1 00:00:00,820 --> 00:00:02,650 So let's look at that practically. 2 00:00:02,690 --> 00:00:07,600 Yeah, I've got to switch one, switch two and switch three, switch two and switch three are connected 3 00:00:07,600 --> 00:00:08,440 to a hub. 4 00:00:09,260 --> 00:00:14,300 So that's following the topology shown in this Cisco guide. 5 00:00:14,810 --> 00:00:19,880 I've just booted up the switches, so you can see they're coming up at the moment. 6 00:00:21,270 --> 00:00:24,750 So these are brand new switches with no configuration at all. 7 00:00:28,050 --> 00:00:28,320 Okay. 8 00:00:28,320 --> 00:00:31,710 So on switch one, I'll set the host name to switch one. 9 00:00:33,330 --> 00:00:37,050 Switch to, I'll set the host name to switch to. 10 00:00:37,410 --> 00:00:38,820 You may be able to hear that. 11 00:00:38,820 --> 00:00:39,930 My CPU. 12 00:00:41,020 --> 00:00:44,400 He's maxed out while the switches are booting up. 13 00:00:45,310 --> 00:00:46,840 So at the moment my gene is three. 14 00:00:46,840 --> 00:00:50,530 VMM is at 87%, local CPU 62%. 15 00:00:50,710 --> 00:00:54,190 But that'll settle down in a moment, which it now has. 16 00:00:55,270 --> 00:00:59,020 So show shows. 17 00:01:00,800 --> 00:01:01,910 Spanning tree. 18 00:01:01,910 --> 00:01:03,410 So show spanning tree. 19 00:01:04,720 --> 00:01:06,910 At the moment, the switch is not to the root. 20 00:01:06,940 --> 00:01:11,620 You can see it's got a path cost to get to the route on gigabit zero one. 21 00:01:11,620 --> 00:01:19,030 So I'm assuming that switch three is the route show show spanning tree. 22 00:01:19,630 --> 00:01:25,780 We can see in the output here that switch three is the route switch of the topology. 23 00:01:25,900 --> 00:01:27,370 So I'll change that. 24 00:01:27,850 --> 00:01:34,810 I'm going to go onto switch one and top spending tree vlan one route. 25 00:01:35,800 --> 00:01:37,630 And actually I'll just set it by priority. 26 00:01:37,630 --> 00:01:40,330 So priority and let's set it to zero. 27 00:01:41,120 --> 00:01:43,760 So show spanning tree. 28 00:01:44,700 --> 00:01:51,390 We can see that the switch is now the root of the spanning tree for VLAN one. 29 00:01:51,900 --> 00:01:55,350 We are running rapid pivot on the switch. 30 00:01:55,890 --> 00:02:00,450 So some ports are still in the learning state. 31 00:02:02,630 --> 00:02:07,910 But then they go to forwarding so we can see all ports on the switch are forwarding. 32 00:02:08,150 --> 00:02:10,699 Those are the two ports of interest on switch one. 33 00:02:14,020 --> 00:02:16,210 On switch to shows spanning tree. 34 00:02:18,840 --> 00:02:20,850 So there's the come on show spending tree. 35 00:02:20,850 --> 00:02:22,860 We're running rapid spending tree. 36 00:02:24,700 --> 00:02:29,800 Podcast to get to the root is for out of Port one, which is gigabit zero zero. 37 00:02:31,260 --> 00:02:33,750 Gigabit zero zero is the root port. 38 00:02:34,840 --> 00:02:40,220 And notice how GIGABYTE zero one is the alternate port on the switch. 39 00:02:40,240 --> 00:02:41,980 It's in the blocking state. 40 00:02:42,550 --> 00:02:45,130 That's what we learnt in the Cisco document. 41 00:02:45,430 --> 00:02:52,720 An alternate port on the switch means that there is a port on another switch that's the designated port. 42 00:02:52,960 --> 00:02:57,010 In other words, it has a better path to get to the root bridge. 43 00:02:57,400 --> 00:02:59,020 So let's look at switch three. 44 00:02:59,940 --> 00:03:03,090 Show spanning tree on switch three. 45 00:03:03,330 --> 00:03:08,250 It has a part cost of fall out of Port one, which is gigabit zero zero. 46 00:03:08,250 --> 00:03:10,920 So this is the route port of switch three. 47 00:03:11,640 --> 00:03:15,480 We can see that here once again, gigabit zero zero is the route put. 48 00:03:16,310 --> 00:03:17,450 Into this output. 49 00:03:17,450 --> 00:03:25,190 Gigabit zero one is the designated port and gigabit zero two is the back up port. 50 00:03:25,730 --> 00:03:28,700 Back up port is in the blocking state. 51 00:03:29,120 --> 00:03:32,840 Alternate port on switch two is in the blocking state. 52 00:03:33,170 --> 00:03:34,970 So this port is blocking. 53 00:03:35,300 --> 00:03:36,830 This port is blocking. 