Pass Cisco DCCOR 350-601 Exam in First Attempt Easily

Introduction

1. 350-601 DCCOR introduction

Hello everyone and welcome to the DC Core Course. The full name is "implementing and operating Cisco Data Center core technology." Now let's check what are the breakup, what are the things that we have to learn in this course? You can see that it is divided into five different sections. Section one network, then compute, storage, automation and security. Now, the interesting thing here is that if we go and add automation plus security, the complete ratio will be 30%. And now we know that demand for automation and security is booming; it's on the rise. So it's highly recommended that you focus on automation and security as well in the coming future. But apart from that, we have network, compute, and storage. For many years, these have been the mainstays of data centers. So what type of networking thing? As Cisco engineers, we are familiar with networking protocols such as routing protocols and switching protocols. And in data centers, we have some other things as well. Now, since the evolution of ACI, let's see software defined, network, waste of networking. Still, there are so many things to learn inside the network, because now, with the help of ACI, you can manage your IT infrastructure, at least inside the data center. Correct? Again, nowadays we have different types of integrations, meaning you can integrate with ACI, Cisco, or other STM solutions like DNA, Stan, et cetera. Maybe you can do some third-party integration with respect to services or security appliances. Correct. So thing is this that the network evolution, the computer storage, everything is evolving actually. And now, if we go back ten years, we can see that you have those things: you have a network, you have computers, but they are very widely distributed now. Things are collapsing and integrating inside one big, giant box. That's the future we have. But yes, we have to learn about the network, compute, storage, automation, and security. Again, if you drill down inside the network topics and the compute topics storage, we'll go deeper into this in upcoming sessions. So for example, we can see that inside the network we have to learn about routing protocols. And basically the good thing about this course is that it assumes that you have some sort of theoretical background, which means, you know, we have one other course, CCNP Enterprise. So, you know, the CCNP Enterprise certification indicates that you have a basic understanding of OSP, PGP, P, M, and even ACI. So in this section, you will go and learn the implementation. But what I have done is that I'm going to cover the theory as well, and then you will see the practical lapse as well in this particular course. So I hope that you will learn new things in this particular course. And you can apply this knowledge in your professional career in your data centre work profile as well.

2. 1 1 a OSPFv2, OSPFv3 Introduction

In one. One we have to learn about OSPF v two and v three, version two and version three. OSPF Two belongs to IPV four type of networking and Ospfree belongs to IPV six type of networking. So first of all, we are going to learn about OSPF version two. And what are the things we have inside this. You can see that there's only one section in this, that for AOSP version two and version three, we have to learn how we can go and run this command or how we can go and configure this and check the output. But what I have done here is that I will start with OSP of the basics, then OSP of the LSA type, Dr. BDR, a different type of network, virtual networking, et cetera. And then we'll go inside the OSP of verse three. Because they are nearly identical in terms of functionality. They are using the same type of algorithm or mechanism. Either it's v two or v three. The difference here is this that in v two is dealing with IPV four and v three. It is dealing with IPV6, complete IP, IP addressing schema change within v4 and v6, and we are aware of that. So now what I have done here that you have complete nine videos after this related to OSPF V two, where you will go and learn all these concepts and then subsequent what I will do that inside OSP vthree I will cover in two videos so you will understand both v two and v three. Once you complete this, then we'll go and move to the UK BGP his, then we'll also go and watch the upcoming nine videos related to verse two.

3. OSPF Basics

Let's start with OSPF. Now OSPF, which is the open source path-first protocol, is a link-state protocol like ISIS. Instead of sending the entire topology table hop by hop, the link is protocol sends the state of a link to the neighbour device. Now, how does this technology work, and let me try to draw it here, so generally all the link state protocol they form first the neighbour table so they can send the update to all the adjacent devices or neighbours with the help of the neighbour table they form the topology table sometimes we refer to this as an entire database as well and finally they ran the SPF algorithm here from the topology table they are going to form the best path That is the routing table so we have three different types of types of table neighbour table or database table. topology table, and then finally the routing table.

