look at that. Isn't that ohh, I'm telling you, you'll get this excited


when you get into OSPF. We've got this which it is shows /21. It even did the the mask for us. It said you typed in that subnet mask which is also a /21 there and you can see right there is subnet and we have 1 inter area route that is available to us, a summary route. Notice all 7 of those previous routes that we previously were looking at in that routing table have disappeared and been replaced by one summary route. Now watch this, watch


this. Hang on, ah am I going too far. I'm going too far but I've got to do this one more thing. I'm going to create one more network. You see my loop back interfaces right here 172.30. 0 through 7. I'm going to create one more. I'm going to do interface loop back 8. This is how you can simulate networks by the way and I'm gonna do ip address I'm gonna add another network that's not part of the summary mask because if I go down here; 8 in binary I'm running out of room man, I'm gonna say 8 is 0 0 0 0 1 0 0 0 that's that's 8 in binary which does not have the first 5 bits in common which goes outside of our summary mask and when I add that in their, ohh wait a second.


I used the custom wild card mask to add that to OSPF didn't I. We'll have to do something; ignore what I'm typing right here. Just ignore it you're not you're not seeing what i'm typing. Did you see that I didn't see that and I'm going to type in network with that as my wild card mask. So I've added that network to OSPF because with


our custom wild card mask before we just added 0 through 7 that manually added 8 in there. Now, if I go back to router 2 show ip route. Look at that it's separate. The summary doesn't encompass it because the summary only includes 1 through 7 so, what what we've proved by doing this is that our custom summary mask is working perfectly encompassing just the networks that we wanted to. So yes we did go beyond the CCNA but that


is multi area OSPF that is a big part of the CCNP. Woo, I've got to breath here. OSPF is exciting. I'm telling you it is a very cool protocol. Our last few concepts we'll talk about in this video is number 1: understanding the router ID and then number 2: we'll just look at how to trouble shoot OSPF which is really focused around one thing. So the OSPF router ID


is the name of the router. We've seen it a couple times when we were going in. If I'm on, let's shoot over to router 3 and do a show ip ospf neighbor. Router 3 sees router 2 as the router id or neighbor id but it communicates to router 2, its neighbor on the address If we look back at our network diagram, where did that go, diagram, that's that's right you can see right router 3 communicates to router 2 on So why is router 2 identified as that when we're looking at router ID. You can see


.20.1 that's it's router ID. That's because of this rule. The OSPF router ID identifies the router to neighbors. It's the name of the router. It is by default the highest physical interface at startup. So if you've got this router sitting right here and you start the OSPF process and router OSPF 1 and you go in there, the router id will be this guy; the highest physical interface beats this and beats that because it is the higher interface. Now loop back interfaces also beat physical so


if I go in there and add a loop back interface of an extremely low IP address; since it's a loop back it automatically wins. Now if I add another loop back of we'll say this one now wins because it's the highest loop back and there is a new command router-id the new router ID command beats all. So let me show you what what this looks


like. I'm going into router 2; we're on router 3 why not stay there. I'm going to go and do router ospf 1 and I can hard code in there and a lot of people will do this router-id enter. Now that is the new name of the router and it says in order for this to


take effect you have to reboot the OSPF process, so I'll add in here clear OSPF processes. It says are you sure; yes not something you want to do during production time but this will take down the neighbor. You can see that the neighbor is gone from full to down and then reload it and it went back in and it's now full again, neighbor reformed.


So I go over to router 2 and do a show ip ospf neighbor and now I can see, see that, that's the name of router 3 that it sees and communicates with router 3 using the IP address Now, at this level we're only mentioning the router ID as I just say that's the name of the router but as you get into the CCNP world you'll see that the router ID has a lot more ramifications.


There are commands that you type in that require you to know the name of the remote router the router ID so, at this point that's just what the router ID is. Finally as we move into trouble shooting OSPF this slide should look somewhat familiar to you. This is the same slide


we looked at in the previous video when we talked about how routers form neighbor relationships. 90% of your troubleshooting on OSPF is focused around routes not showing up because neighbors aren't forming so the best thing that you can do as you troubleshoot is to do that show ip ospf neighbors command.


Do you see a neighbor there? Chances are if you are not seeing routes you're not seeing a neighbor so you're going to go through and mainly look at these criteria. Do the hello and dead timers match between me and my neighbor. Are we using the same subnet


mask on the interfaces that we use to communicate? For instance, is this one a /24 and maybe this one a /25. Neighbors won't form. Are we in the same area? Has this one been defined in area 1 and this one definined in area 0. That would be a conflict. Neighbors. Wait a second


that's not right. Neighbors this this shouldn't have a star forgive me if you jotted that down on a peice of paper it is it is not, that should not have a star. I can't believe I did that. Neighbors is a list of what neighbors each one of these knows about. It


will say:" I know about these as my neighbors and I know about these as my neighbors", that's how the routers know and they send hello's back and forth if they're already neighbors or not if they see each other listed as a neighbor that does not have to match forgive me.


Priority DR/BDR. Those are CCNP concepts but the password. If you are password protecting your OSPF network so routers can't just come in and join the routing fun without providing a password, it will say does the password match between these two routers? If not the neighbor relationships will not form so again, just going through and checking these 4 criteria hello and dead timers, the network mask, area id and password that will tell you whether or not these neighbor relationships are forming.


If you want to trouble shoot this process even further the best way to do; let me get my thing moved in here is to do a debug ip ospf and its adjaceny; adj. That will show you the neighbor relationships forming. When I clear my process clear ip ospf process you actually see on the screen it shows neighbors going down and shows neighbors coming back up. It's a lot of info but this


is a complete neighbor forming process between that was the second neighbor coming up and in everything it goes through as it forms a neighbor relationship. If there is a problem if there's an area in this match or a subnet mask it will be in this output that just scrolled up on my screen. It will say:"oh neighbors are not going


to be forming because you know the area ID does not match area match conflict or because my authentication password fails so doing this one debug, will show the full neighbor process for me. Just walking through that simple configuration of OSPF I feel like there's this this can of OSPF concepts that I just want to open and just say let's talk about everything but, then this video would be 5 hours long and we would have a lot of stuff that does not relate directly to the CCNA. As you can


hopefully get an idea of just by seeing this there is so much more that you can do with OSPF but that should give you enough at the CCNA level to set it up, to do basic route summarization that's even beyond the CCNA and understand; here's the key, you should be able to understand any OSPF config that you come across in the real world just by doing a show run and seeing what commands that have been typed in.


To wrap up I want to hit the high points. We looked at the general syntax to configure OSPF. The major difference is that wild card mask with the network command. We then saw modifying the router ID, which is the highest physical interface by default, the highest loop back interface if you have one of those on your router and it can also be modified by typing router-id from router config mode and whatever you want your router ID to be.


Finally, we looked at the verification and troubleshooting. Verification we did throughout the configuration looking at the routing table, looking at the neighbors and trouble shooting we did by looking at the debug command, debug OSPF adjacency, verifying that the hello parameters do match between two neighbors.

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