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 download this practice lab from the link in the description and try it out yourself in packet tracer. In this lab we will practice subnetting using VLSM, variable-length subnet masks. This will be very similar to the end of day 15’s lecture video, you will subnet a class C network into 5 subnets of different sizes. So, I highly recommend that you try to complete this lab first, before watching this video to check your answers. We are required to subnet the 192.168.5.0/24 network to provide sufficient addressing for each LAN, as well as the point-to-point connection between R1 and R2. We will follow the same process that I introduced in Day 15’s lecture video. Assign the largest subnet at the start of the address space, and then the second largest, etc, until you have assigned each subnet. So, that means we will assign subnets in this order: LAN2, LAN1, LAN3, LAN4, and finally the point-to-point link. The instructions also say to assign the first usable address to the PC in each LAN, and the last usable address to the router. Finally, we should configure static routes so that hosts in each LAN can reach hosts in the other LANs. So let’s get started with LAN2. I hope you’ve already solved this lab and are just watching this video to check, since I won’t go step-by-step through each calculation like in the lecture video. Let me tab out to this document where I’ve calculated all of the answers. So, for LAN2 we must use a /25 prefix length. LAN2 only requires 64 hosts, and as I’ve written below a /25 prefix length allows for 126, but if we used a /26 prefix length there would only be enough addresses for 62 hosts because we have to subtract 2 for the network and broadcast addresses. So, LAN2’s network address is 192.168.5.0, and its broadcast address is 192.168.5.127, both /25. Let’s assign the addresses to PC2 and R1. Let me go on R1 first. First, enter privileged exec mode with ENABLE. Then, enter global config mode with CONFIGURE TERMINAL. R1’s Gigabitethernet0/1 interface is in LAN2, so INTERFACE G0/1 to configure it. The broadcast address is 192.168.5.127, so let’s configure R1’s IP address as one below it, the last usable address. IP ADDRESS 192.168.5.126, and for a /25 prefix length the subnet mask will be 255.255.255.128. Also, let’s enable the interface with NO SHUTDOWN. Let’s confirm our configuration. DO SHOW IP INTERFACE G0/1. The ‘SHOW IP INTERFACE’ command shows various information about the interface, primarily layer 3 information. You can see here that the IP address has been configured correctly. You may notice the broadcast address of 255.255.255.255. This address basically functions the same as the subnet broadcast address of 192.168.5.127, and it can be used for any network. When we configure other IP addresses and use this SHOW IP INTERFACE command, those other interfaces will display the same broadcast address too. Keep in mind, if a host sends a broadcast to 255.255.255.255, it won't be sent to ALL networks, it will still stay in the local subnet, and a router will NOT route it to other networks. The subnet broadcast address however, 192.168.5.127 in this case, can be used by hosts in other subnets to send a broadcast to this subnet. Anyway I think I’ll explain that in a lecture video in the future, so don’t worry about it. I just wanted to explain it since you can see it here. Okay, now let’s configure PC2. Click on config, then first set the default gateway to R1, 192.168.5.126. Then, click on fastethernet0, and set the IP address and subnet mask. The first usable address is 192.168.5.1. After you enter it you can press tab, and notice it tries to fill in the subnet mask for me, however since this isn’t a classful network, it’s a subnet, let me change the last octet to 128. Okay, that’s all for this subnet. The second largest subnet is LAN1. Let me go back to my document and let’s look at LAN1. So, for LAN1 we will use a /26 subnet mask. LAN1 requires 45 hosts, and a /26 subnet mask allows 62. The network address is the next address after LAN2’s broadcast address, so it's 192.168.5.128/26. The broadcast address, with all host bits set to 1, is 192.168.5.191. Let’s configure the router and the PC. I’ll go back to R1 first. Let’s configure the G0/0 interface with the last usable address. INTERFACE G0/0. IP ADDRESSS 192.168.5.190 255.255.255.192, which is the subnet mask for a /26 prefix length. Enable the interface with NO SHUTDOWN, and let’s check. DO SHOW IP INTERFACE G0/0. The IP address is correct, and you can see the same broadcast address 255.255.255.255. Next let’s