1 00:00:00,120 --> 00:00:06,270 In previous videos, we configured this topology, we configured an HCP router, we configured spanning 2 00:00:06,300 --> 00:00:13,830 three, we configured IGP on the core switches and this Internet facing router and we've done various 3 00:00:13,830 --> 00:00:16,320 things to optimize the topology. 4 00:00:16,800 --> 00:00:22,410 In this video, I'm going to configure network address translation on router three to enable devices 5 00:00:22,410 --> 00:00:25,500 in our genius three topology to access the internet. 6 00:00:26,220 --> 00:00:33,570 He says rather three, rather three is configured with an IP address on Fast Ethernet zero one and the 7 00:00:33,570 --> 00:00:36,900 IP address is 1921681 124. 8 00:00:37,530 --> 00:00:42,960 Router three has a default gateway of 1921681254. 9 00:00:43,020 --> 00:00:46,740 This is the internet facing router in the cloud. 10 00:00:47,190 --> 00:00:54,960 That router does not have the ability to run routing protocols, so I can't advertise the Ten Network 11 00:00:54,960 --> 00:00:57,690 running within Janus three to that router. 12 00:00:58,260 --> 00:01:04,050 So to get this to work, I'm simply going to enable Nat on router three with this being the outside 13 00:01:04,050 --> 00:01:06,570 interface and this being the inside interface. 14 00:01:07,170 --> 00:01:15,420 Now to be correct with wording, we actually enabling port address translation so that multiple devices 15 00:01:15,420 --> 00:01:19,890 in our topology can be netted to the IP address on this interface. 16 00:01:20,370 --> 00:01:29,070 So on Fost Ethernet zero one, I'm going to use the command IP Nat outside to enable Nat on this interface 17 00:01:29,070 --> 00:01:31,440 and make it be the outside interface. 18 00:01:31,440 --> 00:01:35,040 From a NAT point of view that takes a while to come up. 19 00:01:35,040 --> 00:01:40,170 In June is three, but after a while I should be able to configure this interface as the inside. 20 00:01:40,350 --> 00:01:42,600 And there you go so fast. 21 00:01:42,630 --> 00:01:46,710 Ethernet zero zero IP Nat Insight. 22 00:01:47,220 --> 00:01:52,140 So we've told the router that this interfaces the outside interface and this interface is the inside 23 00:01:52,140 --> 00:01:52,890 interface. 24 00:01:53,490 --> 00:01:57,810 So now we need to configure Nat and we do that by tapping the command ip nat. 25 00:01:58,520 --> 00:01:59,630 Inside. 26 00:01:59,660 --> 00:02:02,480 I want to net devices on the inside network. 27 00:02:02,750 --> 00:02:08,750 And in this case, I want to net source IP addresses based on an access list, which is going to be 28 00:02:08,750 --> 00:02:09,979 access list one. 29 00:02:10,220 --> 00:02:18,800 And we're going to net them onto Interface Fost Ethernet zero one and we're going to enable Pat by using 30 00:02:18,800 --> 00:02:20,480 the overload keyword. 31 00:02:21,110 --> 00:02:27,890 So the next step is to create an access list, which is access list one referenced over here in the 32 00:02:27,890 --> 00:02:29,090 net command. 33 00:02:29,570 --> 00:02:33,230 And I'm going to permit all devices in the Ten Network. 34 00:02:36,850 --> 00:02:40,420 So show run pipe include Nat. 35 00:02:41,690 --> 00:02:44,990 Shows me that we've got Nat configured on the inside interface. 36 00:02:45,020 --> 00:02:50,750 Nat is configured on the outside interface and we overloading the outside interface. 37 00:02:51,200 --> 00:02:56,600 Now, to be precise, we should do this show Run Interface, Fast Ethernet zero zero and we can see 38 00:02:56,600 --> 00:03:04,100 that IP Nat inside is enabled on that interface and IP Nat outside is enabled on Fost Ethernet zero 39 00:03:04,100 --> 00:03:08,000 one show IP Nat translations. 40 00:03:08,030 --> 00:03:16,070 At the moment there are no NAT translations, so let's go on to router one acting as PC one. 41 00:03:16,830 --> 00:03:19,800 And let's see if we can ping google.com. 42 00:03:21,840 --> 00:03:22,530 At the moment. 43 00:03:22,530 --> 00:03:28,560 Notice, please, that it's trying to translate google.com using a broadcast. 44 00:03:28,680 --> 00:03:31,290 And this takes a while to time out. 45 00:03:38,030 --> 00:03:39,890 The reason why is. 46 00:03:40,850 --> 00:03:47,210 The radar is doing a domain lookup now that's not shown by default in the running config, but if I 47 00:03:47,210 --> 00:03:53,330 type no IP domain lookup and then try and ping google.com again. 