WEBVTT 1 00:00.000 --> 00:04.480 All right, so regarding the actual traffic flow and what's going on, 2 00:04.480 --> 00:07.880 I always like to do a visual representation of that traffic flow. 3 00:07.880 --> 00:11.200 So let's imagine that you and I are sitting at this VM at 10, 10, 0, 10. 4 00:11.200 --> 00:14.640 The first thing it could be is, does this computer have a valid IP address? 5 00:14.640 --> 00:17.120 So we check out the IP address on the platform we're at, 6 00:17.120 --> 00:20.940 whether it's a Macintosh or it's a Windows computer or Linux verify its IP 7 00:20.940 --> 00:21.320 address, 8 00:21.320 --> 00:25.120 and also verify that it has a default gateway because we're trying to reach 9 00:25.120 --> 00:26.880 something that's not on the local subnet. 10 00:26.880 --> 00:29.840 So I'd verify, in this topology, for example, 11 00:29.840 --> 00:32.720 maybe we're using .1 here at this gateway one. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 11 00:29.840 --> 00:32.720 maybe we're using .1 here at this gateway one. 12 00:32.720 --> 00:36.480 So it would go ahead and have a default gateway pointed to .1. 13 00:36.480 --> 00:39.720 And then from a routing perspective, I just want to make sure that the routing 14 00:39.720 --> 00:43.480 tables here on this gateway and the tier zero gateway and all the rest, 15 00:43.480 --> 00:47.120 make sure that they all have a route, either a default route here or a 16 00:47.120 --> 00:50.680 connected route here that lead to that 10, 90, zero address space. 17 00:50.680 --> 00:54.930 I would also probably use a tool like Trace or some flavor of that, like Trace 18 00:54.930 --> 00:55.280 Route, 19 00:55.280 --> 00:59.040 just to verify the path that the packets are taking as they go through the 20 00:59.040 --> 00:59.560 network. 21 00:59.560 --> 01:02.000 And that way it can help us identify where it stopped. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 21 00:59.560 --> 01:02.000 And that way it can help us identify where it stopped. 22 01:02.000 --> 01:04.600 For example, did it make it pass the gateway one? 23 01:04.600 --> 01:06.400 Did it make it pass the tier zero gateway? 24 01:06.400 --> 01:09.430 And that can also give us some clues about as far as how far it's making it 25 01:09.430 --> 01:10.320 through the network. 26 01:10.320 --> 01:15.230 We could also use the NSX manager as a tool to help us verify the path, for 27 01:15.230 --> 01:18.600 example, to 10, 90, 0.1 and see the output there. 28 01:18.600 --> 01:22.330 So let's presume for the sake of this discussion that the routing here on these 29 01:22.330 --> 01:24.400 three gateways is all set up correctly. 30 01:24.400 --> 01:27.040 The gateway on the client machine is also set up correctly. 31 01:27.040 --> 01:29.160 So if those are all correct, what else could it be? 32 01:29.320 --> 01:33.520 Well, if the client forwards the packet and going to 10, 90, 0, 1, it goes to WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 32 01:29.320 --> 01:33.520 Well, if the client forwards the packet and going to 10, 90, 0, 1, it goes to 33 01:33.520 --> 01:35.160 gateway one, it goes to tier zero. 34 01:35.160 --> 01:39.200 And then it actually goes to this gateway up here, this router, then the router 35 01:39.200 --> 01:40.640 is going to need to respond back, 36 01:40.640 --> 01:42.080 assuming we're not doing that yet. 37 01:42.080 --> 01:45.360 It's going to need to respond back to the 10, 10, 0, dot 10 address. 38 01:45.360 --> 01:48.000 So this device right here is going to look at this routing table. 39 01:48.000 --> 01:51.600 And it's at that point, unless we've actually set up specific routing 40 01:51.600 --> 01:55.320 instructions on this router or are using a dynamic routing protocol. 41 01:55.320 --> 01:58.340 I call it OSPF to train this router about how to forward back to these networks 42 01:58.340 --> 01:58.640 . 43 01:58.960 --> 02:02.440 That's very likely the reason we're not getting the responses back because this WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 43 01:58.960 --> 02:02.440 That's very likely the reason we're not getting the responses back because this 44 02:02.440 --> 02:05.560 router probably has a default route that goes out this way towards the internet 45 02:05.560 --> 02:08.760 and doesn't have these specific routes going back to the 10, 10 network. 