Welcome to Jeremy’s IT Lab. This is a free, complete course for the CCNA. If you like these videos, please subscribe to follow along with the series. Also, please like and leave a comment, and share the video to help spread this free series of videos. Thanks for your help. Also, remember to sign up via the link in the description to get all of the lab files for this course, so you can try it out yourself in packet tracer. If you want more labs like these, I highly recommend picking up Boson’s NetSim for the CCNA, click the link in the video description to check it out. It’s a network simulator like packet tracer, but it’s even better, and it includes all of these guided labs to not only help you get hands-on practice configuring and troubleshooting, but also deepen your understanding of the exam topics. I used it myself when studying for my certifications, so I feel confident about recommending it to all of you. If you want to get your own copy of NetSim, please follow the link in the video description. In this lab we’ll do some basic OSPF configurations in this small network. This is very similar to Day 25’s lab, EIGRP configuration, with a few small differences. Let’s get started. First of all, before recording this video I already completed step 1. I want you to get some extra practice with the basics like configuring host names and IP addresses, but at this point in the course I don’t think there’s any need to record myself doing it. So, first up I’ll do steps 2 and 3 on each router. Step 2 is to configure a loopback interface on each router. As I have explained before, a loopback interface is a virtual interface in the router, it’s not a physical interface. I’ll give a brief overview of them in one of these OSPF videos, but basically they are useful in that they can always be in an up/up state, unlike physical interfaces which can go down due to hardware failures, etc. Then step 3 is to do some basic OSPF configurations on each router. I’ll start on R4 and then work toward R1. First enter privileged exec mode with ENABLE. Then CONF T. Let’s configure that loopback interface. INTERFACE L0. Notice these messages indicating that the interface has come up as soon as I create the interface. IP ADDRESS 4.4.4.4 255.255.255.255. Let me check that it was created. DO SHOW IP INTERFACE BRIEF. There it is, and the IP address is 4.4.4.4. By the way, if you really want to make sure the subnet mask is correctly configured you need to use a different command, because as you can see the subnet mask is not displayed in the output of SHOW IP INTERFACE BRIEF. So let’s use this command instead. DO SHOW INTERFACE L0. Look here, ‘Internet address is 4.4.4.4/32’. I like using SHOW IP INTERFACE BRIEF for a quick look at interfaces, but sometimes you might have to use other commands. Okay, now let’s configure OSPF. ROUTER OSPF, and I’ll use a process ID of 4. Remember what I said in the lecture video, this process ID is only significant to the local router, the other routers don’t care about it. Just to show that, I’ll use a different process ID on each router, and you will see that they still become OSPF neighbors. Next up let’s activate OSPF on R4’s interfaces. I think I showed you this trick in the EIGRP lab, but if you want to activate OSPF on all interfaces at once you can do this. NETWORK 0.0.0.0 255.255.255.255 AREA 0. That’s configuring a range of 0.0.0.0/0, which includes all IPv4 addresses. Remember that the network command uses a wildcard mask, so 255.255.255.255 is like a subnet mask of 0.0.0.0. So, OSPF is enabled on all interfaces. In real networks it’s recommended that you be more precise about which interfaces you activate OSPF on, I just wanted to show you that little trick for quickly setting up OSPF in labs. Now, we are also instructed to configure passive interfaces where appropriate. F1/0 and F2/0 are connected to routers, so we shouldn’t make them passive, but G0/0 should be passive. PASSIVE-INTERFACE G0/0. Not only G0/0, but Loopback0 also. Routers will send OSPF hello messages on loopback interfaces, even though they are connected to nothing. So, PASSIVE-INTERFACE L0. I’ll take a look at some OSPF show commands when we get to R1, but for now let me quickly go through the configurations on R3 and R2. R3 next. ENABLE. CONF T. INTERFACE L0. IP ADDRESS 3.3.3.3 255.255.255.255. Now let’s configure OSPF. ROUTER OSPF, and this time a process ID of 3. Let’s try another way of enabling OSPF on each interface, specifying the exact IP address with a /32 mask. First up, F1/0. NETWORK 10.0.13.2 0.0.0.0 AREA 0. Next, F2/0. NETWORK 10.0.34.1 0.0.0.0 AREA 0. Finally, Loopback0. NETWORK 3.3.3.3 0.0.0.0 AREA 0. Here on R3 there’s only one interface we need to make a passive interface, Loopback0. PASSIVE-INTERFACE L0. Okay that’s all for R3, next up I’ll configure R2. ENABLE. CONF T. INTERFACE L0. IP ADDRESS 2.2.2.2 255.255.255.255. Now let’s configure OSPF. Again, I’ll use a different process ID, but usually I’d just use process ID 1 for all routers. ROUTER OSPF 2. I’ll enable OSPF on both physical interfaces first like this. NETWORK 10.0.0.0 0.0.255.255 area 0. Then the loopback interface. NETWORK 2.2.2.2 0.0.0.0 AREA 0. And let’s make that a passive interface. PASSIVE-INTERFACE L0. Okay, that’s all here on R2. Finally let’s move to R1. ENABLE. CONF T. INTERFACE L0. IP ADDRESS 