1 00:00:09,440 --> 00:00:13,520 In this lab, you need to configure network address, translation or net. 2 00:00:21,170 --> 00:00:21,440 Okay. 3 00:00:21,440 --> 00:00:28,880 So in this lab we've been told to configure the router with dhcp on the internet facing interface. 4 00:00:29,330 --> 00:00:34,070 So on the router I can see that it's just booted up. 5 00:00:37,540 --> 00:00:45,550 So enable first thing I'll do is configure the router with a hostname of let's say write a one per the 6 00:00:45,550 --> 00:00:57,130 diagram interface gigabit 001 IP address and we're going to use DHCP on that interface and I'll know 7 00:00:57,150 --> 00:00:58,480 shut the interface. 8 00:00:59,830 --> 00:01:02,590 So show IP interface brief. 9 00:01:04,230 --> 00:01:06,750 We can see that the interfaces up up. 10 00:01:06,900 --> 00:01:09,240 But no address has been assigned yet. 11 00:01:09,750 --> 00:01:16,890 Notice this link is showing orange, so we may have to wait a while for spending tree to converge. 12 00:01:16,890 --> 00:01:17,640 And there we go. 13 00:01:17,640 --> 00:01:18,690 It's gone green. 14 00:01:19,080 --> 00:01:27,270 In this lab, this DHCP server is allocating addresses to the router, so it may take a while to receive 15 00:01:27,270 --> 00:01:28,350 an IP address. 16 00:01:28,680 --> 00:01:39,150 So while we waiting, I'll configure the inside interface with an IP address of ten 11254 slash 24 and 17 00:01:39,150 --> 00:01:41,160 no, shut the interface. 18 00:01:42,330 --> 00:01:46,710 As you can see here, spanning trees, also converging on the side. 19 00:01:47,070 --> 00:01:54,450 And while that was happening, we've now been allocated an IP address on the gigabyte 001 interface. 20 00:01:57,200 --> 00:01:59,720 So show IP interface brief. 21 00:02:00,110 --> 00:02:03,980 We've got an IP address on the routers internet facing interface. 22 00:02:04,400 --> 00:02:06,620 It was allocated via DHCP. 23 00:02:06,920 --> 00:02:11,930 We've also got an IP address configured on the inside interface. 24 00:02:12,440 --> 00:02:17,000 Can the router ping the DNS server? 25 00:02:18,210 --> 00:02:19,290 Yes, it can. 26 00:02:19,320 --> 00:02:20,400 Can it ping? 27 00:02:20,400 --> 00:02:21,690 Swisscom. 28 00:02:23,250 --> 00:02:25,430 Now I've found with packet trace. 29 00:02:25,470 --> 00:02:31,770 You may have to wait a bit when you do your initial pings, so just be patient and see what it does. 30 00:02:32,220 --> 00:02:35,010 But in this example, I can ping Cisco dot com. 31 00:02:35,370 --> 00:02:37,770 Can I ping facebook.com? 32 00:02:38,630 --> 00:02:41,180 So ping facebook.com. 33 00:02:42,700 --> 00:02:43,900 Yes, I can. 34 00:02:44,020 --> 00:02:44,990 So that's good. 35 00:02:45,010 --> 00:02:52,870 Internet site is working and now we need to configure DHCP on the internal network. 36 00:02:55,190 --> 00:03:08,900 So conf t ip dhcp pool and I'll just call this net network is going to be ten 110 slash 24 mask per 37 00:03:09,320 --> 00:03:15,860 this information default router is going to be ten 11254. 38 00:03:16,730 --> 00:03:21,140 DNS server is going to be Google. 39 00:03:21,560 --> 00:03:22,760 So there we go. 40 00:03:23,240 --> 00:03:24,320 Show run. 41 00:03:24,530 --> 00:03:30,500 That's our DHCP configuration show IP, DHCP pool. 42 00:03:30,950 --> 00:03:32,720 There's the pull information. 43 00:03:33,050 --> 00:03:35,690 We've got IP addresses in this range. 44 00:03:36,530 --> 00:03:39,860 Now the router is using this IP address. 45 00:03:41,260 --> 00:03:47,230 So you don't have to do this for this lab, but in the real world, you're going to want to create an 46 00:03:47,230 --> 00:03:48,520 exclusion range. 47 00:03:48,760 --> 00:03:53,410 So let's exclude IP addresses, say, in this range. 48 00:03:54,710 --> 00:03:58,130 Now remember again, these are challenge labs. 49 00:03:58,460 --> 00:04:01,820 Hopefully you've learned something by watching this video. 50 00:04:01,850 --> 00:04:06,000 If you didn't configure an exclusion range, be careful. 51 00:04:06,020 --> 00:04:10,190 In the real world, you probably want to do that in the exam. 52 00:04:10,430 --> 00:04:13,610 They'll be more specific about what you need to do. 53 00:04:14,480 --> 00:04:19,820 We don't want the Rada allocating its own IP address via DHCP. 54 00:04:19,850 --> 00:04:22,130 That does sometimes happen. 