Module 9 - Cisco Networking Lecture Transcript PDF

make a quiz with this lecture transcript: welcome back in this lecture, we will be looking at the address resolution with respect to IPv four and IPv six. This is the module nine of the Cisco NetAcad introduction to networks lecture series. If you would like to watch the previous lectures, I will l...

make a quiz with this lecture transcript: welcome back in this lecture, we will be looking at the address resolution with respect to IPv four and IPv six. This is the module nine of the Cisco NetAcad introduction to networks lecture series. If you would like to watch the previous lectures, I will leave a link in the description with the lecture playlist, so that you can go ahead and watch them. In this lecture, we will explain how AP and nd enable communication on a network. We will look at the Mac and IP ARP with respect to the IPv four, for example, and the Neighbor Discovery or nd with respect to IB, IPv six, Mac and IP there are two primary addresses assigned to a device on an Ethernet LAN, the layer two physical address, which is the MAC address, and the layer three logical address, which is the IP address, the layer two MAC address used for network interface card to network interface card communications on the same Ethernet network, while the layer three logical address, which is the IP Address, is used to send packet from the source device to a destination device. The layer two addresses are used to deliver frames from one network to another network. That\'s a very important concept that you learn on our previous modules. And if the destination IP address is on the same network, the destination MAC address will be that of the destination device. So this particular slide basically showing that what we already learned, and it\'s just quickly describing what it is. It\'s just a quick summary of what we have covered in our previous modules. Again, if you would like to watch the previous module lectures, you can go ahead and check my YouTube channel, and you\'ll get to those lectures and you can watch them, so you should already have an idea about the difference between a MAC address and IP address. So remember, MAC addresses are used for communication between network to interface card to network interface card within the same Ethernet network, while the IP addresses can be used to communicate across multiple networks, destination on remote network. When the destination IP address is on a remote network, the destination MAC address is that of the default gateway. AP is used by IPv four to associate the IPv four address of the device with the MAC address of the device network interface card, while the ICMP version six, or ICMP v6 is used by the IPv six to associate the IPv six address of the device with the MAC address of the device network interface card. So remember, in IPv four, the process is the app that is used for the Association of MAC address to the network interface card, while in IPv six, the IP ICMP v6 is the process that it will be used to associate the MAC address through the network interface card. If you have access to the neta CAD, please go ahead and do your Packet Tracer lab with associated with this particular module, and I will be posting these Packet Tracer labs on my YouTube channel in the future. So it\'s not going to be part of this lecture video, so I\'m just going to skip through this slide. But if you have access to the DC Connect Academy, you should stop right now and then just go ahead and do this Packet Tracer lab which which is titled identify Mac and IP addresses. You Ava app, a device uses up to determine the destination MAC address of a local device when it is known it\'s a IP v4 address up provides two basic functions, resolving IPv four addresses to a MAC address and maintaining an ARP table of a IPv form to MAC address by simply mapping them. So. So again, I provide two basic functions, resolving IPv four addresses to a MAC address and maintaining an app table of IPv four to MAC address in the device to send a frame, a device will search its app table for a destination, i, p, v4 address and a corresponding MAC address. So. Just like a, you know, like a cam table, the we will have an OP table that will have the destination, I P v4 address and the MAC address associated with that IPv four address, or very these specific IP v4 addresses and the MAC addresses associated with those specific devices. If the packets destination IP v4 address is on the same network, the device will search the ARP table for the destination I P v4 address. If the destination I P v4 address is on a different network, the device will search the ARP table for the I P v4 address of the default gateway. This is very important concept that you should learn. If the destination I P v4 address is found on the on the app table and it is on the same network, the device will search the app table for the destination I P v4 address. But if the destination I P v4 address is on a different network, it the device will search the app table for the IPv four address of the default gateway. So that\'s an important concept that you understand. And if the device locates the I P v4 address, its corresponding MAC address is used as the destination MAC address in the frame. And if there is no op table entry found, then the device sends an OP request so that it can update that up, MAC address, IP address, MAC address relationship. So remember that if there is no op table entry found, then the device sends an app request, and that request is used to update the app table so they can associate that IP address with the device MAC address. There\'s a video that explained this much better using a demonstration, and this video is available to you on your Cisco NetAcad website. If you don\'t have access to Cisco NetAcad, I will post a link in the description for a copy of that video. It\'s called the ARP request. You should go ahead and check it out, and that will explain this much better. So, yeah, that\'s what this slide about. And the next slide there is another video about App operation. It\'s called App operation, app reply. And again, if you have access to Cisco NetAcad, you can go ahead and watch them, or I will leave a link below in the description, and you should watch that video as well. And even in the next slide, we\'re gonna have the app role in remote communications video. It\'s again, a demo created by Cisco NetAcad people, and I have a copy of that available on my YouTube channel. I will leave a link below if you do not have access to your NetAcad account, NetAcad course material, you will be able to watch that. And I will leave also a card on our on this video. It\'s on the top right hand corner. You can click on the cards, and you will see the list of it. So all of these, these three videos, it should appear on the top right hand corner cards of this YouTube video, and you should be able to click on those and watch those removing entries from an OP table. Entries in the OP table are not permanent and are removed when an OP table cache timer expires after a specific period of time. So remember how the OP table get updated with the specific IP address and association associated MAC address, and it use this that app request to get that information so that the table get updated. Well, when the there is a timer that so that those entries get cleared once it\'s not been used for a while. So the destination of the App Cache timer differs depending on the operating system. So