Now, the mechanism behind this and the theory behind this will be seen in upcoming slides, so OSPF is entirely dependent upon areas Generally, we are saying that we have one backbone area, so here you can see that you have area zero, and logically all the areas are connected with area zero. Now, these areas are 32 bits. They can be a flat number or defined as in dotted representation zero zero, as this area has continued area, as you can see you have area zero and then area one. Two. three, so maybe you can think that you can't connect area three with areas five or four? Yes, we can make that connection, but as you can see, area four is not directly connected with area zero, so somehow I have to create a tunnel, or in the case of area three, I have to create area three as a tunnel, or we have to use some sort of virtual link.

So area four can think that it is directly connected to area zero, so we need to make such an arrangement, and then the link state advertisement will flow from one place to another, which is the LSA. correct the LSA sent by OSPF when there is a change to one of its links and will only send the changes in the update LSA are also refreshed every 30 minutes. How we can summarise it is that OSPF is a linkage rate protocol dependent upon the area where they are sending their LLCs or their advertisements to all their neighbors, and with that, they are forming the neighbour table. topology table, and finally the routing table Apart from the fact that OSPF traffic is multicast, they are using 2240 for all the routers and 2240 for the designated router The theory behind this we can discuss in an upcoming session. They are using the Dijkstra algorithm to build the routing table from the topology table, and they are supporting the variable length subnet mask, so here you can see that first of all they form the neighbour table. Then they form the database, then they do their algorithm. That's the SPF algorithm that extracts the SPF algorithm. Finally, they will form the best table; that is, the routing table. OSPF supports IP routing. Their ad value is one-tenth their cost; their metric is cost. They are going to form the neighbouring "tabletto," call the table, and route the table. All the areas should be supposed to be connected with the backbone that's the area zero. If you have non backbone area connected with any other area, then you have to create tunnel or what's your link in between that. Now suppose we have such a type of topology here. We can see that I have area zero connected with areas one and two. So now what we are going to tell you about these devices, these routers, is that they are termed border routers because they are on the border of different going to te and we'll see how the routes are reflected as a result of that. So when we are talking about the routes, you'll find that you have O routes and then OIA, which is OSPF. So you have two types of route, OSPF, intraare route, that is this. Then there's the interior throughout the space, which is this. And we'll see that we have a one and a two-route coming from the outside as well. Now, if you see this diagram, it's actually a very simple, straightforward bet that we have two or three routers in the area. But suppose you have 50 or 100 routers in the area, and suppose I have 200 routers, all of which are inside area zero.

So at that time, what will happen? Because of the competition, running the SPF algorithm becomes CPU intensive. rather than if you have a small area and then you have 50 devices, 100 devices, and 50 devices in those areas. So in that case, all the areas will run their independent SPF algorithm, and then they will send the update to the backbone. So in that case, the way that we are going to run the SPF algorithm, or in other words, the process, the CPU utilization, the memory, will be optimised and will be used better. Because now you're running the SPF algorithm across small areas, and then those areas are going to send their LSS to the core or to the other areas. Correct? So that's the thing; that's why we don't have a single logical area but rather several. And then we are going to divide the devices, or the routers, inside the area. Then you can see that if you have a device that is not connected to area zero, you must create the virtual link, which is the device that separates the area. They are termed "AVR." Then you have an internal router, then you have a backbone router. Again, these are just terminologies. All right, now here you can see that you may have a chance that you are connected with a non-OSPF protocol. So you are getting the route example from the EIGRP domain. So in that case, that router istermed asbr autonomous System border router.

As you can see, Cand. D. is an ABR area border router. However, router G is Asbr because the route is now coming from the other routing domain to OSPF. Okay? So here you can see that if you have any other routing domain, that will be treated as a separate autonomous system, and then you have to do the redistribution. Obviously, the router G will do the redistribution from EIGRP to OSPF when it is coming to OSPF and from OSPF to EIGRP when you are sending your update to the EIGRP domain. We now have Even and E types of areas in that case. Now, what are E one and E two? As you can see, by default, it will be OSPFexternal area type 2, or E 2. So include only the external cost to the destination network. External cost is the metric being advertised from outside the OSPA domain. This is the default type. Then you have E, which will also have the material; that is the cost. But this will be added, which means it will add to the cost per hop per router. So include both the external cost and the internal cost. That's why you have the external cost plus the internal cost to reach the ASPI to determine the total metric. But E 2 has only external costs that will be constant. So in summary, here you can see that you have internal routers, that allrouter interfaces belong to only one area. You have ABR, you have ASVR, and you have a Backbone router that is inside area zero. Okay, so this is the baseline summary for the OSP routing protocol. In the upcoming sessions, we'll learn more about OSPF terminologies, and we'll have to perform the lab as well.

