1 00:00:09,070 --> 00:00:17,320 This is one of multiple videos discussing that or network address translation in the video we are troubleshooting 2 00:00:17,590 --> 00:00:19,240 a next issue. 3 00:00:19,300 --> 00:00:27,190 We've been told that hosts on the inside network in other words these hosts which are being represented 4 00:00:27,190 --> 00:00:37,620 by one wrote a four and wrote a five I'm not able to ping 8 8 8 8 which is a Google DNS server. 5 00:00:37,840 --> 00:00:42,410 And in this example that's being represented by router 3. 6 00:00:42,480 --> 00:00:47,140 So we have the inside and the outside network router. 7 00:00:47,180 --> 00:00:57,990 Two in this topology is on next to Rodda So lets connect to of one which is acting as Host 1 and see 8 00:00:57,990 --> 00:01:05,700 if it can ping 8 8 8 8 getting an unreachable message in the output here. 9 00:01:06,030 --> 00:01:09,900 Let's have a look at the writing table. 10 00:01:10,050 --> 00:01:19,620 The Shradha has a default gateway configured as 10 datt 1 to 1 2 2 5 4 that is wrote 2 in the typology 11 00:01:20,580 --> 00:01:28,820 which is on that Rodda Serrato one acting as host one is able to get to the NAT router but it doesn't 12 00:01:28,820 --> 00:01:33,390 look like it's able to get to the Google Rodda. 13 00:01:33,630 --> 00:01:38,130 So you can see in the output here it's reached 10 1 1 2 5 4. 14 00:01:38,280 --> 00:01:41,490 But it doesn't look like it can get any further. 15 00:01:41,550 --> 00:01:42,510 Now just speed things up. 16 00:01:42,510 --> 00:01:45,460 I'm going to use the no IP domain lookup command. 17 00:01:47,050 --> 00:01:48,900 And then let's do that trace again. 18 00:01:49,060 --> 00:01:55,890 So you can see it gets to default gateway but can't get any further than that. 19 00:01:55,940 --> 00:02:02,290 Let's have a look at the default gateway and see what's happening with the net translations. 20 00:02:02,310 --> 00:02:07,240 So this is rodded to show IP not translations. 21 00:02:07,320 --> 00:02:09,570 There are no net translations at the moment. 22 00:02:09,750 --> 00:02:11,890 Show IP not statistics. 23 00:02:13,100 --> 00:02:19,820 So looking at the statistics we can see that they have been translations in the past. 24 00:02:19,820 --> 00:02:20,840 Outside interfaces. 25 00:02:20,860 --> 00:02:30,010 Gigabit is 0 1 which is this interface facing the Rodda acting as Google inside interfaces or gigabit 26 00:02:30,010 --> 00:02:33,310 to 0 0 0 2 and 0 3. 27 00:02:33,330 --> 00:02:40,350 In other words these interfaces over here a dynamic mapping has been configured for inside source address 28 00:02:40,350 --> 00:02:41,790 translation. 29 00:02:41,880 --> 00:02:48,750 We've got a access list pointing to a net pool called Nat Poole. 30 00:02:48,750 --> 00:02:51,790 Can any of the other internal Rajahs ping Google. 31 00:02:51,870 --> 00:03:04,750 So this is Route for all so getting unreachable to a debug IP not on route to we see a problem here 32 00:03:04,760 --> 00:03:09,260 saying that NAT translation failed dropping the packet. 33 00:03:09,260 --> 00:03:13,600 So we getting a dropped packet from 10 1 to 2 34 00:03:16,320 --> 00:03:23,000 which is this router Let's have a look at Route one again. 35 00:03:23,060 --> 00:03:26,270 So this product couldn't trace to Google. 36 00:03:26,420 --> 00:03:28,090 Let's see what happens here. 37 00:03:28,840 --> 00:03:33,120 We also are getting a NAT translation failure. 38 00:03:33,270 --> 00:03:42,460 So let's have a look at the configuration gigabit 0 one is configured with this IP address and it's 39 00:03:42,460 --> 00:03:49,960 configured as the outside address show run interface geek if it's 0 0 as an example. 40 00:03:49,960 --> 00:03:58,160 It's configured with this IP address and it's configured as the inside not to address show run piping 41 00:03:58,210 --> 00:04:00,150 Plude Nat. 42 00:04:00,170 --> 00:04:05,780 So these are the statements on the interfaces telling us which interfaces are inside and outside. 43 00:04:06,050 --> 00:04:10,930 If I do a show run pipe include access. 44 00:04:11,170 --> 00:04:15,110 Can you see the problem. 45 00:04:15,120 --> 00:04:20,670 OK so I notice the statement IP Nat inside source list 1 Paul Knecht. 46 00:04:20,730 --> 00:04:26,940 Paul in other words we are saying that any traffic matching access list one which is permitting anything 47 00:04:27,300 --> 00:04:32,170 will be netted according to this Nat Poole called Nat Poole. 48 00:04:32,520 --> 00:04:39,950 But notice your IP Nat Poole Nat pole instead of a NAT poll is being used. 49 00:04:40,350 --> 00:04:47,300 So everything else looks good except we've got a spelling mistake on the Nat Poole name. 50 00:04:47,480 --> 00:04:49,940 So let's fix that. 51 00:04:50,100 --> 00:04:51,430 No no. 52 00:04:51,440 --> 00:04:55,700 Remove this command. 53 00:04:55,760 --> 00:04:57,530 So no IP net Poole. 54 00:04:57,890 --> 00:05:01,180 And then I'll edit that to make it correct. 55 00:05:01,250 --> 00:05:02,760 So at the extra O. 56 00:05:03,290 --> 00:05:14,320 So show run piping clewed not this Nat Poole reference by the IP that statement now exists in the configuration. 57 00:05:14,320 --> 00:05:16,100 So let's try to do that ping again. 58 00:05:16,210 --> 00:05:27,800 Ping succeeds and notice we can see that 10 1 1 1 which is this Rodda was nattered 2 8 2 8 8 8 to 10 59 00:05:28,460 --> 00:05:34,850 which is the first IP address in the net pool for traffic going to 8 8 8 8 8. 60 00:05:34,910 --> 00:05:42,470 And then when the return traffic came back the address was invited back to the internal address of the 61 00:05:42,470 --> 00:05:45,530 router show IP Nat translation. 62 00:05:45,530 --> 00:05:47,100 Shows us that. 63 00:05:47,150 --> 00:05:53,150 So inside a local address is being netted to the inside global address the outside addresses not being 64 00:05:53,160 --> 00:06:06,020 nattered So host one can ping Google and we see the NAT translation taking place host for can also ping 65 00:06:06,440 --> 00:06:08,150 Google but come. 66 00:06:08,280 --> 00:06:12,290 And we've also got another host to host five if you like. 67 00:06:12,630 --> 00:06:18,410 Well Rodda five acting as our third host. 68 00:06:18,600 --> 00:06:25,490 Can it ping Google yes it can. 69 00:06:25,490 --> 00:06:27,160 So that was an example of how to troubleshoot. 70 00:06:27,170 --> 00:06:34,670 Not even to this video if it's been a benefit to you please like it and please subscribe to my YouTube 71 00:06:34,670 --> 00:06:35,410 channel. 72 00:06:35,740 --> 00:06:37,340 I wish you all the very best.