1 00:00:00,680 --> 00:00:06,410 In the real world, you would never plug a hub between two switches because it will degrade your network 2 00:00:06,410 --> 00:00:07,310 dramatically. 3 00:00:07,610 --> 00:00:12,500 In this example, we've only got the hub in the topology so that we can capture traffic using Wireshark. 4 00:00:12,800 --> 00:00:18,440 You would generally have a direct link between the two switches as shown here in our topology. 5 00:00:18,440 --> 00:00:25,160 I've shut that port down to force all traffic to go via the hub so that we can see what's taking place. 6 00:00:25,520 --> 00:00:31,460 If I enable this port spanning tree will block one of these ports so we won't be able to see the traffic. 7 00:00:31,760 --> 00:00:38,240 So at the moment, PC one can ping, PC three PC to can ping PC four, but they can't ping each other. 8 00:00:38,990 --> 00:00:43,910 So let's set up switch one as our interval and router. 9 00:00:44,720 --> 00:00:46,520 So on switch one. 10 00:00:47,640 --> 00:00:50,070 Show IP interface brief. 11 00:00:50,730 --> 00:00:54,810 At the moment we have an IP address configured on VLAN one and VLAN two. 12 00:00:55,050 --> 00:01:02,820 Now rather one and router three are still using the IP addressing of VLAN one. 13 00:01:03,590 --> 00:01:05,060 Which is bad practice. 14 00:01:05,790 --> 00:01:09,180 We can see that on router one show IP interface brief. 15 00:01:11,090 --> 00:01:14,130 Notice the IP address of this device is ten 111. 16 00:01:14,480 --> 00:01:19,490 So I'll change that to put it into VLAN 11. 17 00:01:19,490 --> 00:01:22,400 So IP address 10.18 11.1. 18 00:01:23,240 --> 00:01:24,110 It's just good practice. 19 00:01:24,110 --> 00:01:32,270 You could keep those IP addresses, but it will get confusing when you set up a management VLAN, so 20 00:01:32,270 --> 00:01:34,610 I'll just configure it correctly at this point. 21 00:01:36,240 --> 00:01:37,370 On Router three. 22 00:01:37,380 --> 00:01:41,610 Currently, the IP address is 10.1 to 1.3. 23 00:01:41,880 --> 00:01:53,460 So change that to 10.1 or 11.3 and set up the default gateway ten at 1.11 to 5 four. 24 00:01:53,910 --> 00:01:58,920 And then we need to configure VLAN 11 on switch one. 25 00:01:59,250 --> 00:02:09,330 So interface VLAN 11 IP address ten .1. 11 to 2 five four make sure that that SVI or switched virtual 26 00:02:09,330 --> 00:02:11,280 interfaces up which it is. 27 00:02:12,940 --> 00:02:13,620 So. 28 00:02:14,320 --> 00:02:15,520 Ken writer one ping. 29 00:02:15,520 --> 00:02:16,420 Writer three. 30 00:02:17,110 --> 00:02:18,370 It's just two artists. 31 00:02:18,370 --> 00:02:22,300 So paying ten one, 11, three. 32 00:02:24,270 --> 00:02:25,290 Yes, it can. 33 00:02:26,170 --> 00:02:29,710 Can it ping rather two rather two's using this IP address ten. 34 00:02:29,710 --> 00:02:30,700 One, two, two. 35 00:02:31,060 --> 00:02:32,020 Yes, it can. 36 00:02:32,470 --> 00:02:36,490 Can it ping Rutter for acting as PC two? 37 00:02:37,720 --> 00:02:39,910 So that's 2.4. 38 00:02:43,730 --> 00:02:45,110 Let's just do some troubleshooting. 39 00:02:45,110 --> 00:02:46,790 So first thing to confirm is. 40 00:02:48,410 --> 00:02:49,820 Let's check the interface. 41 00:02:52,640 --> 00:02:54,170 But interface looks right. 42 00:02:56,130 --> 00:02:58,440 Let's ping 11.1. 43 00:02:59,480 --> 00:03:01,600 Why is the ping not working? 44 00:03:01,610 --> 00:03:08,240 It's probably because I haven't set up a default gateway on router for let's confirm that show IP route. 45 00:03:09,280 --> 00:03:09,490 Yeah. 46 00:03:09,520 --> 00:03:12,250 No default is configured, so I'll turn off IP routing. 47 00:03:15,870 --> 00:03:20,820 Before I configure the default gateway, let me show you a test that we can do to prove what's happening. 48 00:03:21,540 --> 00:03:24,030 So another one I'm paying right for. 49 00:03:24,300 --> 00:03:31,050 And this debug debug IP ICMP shows us that the traffic hits root of four but is not getting back. 50 00:03:31,050 --> 00:03:36,780 So we can see that the traffic traverses, the network gets here but doesn't get back again. 51 00:03:37,170 --> 00:03:41,670 And that allows me to see that it's because my default gateway is not configured. 52 00:03:42,000 --> 00:03:49,320 So IP default gateway 10 to 1 .2.254 on router four because it's in VLAN two. 53 00:03:49,560 --> 00:03:53,310 So once again, this device is in VLAN 11. 54 00:03:54,690 --> 00:03:56,940 This device is in VLAN 11. 55 00:03:57,300 --> 00:03:59,490 These two devices on vlan two. 56 00:04:00,090 --> 00:04:02,460 So can write a one ping route of four. 57 00:04:02,490 --> 00:04:03,480 Yes it can. 58 00:04:04,150 --> 00:04:08,560 So let's have a look at the editor one Q Frames sent. 59 00:04:10,540 --> 00:04:13,300 He has rather one pinging out of four. 60 00:04:13,660 --> 00:04:15,700 And let's look at the ICMP. 61 00:04:19,010 --> 00:04:27,470 Now what you'll notice is the messages from ten one, 11 1 to 10 1 to 1 are actually being sent on VLAN 62 00:04:27,470 --> 00:04:31,640 two and the return traffic is being sent on VLAN two. 63 00:04:32,330 --> 00:04:39,470 And that's because the traffic is being sent from router one to switch one and switch one is already 64 00:04:39,470 --> 00:04:47,530 doing the inter VLAN routing and then forwarding the traffic to switch two on VLAN two. 65 00:04:47,540 --> 00:04:51,260 So it's already changing the VLAN information. 66 00:04:51,950 --> 00:04:55,640 To be VLAN two when forwarding it to the other switch. 67 00:04:57,140 --> 00:05:04,220 When the traffic goes from route of four to Ryder one, the traffic gets sent here as an untagged frame 68 00:05:04,220 --> 00:05:07,490 and then here it's tagged as VLAN two. 69 00:05:07,520 --> 00:05:12,620 When it hits the switch, which is acting as the default gateway, it does the interval and routing 70 00:05:12,620 --> 00:05:19,220 and then forwards it out of this port because it's in VLAN 11 and the traffic is going to a device in 71 00:05:19,220 --> 00:05:20,210 VLAN 11. 72 00:05:20,810 --> 00:05:31,250 So hence here we don't actually see the tagged frames, but we can see that by adding a router on a 73 00:05:31,250 --> 00:05:33,770 stick to do the interview LAN routing. 74 00:05:34,280 --> 00:05:40,730 So what I'll do is remove the interval and routing on switch one and configure this device as the routing 75 00:05:40,730 --> 00:05:43,100 device in the topology. 76 00:05:43,640 --> 00:05:46,370 And then what we should see is we should see. 77 00:05:48,020 --> 00:05:52,910 The tagged frames hit this router and then the tagging will be changed.