1 00:00:06,650 --> 00:00:13,420 Okay so that means I need to configure router 4 and the Internet router so I'll do router 4 first 2 00:00:24,140 --> 00:00:25,230 interface serial 3 00:00:25,280 --> 00:00:27,190 010 4 00:00:27,320 --> 00:00:29,440 that's this interface. 5 00:00:31,670 --> 00:00:37,810 Now in the real world you could use commands such as Show CDP neighbors to verify neighbor connectivity. 6 00:00:37,930 --> 00:00:44,050 If you're not sure how interfaces are connected and you wanna verify interface connectivity. 7 00:00:44,050 --> 00:00:50,200 So this is definitely the local interface connected to the Internet router. 8 00:00:50,680 --> 00:01:00,820 So on that interface, interface serial 010 IP address 192 168 1 117 first IP address and subnet 9 00:01:00,850 --> 00:01:03,820 is one more than the subnet address 10 00:01:07,180 --> 00:01:14,480 and because this is a slash 30 the last IP address is simply the next IP address in that subnet interface 11 00:01:14,490 --> 00:01:15,170 serial. 12 00:01:15,220 --> 00:01:19,300 020 IP address 192 168. 13 00:01:19,400 --> 00:01:30,910 We're in the subnet so it would be 118 1 118 slash 30 mask. 14 00:01:30,940 --> 00:01:35,950 So can we ping the other side. 15 00:01:36,010 --> 00:01:41,030 Yes, we can and we can see that on OSPF neighbor relationship has been established. 16 00:01:41,200 --> 00:01:43,840 So back on router 4 17 00:01:46,860 --> 00:01:49,390 OSPF neighbor relationship is established. 18 00:01:49,560 --> 00:01:59,580 We've learnt a default route via the Internet router so IP domain lookup, IP name server is gonna be 19 00:01:59,580 --> 00:02:10,350 Google ping Cisco.com, we can ping Cisco.com, can we ping Facebook.com, yes, we can. So I've 20 00:02:10,350 --> 00:02:18,540 configured the WAN links and updated them per the new subnets that we have the next step is to configure 21 00:02:19,200 --> 00:02:35,030 the subnet. So we need to use this subnet for this local area network now the way that you work out first 22 00:02:35,030 --> 00:02:46,890 host, last host broadcast is once again first host is simply the next IP address after the subnet. So 23 00:02:46,910 --> 00:02:53,750 binary it would look like that, host portion is set to zeros except for the last bit which is set to 24 00:02:53,750 --> 00:03:02,840 1 but in decimal it's simply add 1 to the network portion. The broadcast would be one less than the next 25 00:03:02,840 --> 00:03:14,630 subnet so the next subnet is 80 so the broadcast would be 79 and to work out the broadcast 26 00:03:14,630 --> 00:03:19,340 portion you fill the host portion with binary ones 27 00:03:22,290 --> 00:03:33,630 and again we can verify that we've done a right 79 it looks like this in binary so 0100 followed 28 00:03:33,630 --> 00:03:44,040 by four ones, so that's correct and then the last hosts in the subnet is 1 less than the broadcast address 29 00:03:44,060 --> 00:03:51,210 so 78 and if you want to work it out in binary you set the host portion to binary ones except for the 30 00:03:51,210 --> 00:03:58,860 last bit which is set to zero, host portion for subnet looks like that filled with zeros broadcast is 31 00:03:58,860 --> 00:04:05,910 filled with ones, first host is filled with zeros except for the last bit which is set to 1, the last host 32 00:04:06,630 --> 00:04:12,720 has it filled with ones except for the last bit which is set to 0 so the last IP address in this subnet 33 00:04:12,750 --> 00:04:15,750 which we need to use on router 4 is 79. 34 00:04:15,840 --> 00:04:18,589 So 192 168 1 79 35 00:04:21,370 --> 00:04:30,970 so on the Ethernet interface connecting to the switch gigabit 000 IP address 192 168 1 36 00:04:31,210 --> 00:04:33,550 and again it should be 78. 