Architecture

33. CEF & Adjacency Table

Next topic: We have traditional MLS multi-layer switching and setting. Using Cisco Express forwarding So what's the fundamental here? The key concept here is route one and switch many. And again, if you correlate this with the SDWAN, you have the control plane and data plane. The control plane will take all the decisions and the data plane will forward the packet. Correct. So here also, you'll find that you have a control plane called a route processor or RP. And then you have the data plane. That is the switching engine. That is, the Se routeprocessor will take the decision and then it will programme the switching engine. Now I have taken the decision. This is the source; this is their destination; you need to forward the package. This is the way that the forwarding will be very fast, and this is the way that the multi-layer switches or switches provide the line read speed. Correct. What is Cisco Express Forwarding and how does it work? What are the key components we have? Again, the core of Cisco Express forwardingis to take the decision once and then everyone will follow that decision. So route once means you have the brain, and the brain is the supervisor engine in the chassis type of architecture. So either we are using the catalyst,six K or 4K or 4500 switches. We have the supervisor agents who will take the decision and then they will programme the line card to forward the packet. If you have the fixed type of switchover, So, for example, 385-03750 etc., safety can be enabled in the hardware. Okay, safe is the feature. Here you can see in the diagram and understand more, that this will provide you with the fastforwarding of the packets because all the time the request is not going to the CPU. The CPU will take the decision once. So you are pointing the packet to the CPU, which is building the routing table and the app table. But they will programme the switching engine, or they will programme the line card where you have the dynamic engine called Fib. And then you have the next hop admins, or you have IP to next hop mapping from where the packet will move to the destination. Correct. So here in the diagram clearly you can see that the different rules of all these components, the routing table, are built. That's the route process processor. And then you have the ARP table. That's L three, two L two mappings that will resolve the Mac address. Now you have the dynamic entry. That's a table-forward information base. And that fit table will be arranged in such a way that you have the longest prefix match to the lowest prefix match. That's the beauty of this table. And then finally, this, whatever information they've taken from the art table. So now you have IP to the next top mapping or you know who your next top agency is, and you can forward the packet according to the layer forwarding engine. Actually, this is the mechanism that MLS is using. So now you have different types of terms. You have a routing information base that will form forwarding information based on the longest prefix match. So that is the LPM and then you have the ARP tablet. The hat will do the l three-two-l two mapping and then you have the agency table that will be used by the fifth. So I have put all these points here. If you want to read these slides, you can read them, but whatever. We are discussing the same thing here also. Once you have your rib Once you have your app table, Once you have your Fib Once you have your agency table, If you want to verify it. You can go and verify it like Ipsaf if you want to check PsaF entries in detail. You have that detail option so you can come to know who the network you are looking for if you want to check that particular network. So we have options that we can explore and check the particular destination network. So for example, through ipsep prefix IP, and then if you want to check the longer prefix matches, because this entry or the safe entry. They will be in a manner that they will have the longest match and then the least match, obviously. If you have the longest match, then only the fifth entry will be the natural choice for the fibentry. You have to check the next job for the longest match. correct? Alright, so in this way, Fibonacci will come into the picture, and when you check the Fivinter, you will see that you have multiple next stops attached or attachedor in the same network in the other network again. It depends on who exactly is your next stop. According to that, they will be the cable, and again, if you want to see this in detail, you can go and check through IPSE, the network and details, where you will go and get the detailed information about the agency, about the next job, dependencies, etc. But okay, now the next important thing we have is the agency table. So we know at this point of time that you have the fixed components, for example, the rip table, and then you have the ARP table. Now you have the dynamic entry as per the longest match, that is the flip table, and then you have the agency table. Now this agency table obviously will be taken from the ARP table. So ARP is doing l to l two mapping, and then when fibre is looking for their next stop entry, they contact the addressing agency table, and then they can get the next one based on the longest match. So that's the thing we have that's important in the agency table, but there is other stuff as well inside the agency table. If you want to check that you have this option, You can go and check that you have the summary and detail option as well. The agency table will look like this. So first you can see that the first few numbers belong to a TOMAC address and then the rest of the keywords are there. But what is important here in the agency table is to understand the different types of keywords. So, while you are checking your agency table, you will find that you have null agency. What exactly does "null agency" mean? Is that used to switch back to the time for null interfaces? The null interface is always defined by a router or switch. It represents a logical interface that silently observes packets without actually forwarding them. So you may have NULL interfaces. They are not actively forwarding the packet from one place to other places, but they are silently absorbing the packet. Then you have the drop agency. Obviously, the drop agency has named suggests that they are going to drop the package and the reason may be encapsulation failure, unresolved values, unsupported protocols, no valid routepresents, no valid agency, you have checked some errors, etc. For now, if you want to go and check this drop agency, you have this option. You can go and type "show safe drop" and then you can check encapsulation failure, no route, etc. Okay, then the third one is discard agency. Discard agency means your next stop is discarded by some blocking rule, ACL rule, et cetera. Then finally, you have the point agency. Point agency means that you don't have your adjacent table,you don't have your next stop and you are forwarding the packet towards the CPU or towards the process. If you want, you can go and check shows nosafe switched because they are not safe switches rather than their CPU or the RP switched or RP processed. So according to that, you can go and check these important keywords. So here you can see that you have an allergen key. You have brought urgency, you have discarded and pointed out urgency. Finally, when everything has happened and the package is ready to go, the package will be rewritten in the egress or when it is leaving the switch on the router. So what are the things they will change? They will change the layer two destination. Obviously, the layer two destination will be the next Mac address. They will go and change the layer to the source address. That will be the Egress Macaddress of that particular interface. They will go and check the TTL, which means they will go and decrement the TTL by one. They will go and check the layer three IP checksum. They will go and check layer two checksums as well. So these are the things that the switch will check before actually sending the packet to the egress. Finally, safety will be enabled. Nowadays, it is enabled on all the routers and all the switches. But suppose you want to disableSafe on a certain platform, you have options. You can go and type "no IP Safe" on some platforms. We have to write no IP without cash or maybe both. Okay? So in this way, we can disable the shift. So obviously, everything will be handled by the CPU or by the routing process. In this case, and this is not the recommended way, but sometimes, for the sake of troubleshooting or other reasons, we used to do this. Alright, so let's just stop here.