48 00:03:54,080 --> 00:03:56,690 Notice the ping times out immediately. 49 00:03:57,500 --> 00:04:00,320 So if I use IP domain lookup. 50 00:04:01,510 --> 00:04:03,970 I should specify my DNS server. 51 00:04:04,600 --> 00:04:06,430 So IP name server. 52 00:04:08,030 --> 00:04:10,220 And in this case, I'll specify Google. 53 00:04:11,500 --> 00:04:16,870 When I try and ping google.com in this case, notice it works. 54 00:04:17,459 --> 00:04:24,000 We got a reply from the Google DNS server and we were able to ping google.com. 55 00:04:24,740 --> 00:04:28,910 Rata once traffic is being netted by router three. 56 00:04:29,390 --> 00:04:32,240 So notice we can see the net translations. 57 00:04:32,330 --> 00:04:32,780 Yes. 58 00:04:32,780 --> 00:04:35,630 The connection to the Google DNS server. 59 00:04:35,630 --> 00:04:38,090 And he has the connection to Google. 60 00:04:38,930 --> 00:04:47,780 This is the IP address of router one on the inside interface and this is the netted IP address of router 61 00:04:47,780 --> 00:04:53,120 one, which is the IP address of fast Ethernet zero one as shown over there. 62 00:04:54,100 --> 00:04:55,450 I'll show these together. 63 00:04:58,370 --> 00:04:59,990 So debug IP Nat. 64 00:05:00,990 --> 00:05:02,460 And that's actually on the wrong router. 65 00:05:02,460 --> 00:05:12,150 So on all router three debug IP net and what I'll do now is I will do a ping to Google.com and what 66 00:05:12,150 --> 00:05:16,530 we should see is we should see the net translations taking place and there you go. 67 00:05:17,220 --> 00:05:20,490 Notice Source IP address ten one 1011. 68 00:05:20,700 --> 00:05:25,680 This IP address was translated to 1921681 124. 69 00:05:26,130 --> 00:05:31,290 That's the IP address once again of Fost Ethernet zero one on router three. 70 00:05:32,220 --> 00:05:33,990 Going to Google.com. 71 00:05:34,900 --> 00:05:36,760 The initial ping timed out. 72 00:05:37,270 --> 00:05:38,440 So we saw that there. 73 00:05:38,710 --> 00:05:48,850 But there's the second ping and there's a reply to the ping from Google destination IP address of 121681 74 00:05:48,850 --> 00:05:58,870 124 is translated back to 10.1 10.11 is forwarded through the network to router one show IP net translation 75 00:05:58,870 --> 00:06:03,040 shows me that at the moment there are no net translations they've timed out. 76 00:06:03,880 --> 00:06:08,290 So let's telnet to google.com on port 80. 77 00:06:09,010 --> 00:06:10,780 You can see that it's connected. 78 00:06:11,260 --> 00:06:17,830 So it's opening that connection and in the net translations you can see here's the DNS request to the 79 00:06:17,830 --> 00:06:27,520 DNS server and the reply and he has the connection to the Google server to show IP net translation shows 80 00:06:27,520 --> 00:06:33,550 me the DNS request and this is the connection to the web server. 81 00:06:33,670 --> 00:06:40,630 In other words, google.com on Port Eddie we can see that we are currently connected to the Google server. 82 00:06:40,720 --> 00:06:44,200 I'll press control C on the router press enter. 83 00:06:44,680 --> 00:06:47,470 We can see something happening in the natural translations. 84 00:06:48,670 --> 00:06:54,970 I use control shift six x to jump back to the router because it's keeping the connection open. 85 00:06:54,970 --> 00:06:56,920 So I'll disconnect my connection. 86 00:06:57,930 --> 00:07:04,230 So we've successfully configured Nat in this network, allowing writer one to connect to Google. 87 00:07:04,260 --> 00:07:07,620 Let's do the same on router two acting as PC two. 88 00:07:08,040 --> 00:07:17,190 So on PC two, IP name server will be google ping and let's use another server cisco dot com. 89 00:07:19,540 --> 00:07:27,580 Can see that the query succeeded and we able to ping Cisco dot com what about CNN dot com. 90 00:07:28,780 --> 00:07:32,710 In this case, the pings are being dropped by the server. 91 00:07:33,430 --> 00:07:35,440 So let's try Yahoo! 92 00:07:36,550 --> 00:07:37,390 Dot com. 93 00:07:39,270 --> 00:07:41,370 We can see that the pings succeed. 94 00:07:41,850 --> 00:07:50,010 So we've successfully configured this entire network as well as configured Nat on router three and these 95 00:07:50,010 --> 00:07:54,360 routers acting as PCs can now access devices on the Internet.