configure PC1. Click on config, set the gateway to 192.168.5.190. Then click on fastethernet0, set the ip address to 192.168.5.129, hit tab, and then change the last octet to 192, for the /26 prefix length. That’s all for LAN1. Next up is LAN3. Let’s go back to that document. So, for LAN3 we will use a /28 prefix length, which allows for 14 hosts, exactly the number we need for LAN3. Keep in mind, in real networking you want to leave some extra room for future growth, but when taking a test do EXACTLY as the instructions say. The network address is the next address after LAN1’s broadcast address, so it’s 192.168.5.192/28. The broadcast address is 192.168.5.207. Let’s go configure R2. Enable. Conf t. Interface g0/0. Let’s configure the last usable address here. IP ADDRESS 192.168.5.206 255.255.255.240, which is the subnet mask for a /28 network. Enable the interface with NO SHUTDOWN, and let’s confirm. DO SHOW IP INTERFACE g0/0. So, the IP address is correct. Next let’s configure PC3. Click on config. Set the gateway address to 192.168.5.206. Click on fastethernet0, IP address of 192.168.5.193. Hit tab, and then change the last octet here to 240. Okay, that’s all for LAN3. Next is LAN4. Let’s go back to that document. So, for LAN4 we will actually use a /28 also. LAN4 requires only 9 hosts, so a /29 prefix length, which allows only 6 hosts, would be too small. The network address is 192.168.5.208, and broadcast address is 192.168.5.223. Now let’s go back to R2 and configure it’s G0/1 interface. Interface g0/1. Ip address 192.168.5.222 255.255.255.240. Enable the interface with NO SHUTDOWN. And let’s check, DO SHOW IP INTERFACE G0/1. Okay, the IP address looks correct. Let’s go to PC4. config. Set the gateway to R2’s address, 192.168.5.222. fastethernet0, set the IP address to the first usable address, 192.168.5.209, hit tab, and change the last octet of the subnet mask to 240. That’s all for LAN4. The last subnet we have to assign is the point-to-point connection between R1 and R2. Let’s go back to the document. So, we can use a /30 or /31, I’m going to go with /30, I just think it’s the safe option to go with on a Cisco test. So, the network address is 192.168.5.224, and broadcast address is 192.168.5.227. We’ll use the first usable address for R1, and last usable address for R2. In fact, those are the only two usable addresses. Let’s go on R1. Interface g0/0/0. Ip address 192.168.5.225 255.255.255.252. Enable the interface with NO SHUTDOWN. Let’s check it. DO SHOW IP INTERFACE G0/0/0. Okay, the address looks good. Now let’s go on R2. interface g0/0/0. IP ADDRESS 192.168.5.226 255.255.255.252. And enable it with NO SHUTDOWN. And finally let's confirm. DO SHOW IP INTERFACE G0/0/0. Okay, no problems here. Now, the last step is to configure static routes on each router. Each router has three connected networks. Those are the point-to-point link, and LAN1 and LAN2 for R1, or LAN3 and LAN4 for R2. So, we’ll have to configure two static routes for each router. First, let’s configure the routes to LAN1 and LAN2 here on R2. Exit, to go back to global config mode. First, LAN1. IP ROUTE, then LAN1’s network address, 192.168.5.128 255.255.255.192, then let me use the question mark here. Note that you can either specify the exit interface of this router, or the IP address of the next hop. I’ll go with the next hop, 192.168.5.225. Okay, that’s it. Next, to LAN2, same thing. IP ROUTE 192.168.5.0 255.255.255.128, and then the next hop of 192.168.5.225. Let’s check the route table. DO SHOW IP ROUTE. Okay, you can see the connected and local routes here, and then the two static routes we just configured. Let’s go on R1 and configure the routes to LAN3 and LAN4. First, exit to return to global config mode. So, the route to LAN 3, first. IP ROUTE 192.168.5.192 255.255.255.240, then the next hop of 192.168.5.226. Okay, now to LAN4. IP ROUTE 192.168.5.208 255.255.255.240 192.168.5.226. Let’s check the route table. DO SHOW IP ROUTE. Okay, looks like R1 has all of the routes it should. Let’s just try a ping from PC1 to another PC, let’s try PC4, to make sure our routes work. Really, you should try to ping all other PCs but I’ll just show one. Okay, so from PC1’s CLI, let’s ping to PC4. PING 192.168.5.209...now, because the ARP process hasn’t completed yet there may be a few failures, but if I keep talking you should see that PC1 can now reach PC4. Okay, so we have successfully subnetted and configured a network, and then configured static routes to provide reachability. That’s all for this lab. Thank you for watching. 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