WEBVTT 1 00:00.000 --> 00:04.610 Well, an important part of understanding a technology is knowing how to 2 00:04.610 --> 00:05.880 configure it. 3 00:05.880 --> 00:09.040 And so that's exactly what this lab exercise is designed to do. 4 00:09.040 --> 00:13.310 If you haven't yet done so, please feel free to hit the pause button, go back 5 00:13.310 --> 00:13.880 and do the 6 00:13.880 --> 00:14.880 lab above. 7 00:14.880 --> 00:17.860 And if you already did it and you just want to check your answers, then check 8 00:17.860 --> 00:18.320 out the 9 00:18.320 --> 00:19.880 solution script below. 10 00:19.880 --> 00:24.180 If you've got everything right, you feel confident about it, then by all means, 11 00:24.180 --> 00:24.720 confirm 12 00:24.720 --> 00:27.400 that you have the right solution and then move on. 13 00:27.400 --> 00:30.550 If any of these tripped you up or you want to know the explanation behind it, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 13 00:27.400 --> 00:30.550 If any of these tripped you up or you want to know the explanation behind it, 14 00:30.550 --> 00:30.960 then feel 15 00:30.960 --> 00:34.760 free to watch this video as we'll go through all of the solutions together. 16 00:34.760 --> 00:38.810 So first up, we simply need to enable rapid pervieland spanning tree in the 17 00:38.810 --> 00:39.760 environment. 18 00:39.760 --> 00:42.440 So I'm going to be doing this on switches three, four and five. 19 00:42.440 --> 00:47.580 I'm going to do a config T and that is simply typing in spanning tree mode and 20 00:47.580 --> 00:48.360 then rapid 21 00:48.360 --> 00:50.360 pvst. 22 00:50.360 --> 00:54.800 And so I'm going to go ahead and do that on switches four and five as well. 23 00:54.800 --> 01:00.170 Spanning tree mode rapid, we can abbreviate it if we want to be a little faster WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 23 00:54.800 --> 01:00.170 Spanning tree mode rapid, we can abbreviate it if we want to be a little faster 24 01:00.170 --> 01:00.720 and spanning 25 01:00.720 --> 01:02.560 tree mode rapid. 26 01:02.560 --> 01:07.560 And the way I can confirm that it's working is if I do a show spanning tree. 27 01:07.560 --> 01:11.770 And then I see that it says protocol RSTP as opposed to protocol IEEE, which 28 01:11.770 --> 01:12.640 would indicate 29 01:12.640 --> 01:16.320 that we are running the legacy 802.1d. 30 01:16.320 --> 01:18.620 Now we're also going to find that we have an instance per VLAN because we're 31 01:18.620 --> 01:19.000 running 32 01:19.000 --> 01:21.200 rapid pvst and not MST. 33 01:21.200 --> 01:25.320 And it's perfectly fine. That's what this lab is expecting us to do. 34 01:25.320 --> 01:29.320 Now next we want to configure switch three as the route for the odd VLANs and 35 01:29.320 --> 01:30.040 switch for WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 35 01:29.320 --> 01:30.040 switch for 36 01:30.040 --> 01:31.240 the route for the events. 37 01:31.240 --> 01:35.280 This is going to take a little bit of configuration on each side. 38 01:35.280 --> 01:39.000 It's not too bad, but I'm going to do one of two things here. 39 01:39.000 --> 01:43.280 So switch three odd VLANs, one, three, five, seven and nine. 40 01:43.280 --> 01:46.680 Since we're dealing with VLANs one through ten, it's just those five VLANs. 41 01:46.680 --> 01:50.900 And then I can either configure this with root primary or I could do something 42 01:50.900 --> 01:51.440 along the 43 01:51.440 --> 01:56.680 lines of priority 40, 96, something along those lines. 44 01:56.680 --> 02:02.230 So I can do that for the backup or I can configure it as a backup for the even WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 44 01:56.680 --> 02:02.230 So I can do that for the backup or I can configure it as a backup for the even 45 02:02.230 --> 02:02.800 VLANs 46 02:02.800 --> 02:08.640 as well by configuring it with something that's between 4K and the default 32K. 47 02:08.640 --> 02:11.720 And so that's exactly what I'll do for switch three. 