34. TCAM

This is the last session in section one. We are going to verify the SIF and we'll see the TCAM as well. Let us begin or discuss safe verification. So, first and foremost, you can go to and run the command show IP interfaceVLAN and show IP interface and the interface name. Suppose it is a VLAN interface, you can go and give the VLAN and the number. Here you will see that "safe" is enabled. So that means this particular interface is enabled, although you have other important information as well with this command. So this is a very simple and easy to run command and you'll get a lot of information related to that particular interface. To understand the safe or to verify the safe isenable or not to run the safe command, we have to show IP safe command if we run that command. In the next shop column, you can see that you have received the attached and other information. So what does it mean? The first one here, you can see that you have 32. This is nothing. But suppose if you don't have the agency table, if you don't have next up, then the packet will be pointed to the CPU or the route process. That's the first entry you have. Suppose you have 192-168-1990 24 andattached as your next stop. That means that this is your interface. That's why it shows attached. And again, you can see that you have one nine 900:32. That's the network. This network and this network are received So that means, obviously, your network. But the thing here is that this is a reserve entry. Here you can see a more detailed explanation. So if it is zero slash 24, and if it is attached, it means it is a connected interface. If it's 32, that means it is reserved for the exact network or network address. And this is used to contain agency packages sent to a network address. If the network is not directly connected, In this case, there is no agency and the entry is marked as a receipt. So I think you understand that at 00:32, this is for the network. Then you have one last entry, and this is also a reserved entry. This is very much like the host route 32 host route. So you have a network route or you have a network, and you have host route reserve entries. Then again, you have two means that you may have to do two as your neighbour switches. So you are connected with your neighbour switch, whose IP is dot two. After that, you have two 5532. That is nothing but the broadcast address. That is also marked as a receiver, and this is also a reserve entry. If you want to know more details about safety, you can go and check through IP safety and then the details will get the detailed explanation. Finally, we have to understand the TCAM resources. So here you can see that you have forwarding resources. Inside that, you have Mac host routeIGMP route, LPM route, and multicast route SCP. Now, this particular output on this particular reference belongs to the 9300 Catalyst, which is the 9300 Catalyst,which you have an output like this. Then you can see in the TCAM resources that you have security Ackle, Kos, and Apple service Ackle. Inside that you have PBS, Netflix, Span, Max Act, and you even have the entries for Netflix as well. Now, here you can see the exact partition. So for forwarding resources, we have a 32K reserve. The host route is 24K IgM, eight K, longest prefix match,eight K, multicast route, eight K, z, eight K. And then again, you can see and have a reference for the increased feature resources for TCM as well. At the bottom you have the Netflix entries for 64 Ksik as well, if you want to see this in detail. So you can go and run this command tactics, nine K, show platform hardware, fedfeed, switch, active, forward ASIC resource. And here you can see that unicast addresses,max value used value igmpl, two directly or indirectly connected states, and all that information are in this particular output. So if you run this output, if you want to see the details of this from the CLI, you can execute this command and get it. Finally, just for reference, you have the default STM template network interface. You can see the forwarding resources, the TCAM resources, and the reserve entries. All right, so let's stop here.