4. OSPF LSA Types

So what type of LSS do we have in OSPF? OSPF has a long list of LSS We are going to discuss the top five, at least, because we are going to use them more and more. So we have LSA. You can see type one and type two. Now this type one and type two LSAs are reside within the area. They are very much area-specific specific LSA. Then we have types three and four generated by the ABR area border router. They can flow from one area to another, as we'll see in the upcoming slide. Then there's Type I policy, which means non-OSPF protocol and is generated by an autonomous system border router. They are going to generate that. Now you can see a detailed explanation of each LSA. Type one is LSA, and type two is as well. They are within the area of use of type 1 LSA in that they have the link, obviously, the status, and the cost of all those links, which are generated by all the routers in a network. So you can think that type one has a default LSA generated by all the routers within that area. Then there are type 2 LSAs produced by Dr in the OSPF network or domain. Again, this is unique to the area where we have a broadcast network. Obviously, at that time, Dr. VDR will come into the picture. Then we have the network summary LSA. That is type three. What it is doing that generated by Apr and this can be used for inter area communication. You'll see that all the places you have this interior link So you have areas connected by different areas, and all these AB are shown in the diagram. They are going to generate type 3 LSA to do this inter-area communication. Then we have ASP or something. Now the next question here is suppose from OSPF interarea you have to reach to non OSPF domain. So for that reason, we have an autonomous system border router summary.

LSA means somehow you need to reach, or somehow we have a route to reach, the non-OSP protocol. Then we have external LSA type five. Now this is generated by the ASR, and this information will flood all the areas. So all the areas have obviously undergone redistribution. All the areas should know how to reach the autonomous system border router or the network behind the ASPR. We have type six as well. That is the multicast ASP of type seven as well. That is not a stubby area, and this type of injury is actually very important, and we'll discuss this later on. in the diagram. You can see that you have area one, area zero, and area two. So you have this router that belongs to area one, area two, and area zero, and the network LSA is type one, and type two LSA will be generated in that. Then you can see that routers C and D are ABR.

So they are going to generate type three and type four. And then G belongs to us, so he's going to generate type 5, let's say. Okay, great. Then how is this OSPF going to form the OSPF neighbour relationship? So if you go and connect to OSPF with two routers in between, suppose, for sake of simplicity, I have only two routers connected in a network. So in that case, what will happen? Suppose I have router one and router two, and these two routers are connected, or they are inside area zero. So obviously these routers are within the area, and suppose if it is a point-to-point network, then they will send and receive the router, let's say. So what will happen is that they are going to send the packet in the point-to-point network or in the broadcast network; the hello timer is 10 seconds, and that timer is 40 seconds. So it's one into four. And on the broadcast network—actually, on the NBA network—that will be 30 seconds. And then the date timer will be 13 to 4, which is 120 seconds. So they will send and receive hello packets, exchange them, and if they match certain criteria while sending and receiving hello packets, they will form a neighbour relationship.

So here you can see: what are the things inside the hello packet? What are the fields inside the Hello packet? They contain area ID, area type, prefix, subnet mask, hello interval, dead interleave network type, and authentication. Basically, it is said that they have eight fields inside the hello packet, and you should match at least the area ID, the subnetmask, hello and dead interval authentication, et cetera. So some fields are mandatory and should match between two routers to form the neighbour relationship. Okay? So here you can see that a labour table is constructed from the Ospflo package, which includes the following The router ID, the current state, directly connected interfaces, and the IP address of the remote interface of each neighbour will be seen in the last section. And we'll go and we'll learn the command "show IP," OSPF neighbor," and then we can see the specifics about the neighbors. Now, the next topic here is the OSPF-designated router and the backup-designed router. So, what is going on, and how will the Dr BDR be formed, or how will the Dr BIDs be selected? Let's discuss that. So here you can see in the diagram that, first of all, these devices should have their priorities. So let me show you what I try to tell here. I should have let that slide. So you can see that these devices have their own unique identification. That's the router ID of all the routers in the network. They have the router ID. We can configure it manually. Assume a device has the loopback interface or physical interfaces. First of all, they will check the loopback interface if you are not doing it manually. So that loopback interface will become the router ID, or the highest physical interface will become the router ID. So they should have the router ID that will be set by default if you're not doing it manually. Once they have the router ID, they will perform the Dr VDR selection, which will only occur in the broadcast network. As shown in the diagram, if router ABCD is connected to the shared network or the broadcast network, they will go and select the Dr and BDR. Now what will be the selection criteria here? The criteria are determined by the router's priority, which is configured per interface basis.