1.1.1.1 255.255.255.255. Now let’s configure OSPF. ROUTER OSPF 1. So, we are told we don’t need to enable OSPF on the Internet link. Why is that? Well, we are going to advertise a default route to the other routers later, but there’s no need for them to know about this point-to-point connection between R1 and ISPR1. If R2 needs to reach a server over the Internet, for example, it just needs to know to send the traffic to R1, there’s no need to know what subnet is used for the connection between R1 and ISPR1. So, we won’t activate OSPF on the interface unnecessarily. I’ll do each interface one by one. NETWORK 10.0.12.0 0.0.0.3 AREA 0. NETWORK 10.0.13.0 0.0.0.3 AREA 0. NETWORK 1.1.1.1 0.0.0.0 AREA 0. Notice that for each router I configured the network statements a little differently. On R4 I used a single command to enable OSPF on all interfaces. On R3 I specified the exact address on each interface. On R2 I enabled the two physical interfaces with one command. Here on R1 I configured the network address of each interface. Just be aware that there is more than one way to enable OSPF on each interface. Okay, now let’s make Loopback0 a passive interface. PASSIVE-INTERFACE L0. Before checking out some show commands here, let’s do step 4 and configure R1 to advertise a default route. First I’ll do DEFAULT-INFORMATION ORIGINATE. Currently, a default route isn’t configured though, so let’s EXIT, and now configure it. IP ROUTE 0.0.0.0 0.0.0.0, and set the next hop to ISPR1’s G0/0/0 interface, 203.0.113.2. Okay, we’re done with the configurations so I’ll use EXIT to return to privileged exec mode. First let’s check out SHOW IP PROTOCOLS. We’ve already covered the output of this command, I just want to highlight that the loopback interface’s IP address of 1.1.1.1 became the router ID, and because we configured DEFAULT-INFORMATION ORIGINATE, it says ‘It is an autonomous system boundary router’, an ASBR. An ASBR advertises outside networks into the OSPF domain, such as when R1 advertises a default route to the Internet into the OSPF domain. Now let’s look at a few OSPF-specific commands. I will cover these in detail in the next few videos, but here’s just a preview of them. First, to view the Link State Database, LSDB, use this command. SHOW IP OSPF DATABASE. Here you can see all of the LSAs in the LSDB. Notice there are a few types displayed. ‘Router’ link states, ‘Net’ link states, and ‘Type-5 AS External’ link states. I’ll talk more about these in the next video. Here’s another command, to view R1’s OSPF neighbors. SHOW IP OSPF NEIGHBOR. As expected, R2 and R3 are listed as OSPF neighbors. And one more command, SHOW IP OSPF INTERFACE. You can specify an individual interface if you want, or just view all interfaces. This gives details about the current OSPF settings on the interface, such as the various timers OSPF uses. Feel free to look around at the output of these commands if you want, but I will explain their output in a future video, just wanted to make you aware of them. Finally, let’s do step 5. Check the routing tables of R2, R3, and R4. What default routes were added? Let’s check R2 first. DO SHOW IP ROUTE. The default route is down here, via 10.0.12.1, which is R1, as expected. Now let’s check R3. DO SHOW IP ROUTE. Okay, R3’s default route is via R1, 10.0.13.1. Now let’s check R4, and you might see something a little unexpected. What do you think the next hop of the default route will be, R2 or R3? Note that the connection between R1 and R2 is a gigabitethernet connection, while the others are fastethernet. Since I already taught you that OSPF uses interface bandwidth to calculate the metric, you probably expect the path via R2 to be preferred, and expect that it will be the only one entered into the routing table because of a lower metric value. Let’s see. DO SHOW IP ROUTE. Well, it looks like both routes have been added, so R4 will load-balance over both paths. Why is that? Well, I will explain that in future videos. But if you want to do some independent research, try to find the answer yourself! If you think you know the answer, post it in the comment section! Okay, so in this lab we did some basic OSPF configurations in this network, including passive interfaces and advertising a default route. That’s all for this lab. Now let’s check out a bonus lab in Boson NetSim for CCNA. Okay, for today's Boson NetSim lab preview we're going to take a quick look at this lab here, planning and configuring single-area OSPF. Here is the lab topology, there are four routers. Routers 1 and 3, and 2 and 4 are connected with fastethernet. But routers 1 and 2, and 3 and 4 are connected with a serial connection, and as it says here it is using 'frame relay' as the Layer 2 encapsulation. So, frame relay is a layer 2 encapsulation, like Ethernet, but it's used on serial connections. Now, some other options for serial connections are PPP and HDLC. Now, in the current CCNA you don't have to know these in-depth. I will mention them briefly in these OSPF videos, but the main focus is the Ethernet layer 2 encapsulation. Okay, down here are the commands you need to know to complete this lab, the IP addresses on each device, and then the lab tasks. So, this lab is divided into four main tasks. Verify initial configurations, plan for OSPF, configure OSPF, and verify OSPF. So, in the first OSPF