55 00:04:22,820 --> 00:04:25,760 So again, show IP DHCP pool. 56 00:04:27,260 --> 00:04:34,940 The pull range is this, but we've got an exclusion range, so we've excluded the Router's IP address 57 00:04:35,540 --> 00:04:38,060 show IP DHCP binding. 58 00:04:38,360 --> 00:04:42,080 At the moment, no clients have got IP addresses. 59 00:04:42,260 --> 00:04:48,200 So let's go onto one of the clients, go to the desktop, go to command, prompt. 60 00:04:50,410 --> 00:04:51,700 And use the command. 61 00:04:51,730 --> 00:04:52,870 IP config. 62 00:04:52,990 --> 00:04:54,970 No IP addresses allocated. 63 00:04:55,300 --> 00:05:03,740 So let's do a new to force the PC to send out a DHCP request and ask for an IP address. 64 00:05:03,760 --> 00:05:05,410 So there's the IP address. 65 00:05:05,770 --> 00:05:08,190 So can we ping the router? 66 00:05:10,160 --> 00:05:11,330 Yes, we can. 67 00:05:11,930 --> 00:05:14,090 Can we ping the DNS server? 68 00:05:15,980 --> 00:05:17,690 And the answer is no. 69 00:05:17,720 --> 00:05:23,420 And that's because we need to configure network address translation on the router. 70 00:05:24,470 --> 00:05:34,490 So on the router interface gigabit 001 IP, Nat, and this is going to be the outside interface interface 71 00:05:34,490 --> 00:05:36,350 gigabit 000. 72 00:05:36,380 --> 00:05:39,530 This is going to be the inside interface. 73 00:05:40,220 --> 00:05:41,450 So we've configured. 74 00:05:42,430 --> 00:05:44,740 Outside and inside interfaces. 75 00:05:45,520 --> 00:05:54,230 Now we need to use the command IP net and we are netting inside devices based on a source list. 76 00:05:54,250 --> 00:05:55,990 In other words, an access list. 77 00:05:56,630 --> 00:06:01,460 In this example, to keep things simple, I'm going to use access list one. 78 00:06:02,060 --> 00:06:05,750 You could have used a different access list if you wanted to. 79 00:06:06,830 --> 00:06:11,480 Interface is going to be gigabit 001. 80 00:06:11,630 --> 00:06:15,140 And don't forget to add the word overload. 81 00:06:15,320 --> 00:06:19,250 You must overload the interface to enable Pat. 82 00:06:19,940 --> 00:06:26,390 And then the last step is to create an access list where you decide which traffic to permit. 83 00:06:26,810 --> 00:06:30,380 In this example, I'm going to permit any in the real world. 84 00:06:30,380 --> 00:06:32,300 You probably want to limit that. 85 00:06:32,390 --> 00:06:35,630 So don't just permit anything to be netted. 86 00:06:37,660 --> 00:06:40,960 So on the PC now, can we ping the DNS server? 87 00:06:41,050 --> 00:06:42,310 Yes, we can. 88 00:06:45,190 --> 00:06:48,340 So back on the broader show, IP DHCP binding. 89 00:06:49,280 --> 00:06:53,130 This client has been allocated an IP address. 90 00:06:53,150 --> 00:06:55,400 Show IP net translation. 91 00:06:55,820 --> 00:07:00,680 Notice we can see that this client has been netted. 92 00:07:01,550 --> 00:07:08,150 To this IP address, which is the IP address on. 93 00:07:09,520 --> 00:07:11,140 The outside interface. 94 00:07:11,290 --> 00:07:12,970 In other words, the router. 95 00:07:13,890 --> 00:07:25,290 On this interface has been allocated to this IP address via DHCP and the PCs are being netted to that 96 00:07:25,290 --> 00:07:26,240 IP address. 97 00:07:26,250 --> 00:07:32,160 So this PC has been netted to the Router's IP address. 98 00:07:33,580 --> 00:07:37,870 So close the desktop down and open up a web browser. 99 00:07:40,500 --> 00:07:43,860 Can the PC get to Cisco dot com? 100 00:07:44,280 --> 00:07:45,450 Yes, it can. 101 00:07:45,660 --> 00:07:51,450 So Cisco dot com is reachable from the first PC. 102 00:07:51,840 --> 00:07:54,690 What about Facebook dot com? 103 00:07:55,620 --> 00:07:57,330 Facebook is also reachable. 104 00:07:58,230 --> 00:07:59,910 So I'm happy with that. 105 00:07:59,940 --> 00:08:03,210 This PC can access both Cisco and Facebook. 106 00:08:03,390 --> 00:08:05,790 What about the second PC? 107 00:08:06,180 --> 00:08:12,120 So command prompt IP config and no IP address has been allocated. 108 00:08:12,760 --> 00:08:18,130 So what I'm going to do is force the PC to get an IP address through DHCP. 109 00:08:19,160 --> 00:08:21,770 It's now been allocated this IP address. 110 00:08:21,800 --> 00:08:25,460 Can it ping the DNS server? 