The router with the highest priority becomes the Drand, the second highest will become the BDR, and the rest are Dr dwellers, something like Dr BDR others. Okay? If there is a tie in priority, the router with the highest router ID will become Dr. Now we can go ahead and set this priority like this. Also we can go to the interface and we can set IPOs PF priority and then we can force to make certain devices as a Dr or BDR. Now by default, the priority will be one. So obviously the selection will happen with respect to router ID. So whoever has the highest router ID in the network will become D-R-B-E like that. In that manner, suppose you don't want certain routers or devices to be included in the BDR selection. So you can go to the interface and set the priority to zero.

So if you set the priority to 0, that device will not take part in the Dr. video. Okay, so what are the important things we have studied in this video? With that type of LSA, then how are they going to form the OSPF neighbour relationship? What are the important fields you have inside the hello packet? All the devices are sending hello packets to the peer devices or neighbour devices to form the neighbour relationship. Then how they are going to form the J-bar selection? Again, the router ID will be an important factor here. And as for the router ID, they are going to form the drvdr because, by default, we are not setting the priority. The priority will be set to 1, and we will enter who is the Dr and who is the BDR into the router ID.

5. OSPF DR BDR & Lab

Let us learn more about OSPF neighbour state, and then I'm going to perform a small lap task where we'll learn more about the OSPF process, how OSPF actually neighbors, and even the baseline commands of OSPF as well. So now, when the OSPF is formed, the first stage is that they have to form a neighbour relationship. When they are forming the neighbor relationship at that time, they are exchanging, going through a process, or going through multiple steps. So what are those states we have here? You can see that they will begin with the down in two ways, and so on. So the down state indicates that no hello has been exchanged, but the actual process will start from the init state. In each state, the devices will start sending their hello packets. We know that inside the hello packet we have some important fields; a few of them are mandatory, like the area, the authentication, the network subnet, et cetera So few of the fields are mandatory that two sites or the neighbours should match those mandatory things, then they will go to the two-way state. If the devices are in the broadcast network, they must select the DRM and the BDR by the end of the two-way state, and the devices are forming the neighbour relationship by the end of the two-way state. Okay, then we have the external start and the external exchange. Externally, start and exchange are simple, with devices selecting who is the master and who is the slave in order to exchange databases. So obviously the devices are sending their link state, or LS information, to each other to build the database. Once they have the database as per the master and slave entry, as per the master and slave role, they have to exchange their LS type, correct? So someone may send a link estate advertisement, someone may ask for a link state request, and things are going in depth when we are talking about the exchange state. Then we have loading, where all the devices have to sync their databases, and by the end of this loading state, the OSPF process is forming the topology table. Remember, we have three important tables. We have a neighbour table, so by the end of the two-way state, they will form the neighbour table. By the end of loading, the devices will form the topology table, and finally, once they have the topology table on top of that, the devices will run the SPF algorithm. The shortest path is found first by the algorithm, and then they have to form the routing table. We'll see that if we have the broadcast network, then they will have rules like BDR and DRL.

So, if we have these roles in a broadcast network and they are others, they will go and stop at the level of two-way because what is happening in that situation is that you are giving Dr. and BDR the authority to exchange all the LSS with all the driver rather than all the others. They are exchanging their database package, so that means they will be stuck at the two-way state, and all the Dr. others will be struck at the two-way state. They will not have the full authority to exchange the databases. All right, so we have a small laptop topology in this first lab just to start with what we are going to do—that is, we will go and initiate the OSPF process. So let me show you that although we have this master lab topology, what we can do as per our requirements is go and use it.