48 02:11.720 --> 02:14.160 And then on switch four, I'm going to do the opposite. 49 02:14.160 --> 02:19.990 I'm going to say spanning tree VLANs one, three, five, seven, nine, priority 81 50 02:19.990 --> 02:20.680 , 92. 51 02:20.680 --> 02:24.080 So a worse priority, but again, this is going to be the backup for the odds. 52 02:24.080 --> 02:29.050 It's going to be the primary for the events two, four, six, eight and ten, 53 02:29.050 --> 02:30.280 priority 40, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 53 02:29.050 --> 02:30.280 priority 40, 54 02:30.280 --> 02:31.600 96. 55 02:31.600 --> 02:36.380 So now I should do a show spanning tree root just to confirm that everything is 56 02:36.380 --> 02:37.160 working. 57 02:37.160 --> 02:40.760 I should see every other one of these has a root port, meaning that it's not 58 02:40.760 --> 02:41.240 the root 59 02:41.240 --> 02:45.280 because I have a path to the root, but then if I don't have a root port, that 60 02:45.280 --> 02:45.600 means that 61 02:45.600 --> 02:48.360 I am the root because I don't need a path to the root. 62 02:48.360 --> 02:50.440 So we see it alternating here. 63 02:50.440 --> 02:55.560 If I go back to switch three, show spanning tree root, I should see the same 64 02:55.560 --> 02:56.040 thing and 65 02:56.040 --> 02:57.040 indeed I do. 66 02:57.040 --> 02:59.400 So everything is looking pretty good so far. 67 02:59.400 --> 03:03.240 So next up, we need to configure port fast. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 67 02:59.400 --> 03:03.240 So next up, we need to configure port fast. 68 03:03.240 --> 03:09.180 So the goal here is to make it so that a couple of access ports on switch five 69 03:09.180 --> 03:09.520 are going 70 03:09.520 --> 03:12.360 to not send TCN. 71 03:12.360 --> 03:17.790 So if I do a show IP and brief, we're going to see a lot of ports in an 72 03:17.790 --> 03:19.520 administratively 73 03:19.520 --> 03:24.770 town status, but we do see gig two slash two here and two slash three should 74 03:24.770 --> 03:25.680 actually be 75 03:25.680 --> 03:27.200 online as well. 76 03:27.200 --> 03:32.440 But either way, it's in a show run interface gig two slash two. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 76 03:27.200 --> 03:32.440 But either way, it's in a show run interface gig two slash two. 77 03:32.440 --> 03:33.760 There we go. 78 03:33.760 --> 03:34.760 Switch mode access. 79 03:34.760 --> 03:37.920 So we want to make sure that this is running in port fast operation. 80 03:37.920 --> 03:42.960 If I do a show spanning tree interface and then add detail to the end, this is 81 03:42.960 --> 03:43.600 as we've 82 03:43.600 --> 03:48.160 seen several times, a really great way to see how a port is configured from an 83 03:48.160 --> 03:49.240 STP perspective. 84 03:49.240 --> 03:51.480 I don't see anything down here other than that. 85 03:51.480 --> 03:54.040 It's in point to point, which is good for rapid spanning tree. 86 03:54.040 --> 03:57.510 It means we can negotiate with a device out there, but nothing here about it 87 03:57.510 --> 03:58.040 being an 88 03:58.040 --> 03:59.520 edge port. 89 03:59.520 --> 04:04.570 Now I'm explicitly told that we want to make sure that not only these ports, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 89 03:59.520 --> 04:04.570 Now I'm explicitly told that we want to make sure that not only these ports, 90 04:04.570 --> 04:05.320 but also 91 04:05.320 --> 04:10.910 all future ports become immune to sending TCNs, at least from an edge 92 04:10.910 --> 04:12.360 perspective. 93 04:12.360 --> 04:15.920 And so I can accomplish this by configuring it globally. 