111 00:08:25,490 --> 00:08:26,570 Yes, it can. 112 00:08:26,600 --> 00:08:28,880 Can it ping Cisco dot com? 113 00:08:28,940 --> 00:08:30,170 Yes, it can. 114 00:08:31,300 --> 00:08:34,419 Can it ping Facebook.com? 115 00:08:34,450 --> 00:08:35,679 Yes, it can. 116 00:08:37,190 --> 00:08:38,960 So I'll go to the web browser. 117 00:08:42,070 --> 00:08:50,680 This PC can access Cisco dot com and it can access Facebook.com. 118 00:08:52,600 --> 00:08:54,580 Let's configure the lost PC. 119 00:08:55,000 --> 00:09:01,750 So desktop command prompt IP config need to get an IP address via DHCP. 120 00:09:02,470 --> 00:09:06,280 So force the PC to request an IP address. 121 00:09:06,310 --> 00:09:07,390 There you go. 122 00:09:10,770 --> 00:09:14,220 So can it ping Cisco dot com? 123 00:09:14,250 --> 00:09:15,050 Yes, it can. 124 00:09:15,060 --> 00:09:18,030 Can it ping facebook.com? 125 00:09:18,060 --> 00:09:19,110 Yes, it can. 126 00:09:20,540 --> 00:09:23,450 And as a last test, I'll open up a web browser. 127 00:09:26,530 --> 00:09:27,850 Facebook.com. 128 00:09:29,620 --> 00:09:30,760 Cisco dot com. 129 00:09:32,130 --> 00:09:33,240 I'm happy with that. 130 00:09:33,270 --> 00:09:39,840 The PCs in the internal network have been allocated IP addresses of via DHCP. 131 00:09:40,260 --> 00:09:48,390 The router has been allocated an IP address of DHCP and the internal PCs can access the internet because 132 00:09:48,480 --> 00:09:53,850 the router is netting the IP addresses. 133 00:09:54,600 --> 00:09:56,790 So show IP net translation. 134 00:09:57,270 --> 00:10:00,660 Here are a whole bunch of net translations. 135 00:10:01,050 --> 00:10:03,270 Notice we've got PCs. 136 00:10:04,360 --> 00:10:09,250 Sending DNS requests to the DNS server support. 137 00:10:09,250 --> 00:10:15,610 53 is DNS and 8.82.8.8 is the DNS server. 138 00:10:16,670 --> 00:10:18,090 We can see a PC. 139 00:10:18,110 --> 00:10:20,180 This is the second PC. 140 00:10:20,210 --> 00:10:26,270 PC one accessing swisscom using HTTP. 141 00:10:26,870 --> 00:10:36,290 So the internal hosts are using random or what are called ephemeral ports, greater than 1023 to access 142 00:10:36,830 --> 00:10:38,330 servers on the internet. 143 00:10:38,630 --> 00:10:55,190 Notice how the inside a local address has a different port number to the inside global address because 144 00:10:55,190 --> 00:10:56,600 we're using pat. 145 00:10:56,630 --> 00:10:58,940 The router needs to differentiate. 146 00:10:59,580 --> 00:11:04,380 Between different translations here they the same. 147 00:11:04,530 --> 00:11:07,680 But notice here we have differences. 148 00:11:08,550 --> 00:11:15,420 The Rada needs to be able to differentiate between different sessions going to the same server. 149 00:11:16,230 --> 00:11:24,680 So here the first host and the second host chose the same ephemeral or random port number. 150 00:11:24,690 --> 00:11:31,560 But the rudder has changed those values to allow it to differentiate between the sessions. 151 00:11:32,280 --> 00:11:38,700 So if traffic comes back to the router going to this destination IP address and port number, the router 152 00:11:38,700 --> 00:11:45,450 knows that it needs to send the traffic to PC one, this PC with this IP address. 153 00:11:45,990 --> 00:11:53,220 But if the traffic comes back from Cisco going to this IP address and port number, so same IP address 154 00:11:53,310 --> 00:11:54,960 but a different port number. 155 00:11:55,110 --> 00:12:01,140 The router knows that it needs to send the traffic to the first PC PC zero. 156 00:12:01,740 --> 00:12:10,950 So that's a nice example of port address translation or Pat creating a unique inside global entries 157 00:12:10,950 --> 00:12:16,680 to allow it to differentiate between different inside local IP addresses. 158 00:12:18,130 --> 00:12:25,600 That is a typical example of what you'll see with a network address translation, but specifically port 159 00:12:25,600 --> 00:12:33,730 address translation where one IP address is being shared between multiple devices on the inside network. 160 00:12:35,190 --> 00:12:38,880 As a last step, I'll save the configuration of the router. 161 00:12:39,240 --> 00:12:40,440 So how did you do? 162 00:12:40,470 --> 00:12:42,600 Were you able to complete the lab? 163 00:12:42,960 --> 00:12:44,430 Did you get it working? 164 00:12:44,790 --> 00:12:48,390 And did you verify that things work properly? 165 00:12:49,080 --> 00:12:51,420 It's important to verify your work. 166 00:12:52,140 --> 00:12:54,480 I want to wish you all the very best.