So what does it mean that we'll go and make these devices? For example, R R-2 and switch 10-1 are within area zero at the moment, so they will be part of area zero, as will this switch that you are seeing here. I'll make Switch 105 as a switch; later on, we'll make this sleep, but for now, I'm assuming I have R 1. R two and switch 101, and the IP that I'm going to use. The IP will be—let me write here the IPS—and according to that, I'm going to configure the lab. So the IPS that I want to use is, for example, ten one one two" as for the names of the devices, and here is an example. They are inside the same broadcast network, so you can see that they will go and form the Dr. and BDR loopback addresses I'll give the device a name like 11222, and this will be 10 110-110-1101. We are going to initiate the OSPF process inside area zero, and then we'll see how they're going to exchange all those hello packets and the important LS type.

All right, so let me go and log into the lab devices. All right I logged in, and we know that we have other interfaces and links connected that I don't want. So this is the topology that we have. What I can do here is start with 10 one. Let’s get the last two out of the way first. Let's take a look at this, and I want to shut down a few of the interfaces that I don't want to use, so for example, I want to use the www only interface, so I can do one thing with the interface range E 0223 shutdown because I only want to use the last two interfaces, so the rest of the interfaces I'm making shutdown like that, and I also want to make shutdown if I go and check CJP neighbor, so I have that I want to use now Switch two isn't needed in this lapse, so we'll leave it, and then I'll go to switch number five, and we should double-check the last two configurations. So I will go ahead and check one last time and see what is configured Nothing is configured if nothing is configured. dat this point of time at least what we can do is we can make this interface as a switch port.

Okay, so here you can see the capabilities that I don't want. I'll make this a switch port. Then we'll go back to the switch number five here, as you can see, and the interfaces we have are apart from that. What I want is to make other interfaces shutdown, and we have so many interfaces here, as you can see, that we can leave it there as well, just to check the configuration for any of the interfaces that are connected with router number one. Router two. So these are the interfaces connected. I don't want to do anything. Rather, I'll do one thing that connects range zero to, say, four, maybe, and three. I'll make this as a switchboard, with no shutdown, and then interface E-10 slower zero, which is connected to switch one, which is what interface we have here. Let me scroll up ten slash so I can go here interface I'll also make this a switch port. No shutdown. All right, so we are very much good with switch number one and switch number two. I can go back to interface one and two and make this a switch. Okay, so let me quickly go over what I needed. So one plus two should not be a switched port; it should be a routed port. So I'll disable the switch port and then assign the IP address. So for example, 1021 So what I have done here is to check and show the IP interface in brief. So I have three interfaces: the last two, the loopback interface, and the one where I have assigned the IP addresses. Okay, all right, great. So now we can go to R1 and R2, and the interfaces you can see here So I will go to R one first and I can go to interface e zero. I'll assign IP 10-1, and then I can do a ping just to check that the switch for the end switch is reachable or not. So it is reachable. Then I'll go and create one loopback, say zero, and an IP address. I'll give one to each person in that loop back.

We'll go and check the "show IP interface" brief so you can see that we have the IP configured here. Let's go to we have interface zero. I can go ahead and give the IP like this, and then I'll create one loop back zero where I can give the IP related to as per the diagram or as per our schema, and then let me first try to ping within the same network obviously everything is inside the same network for this example, so what I'm doing is paying to all the devices from R 2, and now we have the baseline IP address connectivity connected. The thing here is that we are going to enable OSPF for all these devices, and we are assuming that all these devices are inside area zero, right? So let's do this.

Let me go back to the lab before doing that. On at least one of the devices, I want to enable the debugging, so I want to enable the debugging of OSPF packets and events, the debugging of IP USPF packets, and then I want to enable the events as well. Okay, let's do this OSPF configuration so we can go to router OSPF, and then you have to define the process ID, say "one" I'm giving at this point in time, then I should go and advertise the network, so network is "I have two networks," one is "ten," and I can go and give the "wildlife bit" inside area zero. This is the format in which we can enable OSPF, and you can see that we have an event because we have enabled debug, and you can see that this router is using this multicast address and the routerID is being selected as one of one, as we discussed earlier if I go and check Show IPOs PF. You can see the rate router ID is one, and we have the other information as well. Okay, so we have the OSPF configuration and periodically he's sending the hello packet.