54 00:03:36,860 --> 00:03:42,740 This is the only port that is forwarding on this segment connected to the hub. 55 00:03:42,920 --> 00:03:47,420 So loops will be blocked in this topology even though we connect it to a hub. 56 00:03:48,170 --> 00:03:53,990 That demonstrates the port roles and status that you get in rapid spanning tree on switch to once again 57 00:03:53,990 --> 00:03:55,400 I'll just move this up a bit. 58 00:03:57,420 --> 00:03:59,160 So on switch to. 59 00:04:01,290 --> 00:04:04,080 Connected to the hub on gigabit. 60 00:04:04,140 --> 00:04:05,220 Zero one. 61 00:04:06,650 --> 00:04:09,620 Gigabit S01 is an alternate port. 62 00:04:09,800 --> 00:04:11,210 That is the roll. 63 00:04:11,240 --> 00:04:14,270 The status of the port is blocking. 64 00:04:14,960 --> 00:04:16,730 Gigabit is zero zero. 65 00:04:16,940 --> 00:04:20,209 On that switch is a route port. 66 00:04:20,209 --> 00:04:25,370 That is the role and the status is forwarding on switch three. 67 00:04:26,860 --> 00:04:27,320 Gigabit. 68 00:04:27,370 --> 00:04:28,330 Zero zero. 69 00:04:28,360 --> 00:04:30,700 This port is the root port. 70 00:04:30,970 --> 00:04:33,010 It has a status of forwarding. 71 00:04:33,130 --> 00:04:36,010 That's the best port to use to get to the root bridge. 72 00:04:36,580 --> 00:04:38,320 Gigabit is zero one. 73 00:04:38,350 --> 00:04:42,610 In other words, this connection is the designated port. 74 00:04:42,640 --> 00:04:44,020 The role is designated. 75 00:04:44,020 --> 00:04:46,840 The status is forwarding this interface. 76 00:04:46,870 --> 00:04:50,570 Gigabit zero two is a backup port. 77 00:04:50,590 --> 00:04:53,680 That is the role the status is blocking. 78 00:04:53,860 --> 00:05:03,430 So blocking or discarding to use the industry standard term is the state of alternate as well as backup 79 00:05:03,460 --> 00:05:04,210 ports. 80 00:05:04,540 --> 00:05:11,170 Route ports and designated ports have the forwarding status in a stable topology. 81 00:05:11,350 --> 00:05:16,180 A state of learning means that traffic is still being discarded on the port. 82 00:05:16,630 --> 00:05:18,070 So as an example. 83 00:05:20,490 --> 00:05:22,250 On Gigabit zero zero. 84 00:05:22,380 --> 00:05:24,300 I'll shut the port down. 85 00:05:26,040 --> 00:05:34,050 Shows spanning tree notice gigabit is everyone is now forwarding gigabit zero two is the alternate put 86 00:05:34,290 --> 00:05:35,400 in a blocking state. 87 00:05:38,990 --> 00:05:41,600 The support here is now the designated port. 88 00:05:41,900 --> 00:05:47,240 It's in the learning status, which will hopefully move to forwarding in a moment. 89 00:05:47,660 --> 00:05:48,740 And there you go. 90 00:05:48,830 --> 00:05:56,120 The reason why it took time to transition to the forwarding state is that this is a shared port, not 91 00:05:56,120 --> 00:05:59,130 a point to point port, point to point ports. 92 00:05:59,150 --> 00:06:02,110 Transition immediately to forwarding shared ports. 93 00:06:02,120 --> 00:06:06,680 Don't they have to go through the timers of learning and then forwarding? 94 00:06:06,680 --> 00:06:14,360 So scrolling up we saw a learning state and then it went to the forwarding state. 95 00:06:14,450 --> 00:06:19,010 That's because it's a shared port, which means a half duplex interface. 96 00:06:19,040 --> 00:06:20,900 In other words, you connect it to a hub. 97 00:06:21,230 --> 00:06:27,290 This port should be configured as a point to point link because it's a direct connection from one switch 98 00:06:27,290 --> 00:06:28,070 to another. 99 00:06:28,280 --> 00:06:33,080 So as an example, what we should be doing is on gigabit zero zero, we should type. 100 00:06:33,080 --> 00:06:36,050 Spanning tree link type. 101 00:06:36,780 --> 00:06:41,940 Point to point, and we want to do that on both sides. 102 00:06:42,510 --> 00:06:48,210 Typically in the real world, your switches would negotiate a point to point link if the duplex was 103 00:06:48,210 --> 00:06:49,080 set to full. 104 00:06:49,950 --> 00:06:52,290 We'll do something similar on switch three. 105 00:06:53,850 --> 00:06:57,540 Gigabit zero zero should be point to point and gigabit is zero. 106 00:06:57,540 --> 00:06:58,660 One should be point to point. 107 00:06:58,680 --> 00:07:00,930 In other words, this link is point to point. 108 00:07:00,930 --> 00:07:02,310 This link is point to point. 109 00:07:02,640 --> 00:07:05,460 So back on switch to shows spanning tree. 110 00:07:06,740 --> 00:07:10,790 Notice the port type is point to point which allows for quicker convergence. 111 00:07:11,630 --> 00:07:19,340 On switch one show spanning tree both gigabit zero zero and gigabit zero one or point to point lengths.