Virtualization

1. Virtualization

In our enterprise core curriculum. Section two belongs to virtualization, and the percentage is 10% weighted. Here you can see the topics. The topics are related to a little bit of VMware type of thing. You have to learn to understand hypervisor typepoint type two virtual machines and virtual switching. I'm going to record small videos and I'll go a little bit beyond what they are. Slavery is just to our knowledge and security purposes. So you'll find it very informative. All 14 videos will cover not only the Cisco side of hypervisor, virtual machine, and virtual switching, but also the VMware side. So I'm going to touch on both. Then we have two more where we have to learn about Vrfgre and Ipsick. Then, two or three, we have Lisp and VXLAN. Now for Lisp and VXLAN, I'm going to upload the same video that we have done for Section One for Lisp and VXLAN. So there is one video for Lisp and one video for VXLAN. So here are two, three, A and B. You'll find some sort of reputation in terms of just sections two, three A and B, which we have already done inside section one. This particular section will find that it will go over very quickly and you'll also find it very informative and it will build up your skill set and knowledge base.

2. What is Server

Then what is the server and operating system? What's the basic definition of "server"?A server means that someone who is hosting services or someone who is providing services, but you can see that server. They have various components and these services take requests from the client. They process those requests and provide certain services. Now the server consists of the CPU, internal storage, main memory, interface, and card. This means there is various input and output processing. There are various components inside the server. After processing those servers, they provide the services. Right now, the main component, or to be very precise, the main software component we have on the server is nothing but the operating system. Now the operating system is someone who is the brain, and you can see the definition of the operating system. An operating system can be defined as software that controls computer resources and provides common services for other computer programmes that run on top of them. So, for example, on my laptop I have the Windows operating system, and once I have the Windows operating system, then I have different different applications. So, for example, I'm using Gmail, I'm using web browsing, I'm watching YouTube, I'm uploading courses to Udemy, watching courses from different different vendors, uploading courses here and there, doing some chat, playing games,all those applications that are hosted and that are actually connected with the operating system. So in the operating system, you can think of Asa as the boss, who is providing the timeslots and providing the instructions. So you can think that the operating system in the core and a small programme are connected somehow with this main program, this operating system programme, and then the operating system has their own mechanism to provide time slot, to provide space, to provide competition,everything that is provided by the operating system. So you can think this is the hurt inside the server which is responsible for all the other main vendors: Microsoft, Linux, Freebst,Apple, Android, Cisco, iOS, Chrome, etc etc.Some of the operating systems here can see the difference that they are used on a laptop or server et cetera. But some of the operating systems are used inside the networking devices, like routers, switches, firewalls, et cetera. correct? Now here you can see the view of the operating system. You have the kernel space, that is low-level programming, and that is the programming that is associated with the operating system. And then maybe I have user space and variousapplications like email, chatting, online, video games, etcetera. Etcetera. Etcetera. And these applications, which are programs, these kernelprogramming, which are the programmes with which they are associated, and these hardware that you are seeing, for example, Ram, Nick, disc, all have their own programs. So, actually, behind the scenes All the programs, from high-level language to low-level language, they use to consult each other with different types of messaging. bus. In between them, they are providing the output as requested as an input, so we are giving some input processing. That is the programme's message bus. They are sending and receiving the instruction, and then they are providing the output. That's the basic of the operating system The following section will explain how this hypervisor operating system works and how it can help us reduce overall costs, or more efficiently use different types of hardware. components or resources with the help of emulated features that we have inside the hypervisor program.