46 02:08.760 --> 02:11.860 So to verify that we could go to this external router based on whatever 47 02:11.860 --> 02:14.760 platform it is, Juniper, HP, Cisco, etc. 48 02:14.760 --> 02:18.190 Take a look at that router and then take a look at the routing table and see 49 02:18.190 --> 02:22.360 whether or not it has routes for the 10, 10, 0 network that would lead back 50 02:22.360 --> 02:23.160 down in this direction. 51 02:23.160 --> 02:25.400 And if it doesn't, we could then go ahead and fix it. 52 02:25.640 --> 02:28.840 We're getting solutions. We could do static routes and say, hey, dear Mr. 53 02:28.840 --> 02:31.160 external router to get to the 10, 10, 0 network. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 53 02:28.840 --> 02:31.160 external router to get to the 10, 10, 0 network. 54 02:31.160 --> 02:34.230 Go ahead and forward it down here to Gateway 0 to this IP address here on the 55 02:34.230 --> 02:37.400 segment or even better yet, we could use OSPF. 56 02:37.400 --> 02:40.680 So if we use the OSPF between here and here, we could train our tier zero 57 02:40.680 --> 02:45.070 gateway to advertise these subnets, the 10, 10, 0 network and the 10, 20 58 02:45.070 --> 02:47.720 network via OSPF through redistribution. 59 02:47.720 --> 02:50.840 And that way this router right here would know, Oh, to reach the 10, 10 network 60 02:50.840 --> 02:51.080 . 61 02:51.080 --> 02:54.200 I need to send packets this way or to reach the 10, 20 network. 62 02:54.200 --> 02:57.860 Again, I need to forward pack it this way at which point our tier zero gateway 63 02:57.860 --> 03:00.910 would make the appropriate forwarding decision down to the appropriate tier one WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 63 02:57.860 --> 03:00.910 would make the appropriate forwarding decision down to the appropriate tier one 64 03:00.910 --> 03:03.320 gateway and then forward it down to the final destination. 65 03:03.320 --> 03:07.460 And one other element it could be it could be that on these tier one gateways, 66 03:07.460 --> 03:11.200 if we didn't check the box, it says, I want to go ahead and advertise connected 67 03:11.200 --> 03:13.120 subnets up to the tier zero router. 68 03:13.280 --> 03:17.350 That could also cause a problem because even if we redistribute tier one routes 69 03:17.350 --> 03:21.580 on our tier zero gateway into OSPF, if these tier ones were never configured to 70 03:21.580 --> 03:25.400 advertise those directly connected networks up to the tier zero, then we'd have 71 03:25.400 --> 03:26.160 two problems. 72 03:26.160 --> 03:29.410 This gateway zero wouldn't know how to reach the 10, 10, 10, 20 and our 73 03:29.410 --> 03:31.600 external gateway would not have those routes either. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 73 03:29.410 --> 03:31.600 external gateway would not have those routes either. 74 03:31.600 --> 03:35.510 So thank you for taking a couple minutes to walk through this challenge with me 75 03:35.510 --> 03:39.340 regarding a customer who didn't have full connectivity because of a lack of 76 03:39.340 --> 03:43.000 routes because that gave us an opportunity to remind ourselves the importance 77 03:43.000 --> 03:43.200 of 78 03:43.200 --> 03:48.080 OSPF in an NSX to physical world environment and that is to share the routes so 79 03:48.080 --> 03:51.550 that our routing tables are accurate, both on the NSX side and also on the 80 03:51.550 --> 03:53.520 physical network side as well. 81 03:53.520 --> 03:57.310 So again, thanks for joining me in a set of videos and also you my friend in 82 03:57.310 --> 03:58.560 the very next skill. 83 03:58.560 --> 04:02.830 Until then, I hope this has been informative and I'd like to thank you for WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 83 03:58.560 --> 04:02.830 Until then, I hope this has been informative and I'd like to thank you for 84 04:02.830 --> 04:03.240 viewing.