Cisco devices may have a certain up table configuration compared to a Windows device and some other device, etc, etc. Up table entries can also be removed manually by the administrator by sending a command to the router or the switch or the you know the end device, what you need to remember is the ARP entries are not permanent and are removed from the cache after a specified period of time, or sometimes when the device gets rebooted. Up Tables on networking devices. So on Cisco Networking devices, especially on routers, you can type the command show ip app. So show ip ARP command, and that will display the app table for the Cisco device. And this is an example of a Cisco router that displaying that information with the show ip app command on Windows. Computers such as Windows 10 and Windows 11 PCs, you can open the command prompt, and then on command prompt you can type up dash a so up space dashing, and that will display your app information the app cable on your Windows PC, and then you can use that for your network administration purposes, app issues, app broadcasting and app spoofing, app requests are received and processed by every device on the local network excessive ARP broadcast can cause some reduction in performance, such as it could actually create less things like network congestion. For example, ARP replies can be spoofed by a threat actor to perform an ARP poisoning attack. Enterprise level switches include mitigation techniques to protect ARP attacks. So I will not go into detail and depth of ARP attacks and how SSU app broadcast could create network congestion. In this lecture, I will post a separate video explaining different network attacks and how you can mitigate them. But for this course, what you need to remember for this module is that there are vulnerabilities with up they include abroad cast, which could create a network congestion, and the other one would be the up spoofing by a threat actor that could cause a app poisoning attacked, and in terms of detail on how they work, I will go over that in a different video for now. Just remember that our broadcasting and app spoofing is a have some vulnerability issues in our network systems. Again, if you have access to your Cisco NetAcad, there is a Packet Tracer lab that you should be doing. I would pause this video, go ahead and do that lab, and then come back and watch the rest. And again, I will make sure to post those Cisco NetAcad labs on my YouTube channel later this week, IPv six and Neighbor Discovery. Again, there is a video made by Cisco NetAcad called IPv six Neighbor Discovery. That video will explain the process of how IPv six perform address resolution using ICMP v6 neighbor solicitation and neighbor advertisement messages. And I will leave a link in the description of this video in case you do not have access to Cisco NetAcad material. And you can also click on the cards at the top right hand corner where you can click on that video and watch it. IPv six Neighbor Discovery messages, the IPv six Neighbor Discovery or nd protocols provide address resolution, router discovery and redirection services, ICMP v6 neighbor solicitation NS and neighbor advertisement. Na, messages are used for device to device messaging such as address resolution, icmpv Six, router, solicitation, RS and router advertisement. Ra, messages are used for messaging between devices and routers for router discovery, ICMP v6 direct messages, using used by routers for better next hop, press selection, each one of these items, I will go in detail later. But for now, for this course, this particular modules. What you need to remember is that the Neighbor Discovery and the protocol provide these items like address, resolution, router, discovery and redirection, and the NS, na RS array, you know what they\'re what. Why did we use them? Use and we use it and what why these items are responsible for in the IPv six Neighbor Discovery messages, IPv six Neighbor Discovery address resolution, IPv six devices uses Neighbor Discovery to receive. All the MAC address of a known IPv six address, ICMP version six neighbor solicitation messages are sent using special Ethernet and IPv six multicast addresses. So that\'s how it actually communicate between IP v6 addresses. So we have IC MP v6 neighbor solicitation message. It would be something like, you know, just like saying, hey, who, whoever has this particular IPv six address, please send me your MAC address. So it\'s like a up message, but for IP v6 and then when that message was received by this particular IP address, in this case, in the PC to it going to reply back saying, Hi, I am that IP address, and my MAC address is so so on and so forth. And then that information get updated when the message being received back from that advertisement message. So we have ICMP v6 solicitation message saying, hey, I need that who has this IP address, please give me that MAC address. Belong to that IP address, and then the person, the device that has that IP address, going to give the ICMP v6 neighbor advertisement message, and that will give that, you know, connect that IP address to that MAC address. So that\'s how it works. Again. This is just briefly going over how IPv six work, and I will go into depth of exactly how IPv six neighbor solicitation and Neighbor Discovery and all of these things work on a later video, but just for now, just remember, this is how IPv six differ from IPv four app messages. There is a packet trace lab activity on your Cisco NetAcad, and if you have an access to your Cisco labs, go ahead. You should be doing that right now. Again, I will post those labs on my YouTube channel later, sometime this week or upcoming weeks, and this is the end of this lecture, and I will quickly go over what we learn in this lecture. We learn that the layer two physical addresses, such as Ethernet MAC addresses, are used to deliver the Data Link Frame with the encapsulated IP packet from one network card to the next state network card. But however, these physical two addresses are being used to communicate between network card to network card on the same network. If the destination IP is on the same network, the destination MAC address will be that of the destination device. When the destination IP address, whether it\'s IPv four, IP v6 it doesn\'t really matter. Is on a remote network, the destination MAC address will be the address of the host default gateway. For example, in your house, the your default gateway going to be your routers interface. An IP v4 device uses up to determine the destination MAC address of a local device when it knows the IPv four address, ARP provides two basic functions. They are resolving IPv four addresses to a MAC address and maintaining a table of IPv four to MAC address mapping, which is we call the ARP table. After the ARP reply is received, the device will add the IPv four address and the corresponding MAC address to its app table, hence updating that up table for each device. And ARP cache timer removes up entries that have not been used for a specific period of time, and that timer changes based on the device that you are using, such as Cisco devices versus dealing devices versus your Windows device. So it\'s a random timer. IPv six does not use up. Instead, it used something called net Neighbor Discovery Protocol to resolve MAC addresses an IPv six device uses ICMP version six Neighbor Discovery to determine the destination MAC address of a local device when it knows its IP v6 address.