3. What is Virtualization

What is virtualization, and what will we achieve with it? In the final section, we will look at servers and the definitions of server and operating system. You think virtualization is a type of emulation where you have fixed hardware, on top of that you can use some emulated programs, and then you can install various operating systems. So what is the traditional way to install an operating system? Say I have my laptop. I can go to my laptop in that laptop. That is my fixed hardware. In that laptop I have a fixed CPU, memory, Ram, et cetera. So I have my laptop and on top of my laptop I can install an operating system. So, for example, I'm using the Windows operating system. Now think like this: you have the hardware. So I have the hardware on top of that. So let me write the hardware. On top of that, I can install some sort of emulated software. So I can install emulated software. This is actually termed a "hypervisor." So I can install a hypervisor on top of hardware and now whatever you say, for example, RAM, CPU, network interface card memory, etc. So you have that fixed hardware they can use and they can think that I have my own RAM, CPU, network card memory, et cetera. I can install operating system one,operating system two, and operating system three. Obviously, there should be some limit to how many operating systems you can install. I'll write this on top of the fixed hardware and the hypervisor. If we use emulation or an emulated method to install the operating system, this is referred to as a host. So on top of the host, in this course we are going to study the VMware hypervisor, which is nothing but ESXi. So on top of that, I'm installing various guest operating systems. So these are nothing but guest operating systems. In this way, we can save an enormous amount of hardware resources, and that's actually something termed "server virtualization." Now there is a difference between server virtualization and hardware virtualization, and you will understand this thing coming forward or going forward. So, for example, when you use all of the hardware resources perfectly, that is nothing but server virtualization. And suppose you know the term, for example, unified computing system inside Cisco, so you have a unified computing system inside that you can install so many servers with server profiles, etcetera. That is one example of server virtualization. The other example we have seen just now is that you have one big hardware resource and then you install some sort of hypervisor emulated software on that and then you install the guest operating system. So that is an example of server virtualization. When we are talking about network virtualization, now it is everywhere. So this network virtualization is used, for example, in the SDN solution. For example, my Sdvan is a type of network virtualization, or inside that I have network virtualization. Network virtualization is used by Cisco application-centric infrastructure, VMware, and NSX technologies, for example. Can I give you a simple example? Yes, the easiest one is the VR of virtual route forwarding. This is again a type of network virtualization. So, the virtualization technique entails Here you can see this is an example of server virtualization. Suppose you have one hardware and one operating system. We are not using any type of virtualization. But you can use it in between the hypervisor and the virtualization software that is known as a host. On top of that, you can have any number of operating systems. Here you can see the different operating systems we are installing and then, on top of that, we are installing the applications. So in this way, we can reduce the cost and it is actually quite efficient. Almost all the companies are using it that way. This method only works here because you can see that you have multiple ESXi. So you may have one host, two hosts, three hosts, with a few of the hosts having a few of the operating systems or guest operating systems, and a few of the hosts having a few of the guest operating systems. And suppose you want to manage the entire infrastructure. Later on, we'll see how to manage the hypervisors cluster of hosts, data center, et cetera. So we have one VMware, popular tool or popular software or suite of software protocol, whatever, and you have a management layer that is accessible via the VR server and vs your client. In our lab, we will also use the Vsphere client to manage. So here you can see that you have the server and here you have the client. With the help of one web browser and one application, you can manage the entire big infrastructure. So now you can see the complexity has been reduced, the overall virtualization of hardware has been enhanced and, in this way, companies can save a lot of money. So what is the hypervisor? A hypervisor is defined as software that can emulate hardware such as a CPU, memory, RAM, storage, and so on. for the installation of a guest operating system. In the context of server technology, a hypervisor is a software programme that allows the creation of virtual servers. So whatever we have discussed is the same thing. Again, if you want to see this diagram, you can see that you have your server, your hardware, and you put in your operating system and the application. But in this way, you're not using the virtual way of using the resource, the hardware resource efficiently. Instead of that, what you can do is have your hardware put the host or the hypervisor and, on top of that, you put the operating system and application. So easily can you improve performance, cut costs, make better use of hardware resources, have a single management plane for different guest operating systems or applications, and so on. Again, we have one more diagram here. You can see that you have one big framework. You have fixed hardware, the 86 architecture. You can have your virtualized software here. And on top of that, virtualised software, you're installing an operating system application. operating system application,operating system application. Now, all these CPU, RAM, NIC, cards, discs, whatever you're seeing here in the diagram, actually those are termed "asa virtual Ram", "virtual memory," "virtual Nic," etc. So you have your real CPU, memory, and NIC disk. Furthermore, you are treating everything as a virtual, virtual, virtual. And that's the power of the hypervisor we have in this course. Basically, we are going to focus on VMware ESXi. But there are so many good vendors. There are vendors like VMware ESXi, theHypervisor, and Microsoft HyperV. These are the popular vendors. Then we have the Linux KVM. These three are the topmost trending hypervisors. Apart from that, we have the Red Hat cTrix zen server. This is also very popular. Citrix server We have Akel VM. Then we'll see later on that we have two types of icebergs as well. Then you have Microsoft Windows, Virtual PC,Oracle VM, VirtualBox Palladium, and Software Mac. You have these many vendors who are providing this hypervisor software. So I hope you understand what a hypervisor is, why we use them, and how we can go about managing them.

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