We can go and check the configuration for what we have done. So we have enabled the OSPF process and then we have advertised the network, correct? So likewise, I can go ahead and initiate the OSPF process here as well, and then I can go and assign the router ID via the CLI command as well as manually as well, but if you do not do this automatically, they will take the highest loopback address as a router ID. So I have network tango and network 222200 area, and let me see what configuration I have done here. Now they try to exchange this neighbour relationship; from there they will go and form the topology table, and finally they will go and form the routing table as well. Okay. So let me quickly see that what I have here is the network because we have used the last 32. That's why I've given you now somewhere you'll find that you're moving to the fullest state, and here if we can see that information in the log messages, so we've enabled the debug and OSPF authentication is zero, we haven't put any authentication, so it's telling you that OSPF authentication is zero, and here you can see that we have this loading to full message.

If you go and check Show IPOs PF Neighbor, then you can see that you have already made the VDR selection already happened .For router one to say that router two is BDR If you go to router two and check Show IP OSPF Neighbor, you will see who the Dr. is. So this 1111 is the Dr. for router two. What is the interface and what is the IP address that we have discussed earlier? Now I'm going to switch number one, and I'm going to do this router as well. And then I will put the network example's back address, which is 1011-011-0100. And then I'll put the network that we want to form the OSPF relationship on. So we have a network and a wildcard bit. All right, and for the time being, within area zero, I will check show IPOs PF neighbor, and you can see that he is seeing who is the Dr and who is the PDR correct the third device. If you go ahead and check neighbor's OSP, you will notice that Dr. other. So now this IP is Dr. We haven't always manually assigned the router ID, but you can see that they can detect it here. It means that the router process can begin assigning the router's IP address or router ID. For these devices, we can go and check like this, and you can see the ID. Now if you want to filter and use what I tried to do with this command, you can simply go and check the ID, which will tell you who the author ID is. All right, so this is the way that they are going to form the DR and BDR. And if I have one more device in the other room, then you could find that the process will stick in two ways. So, if I'm here and I have another device connected to this guy here that is also working as a real, these two devices will stack as a two-base rate, they will not extend the entire topology, and so on. All right, so let's stop here.

6. OSPF Network Types Metric Passive interface Theory

In this section, I'm going to cover OSPF, network type metrics, and passive interfaces. And the lab will be completed in the following section. Now, if you go and check the slippers, let me quickly show you this level. In this level you'll find that in three two, you have to learn about OSPF and you have to compare with EIGRP. So, to that end, I'm going to cover EIGRP in a series of videos. So, once we understand OSPF and EIGR, we can easily compare them. Then, in three dots, two Bs, you can see that we have to learn and understand more about OSPF. And that's what we are doing at this point in time. So let's quickly understand the network type OSPFmetric and the usefulness of a passive interface. Now, OSPF is supporting a wide variety of network type. You can see here that OSPF supports this many network types. Now how do you memories this, because as you can see, it's a big number for this network type? So you can think like this: you have point-to-point and point-to-point, and then you have point-to-multipoint broadcast and no broadcast.

As you might expect, there are two types of networks: broadcast and no broadcast. And then again if we add "point to point" and "point to multipoint." So, point to point—obviously, we know that point to point is just a network of points. Two devices are connecting with each other. It's a point-to-point network. Then what about point to multipoint? So here you can see point-to-multipoint to multipoint non broadcast. So you can consider point-to-multipoint broadcast and no broadcast, okay? So that means you have one, then two, and three. Apart from that, you have network-type type broadcast. So there are two types of networks: broadcast and non-broadcast. That means you have to use five different types of network support. Again, if you check the broadcast and non-broadcast natures, if it is a broadcast, the Dr BDR selection will occur and the neighbor will form automatically. means you don't have to write the manual command to form the neighbour relationship. Correct? But if it is a non-broadcast, and suppose it is forming, you can see that the hello is a unicast multi-less when you are seeing unicast, which means you have to go and use the neighbour command.