37 00:04:36,040 --> 00:04:46,330 Subnet is a slash 28, so slash 28 equals 8 plus 8 plus 8 38 00:04:49,660 --> 00:04:54,550 plus 1 2 3 4 binary ones. 39 00:04:57,370 --> 00:05:08,740 So it's 255 255 255, four binary ones in an octet would look like that followed by four zeros which gives 40 00:05:08,740 --> 00:05:11,560 us 240, so this is 240 41 00:05:15,740 --> 00:05:20,990 if you wanna verify it again in our calculator, 240 looks like that 42 00:05:25,390 --> 00:05:28,240 switch needs to be configured with the 43 00:05:31,350 --> 00:05:38,160 second last IP address. I didn't do that here but it's essentially one less than the last IP address 44 00:05:38,640 --> 00:05:40,950 so the switch needs to be configured with 77 45 00:05:48,290 --> 00:05:53,010 so CONF T interface VLAN 1 IP address 192 168 1 46 00:05:56,670 --> 00:06:14,150 77 slash 28. Can we ping 192 168 1 78 so can the switch ping the router make sure that I've done 47 00:06:14,150 --> 00:06:16,850 it right, so show IP interface brief 48 00:06:19,740 --> 00:06:22,370 switch should hopefully be able to ping itself, 49 00:06:27,100 --> 00:06:28,530 can ping itself. 50 00:06:28,540 --> 00:06:30,340 Let's see if we can ping the router again 51 00:06:39,480 --> 00:06:48,400 on the router show IP interface brief, can we ping ourselves, can we ping the switch. 52 00:06:59,010 --> 00:07:01,820 Now notice the switch has some old configuration on it. 53 00:07:11,700 --> 00:07:18,510 So that may be causing problems sometimes in packet tracer when you make changes things break you may 54 00:07:18,510 --> 00:07:24,940 have to restart packet tracer let's just make sure that I haven't done something dumb that all looks 55 00:07:24,940 --> 00:07:33,280 right, that all looks right shows CDP neighbor details we can see the Internet router 56 00:07:36,340 --> 00:07:40,300 we can also see the switch with the correct IP address. 57 00:07:43,650 --> 00:07:52,820 Local port is this, port on the other side is that, on the side shows CDP neighbors we can see the router 58 00:07:53,210 --> 00:08:02,150 on gigabit 101 that looks good let's see if I've done something wrong, what I'm gonna do at this point 59 00:08:02,150 --> 00:08:09,530 is save packet trace and started up again and see if that solves the problem otherwise, I'll check if 60 00:08:09,530 --> 00:08:15,410 I made a mistake, packet tracer has booted up again here's the router 61 00:08:18,790 --> 00:08:30,850 router 4, show run just to confirm that this IP address 192 168 1 78 slash 240 is configured on the 62 00:08:30,850 --> 00:08:31,330 router 63 00:08:35,340 --> 00:08:38,460 and on the switch, switch 3 64 00:08:45,850 --> 00:08:58,390 show run this IP address 192 168 1 77 slash 28 is configured on the switch that's the 65 00:08:59,020 --> 00:09:08,260 second last IP address so ping 192 168 1 77 switch can ping itself cannot ping the router 66 00:09:11,480 --> 00:09:12,770 still having problems. 67 00:09:19,910 --> 00:09:22,520 I'm gonna remove this default gateway command. 68 00:09:22,600 --> 00:09:24,430 Change it IP default gateway 69 00:09:28,930 --> 00:09:34,220 192 168 1 78 70 00:09:34,380 --> 00:09:37,020 Let's see if that solves the problems 71 00:09:39,630 --> 00:09:41,520 and it did, on the real world. 72 00:09:41,520 --> 00:09:44,070 That's not correct, in the real world 73 00:09:44,160 --> 00:09:50,970 you don't need a default gateway to access a local device but that's a problem in packet tracer. 74 00:09:50,970 --> 00:09:55,930 So the issue here was the switch wasn't working per 75 00:09:56,070 --> 00:10:02,460 a real switch in the real world you wouldn't have to do that even though the default gateway is wrong 76 00:10:03,390 --> 00:10:06,180 because they are on the same subnet, 77 00:10:06,630 --> 00:10:10,100 they would still work. 78 00:10:10,950 --> 00:10:13,580 In other words they'd still be able to ping each other. 79 00:10:13,770 --> 00:10:16,660 Can the switch now ping Cisco.com. 80 00:10:16,830 --> 00:10:26,890 Now I've rebooted Packet Tracer so it may take it a while to sort itself out, packet tracer is great 81 00:10:27,130 --> 00:10:35,350 but it does sometimes do things that are not real-world and sometimes has weird issues but at least 82 00:10:35,350 --> 00:10:38,580 it gives us the ability to test things and to learn. 