video, the first lecture video, I only covered the absolute basics of OSPF. So we're not actually ready to complete this whole lab. But that's okay, we'll just do task 1 and a little bit of task 2 so you can see what this lab is like. And if you want to try it out yourself, you can get a copy of NetSim from the link in the description and try it out yourself here in NetSim. Okay, task 1. Verify initial configurations. Step 1, verify the IP address and state of each interface on each router. So, I'm already in the CLI of Router1, so let's check here. SHOW IP INTERFACE BRIEF. Let's check with the IP addresses table here. Serial0, 10.1.0.1, looks good, FastEthernet0/1 (*1/0), 10.0.0.1, looks good. Okay, and they are both up and up. Now let's check out Router2. To open Router2, click here on the right side under devices, and click on console. Okay, serial0/0, 10.1.0.2, looks good. And fastethernet1/0, 10.2.0.2. Okay, and they are both up and up. Next I'll check out Router3. Okay, serial0 is 10.3.0.3, that's correct. Fastethernet1/0, 10.0.0.3, and that is correct. Okay, and finally I'll check on Router4. Okay, 10.3.0.4 is good, 10.2.0.4, that is good also. Okay, so all of the IP address configurations look good, and the interfaces are all up/up. Okay, next step 2, I'll try some pings. So first from Router1, I'll try to ping these two interfaces, this one on Router3 and this one on Router2. Okay, so I'll go back to Router1. Ping first Router2's serial0/0 interface, 10.1.0.2. Okay, looks good. And next, Router3's fastethernet1/0 interface, 10.0.0.3. Okay, no problem. And then step 3, from Router4 ping Router2's FastEthernet1/0 interface and Router3's serial0/0 interface. So I'll ping these two interfaces here. Okay, I'll go on to R4 again. PING 10.2.0.2, that is Router2's fastethernet1/0. Okay. And Router3's Serial0/0. Okay, all looks good. So the initial configurations are fine. All the interfaces are up/up and there is connectivity, they can all ping each other. Next, task 2, plan for OSPF. All four routers should be members of the backbone area. What is the area ID of the backbone? So, as I said in the last video, the backbone area is area 0. Now, for single area OSPF you don't actually have to use area 0, the backbone, you can use any area number, area 1 2 3 4 5, whatever number you want. However generally it's recommended that you use area 0 for single area OSPF. And that is one of the requirements of this lab. Okay step 2, your configuration should be specific enough so that as additional networks are added to the router those networks are not automatically advertised. Okay, so we have to be specific with our NETWORK statements. We can't use the trick I showed you earlier, NETWORK 0.0.0.0 255.255.255.255, to activate OSPF on all interfaces. We should be specific about which networks we want to advertise. Okay, the IP routing tables on each router should be populated with the specific IP subnets in your network. Using the IP addresses table, list the specific networks and masks that should be configured to satisfy this requirement. So, we should configure the specific subnet on each interface. So, all of them are /24, as you can see. So if you want to know the network address just change this last number to 0. So, for example on Router1 there is 10.0.0.0/24 and 10.1.0.0/24. Router2 has 10.1.0.0/24 and 10.2.0.0/24. Router3 has 10.0.0.0/24 and 10.3.0.0/24. And finally Router4 has 10.2.0.0/24 and 10.3.0.0/24. So those are all the subnets. Okay, so that's step 2. Step 3, list the OSPF network commands necessary to accomplish the configuration requirement in the previous step. Okay, so we'll configure the NETWORK statements I just said, but you have to make sure to use a wildcard mask, so the /24 would not be 255.255.255.0, it would be the inverse, so 0.0.0.255. So, just to show you the commands that you would use on each router, let's look at the lab solutions down here. And here they are. So, for example on Router1, NETWORK 10.0.0.0 0.0.0.255 AREA 0, and then the same for 10.1.0.0. And you can check on Router2, 3 and 4 as well. Okay, now from step 4 it talks about some aspects of OSPF that we haven't covered yet in the last video, for example DR, that stands for Designated Router, which is an important topic in OSPF and I will cover it over the next couple videos. So, I'm going to end this lab preview here. If you want to try this lab and all of these other OSPF labs out yourself, make sure to get a copy of NetSim from the link in the description. Before finishing today’s video I want to thank my JCNP-level channel members. Thank you to Florian, Daming, Venkatesh, Kone, Joshua, Jhilmar, Samil, Ed, Value, Magrathea, Justin, John, funnydart, Scott, Hassan, Gerrard, Tibi, Joyce, Marek, Velvijaykum, C Mohd, Johan, Mark, Miguel, Yousif, Sidi, Boson Software, Charlesetta, Devin, Lito, Mike, Yonatan, and Vance. Sorry if I pronounced your name incorrectly, but thank you so much for your support. One of you is still displaying as Channel failed to load, if this is you please let me know and I’ll see if YouTube can fix it. This is the list of JCNP-level members at the time of recording by the way, August 4th 2020, if you signed up recently and your name isn’t on here don’t worry, you’ll be in future videos. Thank you for watching. 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