So you have to manually form the neighbor, correct? So once we know about the broadcast and non-broadcast, and you can see the timer again, we can proceed. Isn't it 10 and 40 seconds for the broadcast network and 31 and 0 seconds for the non-broadcast network? Now, the same concept can be used here. So you can see that the point is to multipoint. You can think of this as a point-to-multipoint broadcast. So that's why it's a multicast hello. They will not form Dr. Media because, once again, it is point to point and there are so many points to point to multiply. You can think like that. So, if you have a point-to-point network, you will not form the Drvdr because the Dr VDR can be formed with only two devices. Then I get non-broadcast point-to-multipoint. Now this is non-broadcast, so that's why you have to go and use the neighbour command to form the USPF neighbour relationship. That's the whole summary we have for the U.S.P. of network type. So let me go back to the theory. You can see that it's abroadcast now, so it'll do Dr. VDR selection. Then, because this is a broadcast, it is using these multicast addresses, and they will not form the neighbour ship manually; instead, they will form point to point automatically. There's no need to define the neighbors because you have only two ends. They will form a neighbourly relationship. Their time is will be ten and 40 seconds. They are going to use multicast, but also point to multipoint as well.

Everything that is valid here for point-to-point will be valid for point-to-multipoint as well. Okay, then we have no broadcast. Whenever we are talking about non-broadcast relationships, you have to go and form the neighbor relationship manually. OSPF will elect DR and BDR, but neighbor relationships will be manual, and that's why we have this summary. This summary is easy to memorize; there's no need to recall, but this will make a point that's okay. There are point-to-multipoint networks, point-to-multipoint non-broadcast points to multiple broadcast networks, and broadcast and non-broadcast networks. How we are going to do the configuration?

The configuration part is actually very easy. Only one command is there to define the network; you have to go to the interface. Suppose, over this serial interface, you go to the interface and use this command IP OSPFNetwork assumes that if you type question mark, you'll get all of the options. So is it a broadcast? Is it a non broadcast? It's a 2.02 multi-point, etc. For each of these options, you will get And if it is using the unicast method, meaning it is not broadcast, then you have to go and define the neighbor. Otherwise, the rest of the configurations are standard OSPF configurations. So for example, NBM is non-broadcast multi-access, so here we are going and defining the network type as a.2 multipoint, and if it is a non-broadcast, then you have to go and define the neighbor. So just refer to this summary and things will become easier. Now OSPF is using cost as a metric. Here, you can see the speed and the cost. So for example, for fast Ethernet, your cost will be one, and then you can see the photo ethernet token ring for MEPs and the cost. Now, lower is better. So if the lowest cost is there, That will be the preferred path in the route selection. how we are going to do the basic OSPF configuration, although we have done one lab.

So there you have seen that you can go and initiate the OSP process; you can define the router ID; otherwise, it will take the highest loop back or highest physical interface. If it is not configured, then you can define the area and that's it. So this is the baseline configuration. Now the interesting thing is that we are defining the wildcard bit, and now it is recommended that if you know the exact subnets according to that, you can use the exact wild card as well. So, if I'm using point-to-point networks, I can use, for example, 173-21610, which is 10 in this case, and then I can use wildcard. So like that, we can go and use the wildcard wisely. What will happen if you go and initiate the OSP process, and once we start advertising the network or once you put this network command in, they will send the hello packet and the neighbour relationship will start working? We know that steps down in it are two-way excess start exchange loading to full. First they will form the neighbour table and the topology table, and finally they will run the SPF algorithm and we'll get the final OSPF routing table correct. Now the final thing here in this recording as far as the theory of passive interface—the concept of passive interface— Assume that if you do not want to form an OSPF relationship, you can make any of these interfaces passive.

So, if I make this interface passive, we can see that the command prevents updates from being sent to or received from this interface. In this example, it is showing this interface. So if you go and make this particular interface a passive, or any interface a passive, they will not participate in OSPF. Because they have a neighbour relationship, they will not send or receive updates, which is why passive interface is useful. But, in general, we'll do this; no passive interface is zero here, as you can see. First and foremost, we'll make all the interfaces passive. So the first command is the passive interface default. Suppose if you have ten interfaces, that means on all ten interfaces you're not sending and receiving the updates, and then you will go and add the interfaces one by one where you want to send or receive the updates. We have one important note here: The passive interface command will prevent OSPF and EIGRP from forming neighbour relationships out of that interface. No routing updates are passed in either direction. So this passive interface is true not only for OSP but also for EIGRP as well. So we are going to stop here, and in the next action I will show you a few of the things that we have studied here, like network type and how you can go and change the network type and enable the passive interface.

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