83 00:10:39,430 --> 00:10:41,710 Okay, so the switch can now ping Cisco.com 84 00:10:41,710 --> 00:10:42,760 So that's good, 85 00:10:42,790 --> 00:10:46,600 We have IP connectivity from the switch to the Internet. 86 00:10:46,600 --> 00:10:53,920 We then need to configure the PCs with the first IP addresses in the subnet. 87 00:10:54,020 --> 00:10:57,500 So on the PC FastEthernet zero interface 88 00:10:57,760 --> 00:11:01,420 192 168 1 89 00:11:01,690 --> 00:11:06,550 IP address is gonna be 65, first IP address in the subnet. 90 00:11:06,550 --> 00:11:21,100 So 65 subnet mask is 255 255 255 240, default gateway is gonna be 192 168 1 78 DNS server 91 00:11:21,610 --> 00:11:24,750 is gonna be Google. 92 00:11:24,970 --> 00:11:31,140 So hopefully this PC should be able to ping Cisco.com which it can and hopefully should be 93 00:11:31,140 --> 00:11:36,670 able to browse to Cisco.com which it can 94 00:11:36,720 --> 00:11:40,050 and what about facebook.com. 95 00:11:40,050 --> 00:11:43,890 You can also browse to facebook.com so that works well. 96 00:11:44,160 --> 00:11:57,470 Next PC, IP address is gonna be statically configured 192 168 1, it's gonna be 66 next IP address in 97 00:11:57,470 --> 00:12:11,370 the subnet 255 255 255 240 default gateway is gonna be 192 168 1 78, so can it ping Cisco.com 98 00:12:11,370 --> 00:12:14,370 spelled that wrong 99 00:12:17,350 --> 00:12:22,670 can't find the domain name let's just check that I configured the DNS forgot to do that. 100 00:12:22,670 --> 00:12:33,350 So DNS needs to be configured it can ping Cisco.com can it get to Cisco.com? Yes, it can. 101 00:12:33,470 --> 00:12:35,760 Can it get to facebook.com? 102 00:12:35,780 --> 00:12:37,180 Yes, it can. 103 00:12:37,370 --> 00:12:50,970 And then the last PC in that subnet needs a static IP address of 192 168 1 67, 255 255 255 104 00:12:50,970 --> 00:13:05,200 240, default gateways 192 168 1 78, DNS server is Google we should be able to ping Cisco.com 105 00:13:05,320 --> 00:13:13,210 which we can and hopefully at this point we'll be able to browse to Cisco which we can and browse to 106 00:13:13,210 --> 00:13:15,760 facebook.com which we can. 107 00:13:15,760 --> 00:13:19,670 So I've successfully completed this lab. 108 00:13:20,080 --> 00:13:30,220 I've taken the subnet and broken it up into as many subnets as possible each having 8 hosts per subnet. 109 00:13:30,220 --> 00:13:31,840 That's what we did there. 110 00:13:31,930 --> 00:13:41,530 Then I took the last subnet and subnet ID it again and used these two subnets for the WAN links. 111 00:13:41,680 --> 00:13:50,500 Notice we still have these two subnets available and these two subnets available, so we've conserved 112 00:13:50,530 --> 00:13:56,500 IP addresses in our network rather than using a slash 26 which is very wasteful. 113 00:13:56,500 --> 00:14:05,230 On a WAN link we're using slash 30s on two WAN links and we've used one of the subnets for a site and 114 00:14:05,230 --> 00:14:06,280 we've got more spare. 115 00:14:06,610 --> 00:14:10,040 So what we should do is subnet this one as well. 116 00:14:10,120 --> 00:14:15,580 So what you would do in the real world is make this a slash 30 and better utilize your IP addresses 117 00:14:16,420 --> 00:14:18,250 but that's okay for this lab. 118 00:14:18,340 --> 00:14:19,990 I've completed this lab. 119 00:14:20,020 --> 00:14:21,100 How did you do? 120 00:14:21,100 --> 00:14:24,300 Were you able to complete the lab yourself. 121 00:14:24,310 --> 00:14:27,850 IP subnetting is really important for the CCNA exam. 122 00:14:27,880 --> 00:14:34,750 Make sure you understand how to use variable length, subnet masks like I've done here. 123 00:14:34,750 --> 00:14:40,090 Make sure that you understand how to subnet and how to allocate IP addresses to devices in subnets.