94 04:15.920 --> 04:19.080 So I can do the spanning tree port fast. 95 04:19.080 --> 04:21.400 And again, some platforms require this edge command. 96 04:21.400 --> 04:22.400 Some do not. 97 04:22.400 --> 04:25.520 So be aware of that, especially the virtual switches do. 98 04:25.520 --> 04:28.080 And then I can simply say default here. 99 04:28.080 --> 04:33.480 And this is going to apply edge configuration by default to all access WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 99 04:28.080 --> 04:33.480 And this is going to apply edge configuration by default to all access 100 04:33.480 --> 04:34.800 interfaces. 101 04:34.800 --> 04:37.640 So again, I do that show spanning tree interface. 102 04:37.640 --> 04:41.040 I pick gig two slash two detail. 103 04:41.040 --> 04:45.670 And we see that now it says that it's not only in port fast edge mode, it also 104 04:45.670 --> 04:46.240 says that 105 04:46.240 --> 04:49.240 it's by default because I configured it globally. 106 04:49.240 --> 04:52.080 So that's exactly what we were looking for that will apply not only to the 107 04:52.080 --> 04:53.000 existing access 108 04:53.000 --> 04:57.640 ports, but also to all future ports as well. 109 04:57.640 --> 05:01.760 So now we need to configure, well, all the protection mechanisms. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 109 04:57.640 --> 05:01.760 So now we need to configure, well, all the protection mechanisms. 110 05:01.760 --> 05:03.520 This is where it gets a little bit fun. 111 05:03.520 --> 05:08.370 So we're told that we need to protect our roots from any other device claiming 112 05:08.370 --> 05:08.760 to be 113 05:08.760 --> 05:09.760 the root. 114 05:09.760 --> 05:13.260 And we can also test this, but we're going to get on to switch three and switch 115 05:13.260 --> 05:13.600 four 116 05:13.600 --> 05:17.840 and identify the downstream facing ports. 117 05:17.840 --> 05:21.320 And in our case, that's going to be gig two slash one on switch three here. 118 05:21.320 --> 05:25.680 So config T interface gig two slash one. 119 05:25.680 --> 05:29.880 And then I'm going to enter spanning tree guard root. 120 05:29.880 --> 05:33.480 And that will enable root guard on the downstream port. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 120 05:29.880 --> 05:33.480 And that will enable root guard on the downstream port. 121 05:33.480 --> 05:38.360 On switch four, that's going to be interface gig three slash one. 122 05:38.360 --> 05:41.800 And again, spanning tree guard root. 123 05:41.800 --> 05:46.000 So now these switches will protect themselves against superior BPD use. 124 05:46.000 --> 05:49.250 Notice like we talked about in the quiz, we do not want to enable this between 125 05:49.250 --> 05:49.760 switches 126 05:49.760 --> 05:51.280 three and four. 127 05:51.280 --> 05:52.600 And so let's go ahead and test this. 128 05:52.600 --> 05:56.950 I'm going to get on to switch five and say, let's just pick a VLAN here 129 05:56.950 --> 05:58.160 spanning tree V 130 05:58.160 --> 06:00.920 land five and then priority of zero. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 130 05:58.160 --> 06:00.920 land five and then priority of zero. 131 06:00.920 --> 06:04.080 So it's claiming to be the root for VLAN five. 132 06:04.080 --> 06:06.960 I come take a look at this. 133 06:06.960 --> 06:07.960 And we're all wrong. 134 06:07.960 --> 06:09.120 I was waiting for a new log message. 135 06:09.120 --> 06:10.120 It's already there. 136 06:10.120 --> 06:13.440 Root guard is already blocking that port for VLAN five. 137 06:13.440 --> 06:17.760 So what's interesting about this is it does operate independent of, well, it 138 06:17.760 --> 06:18.400 operates 139 06:18.400 --> 06:20.240 on a per VLAN basis, I should say. 140 06:20.240 --> 06:24.860 So if I do a show spanning tree, for example, I'm VLAN one, everything looks 141 06:24.860 --> 06:25.680 fine on VLAN 142 06:25.680 --> 06:27.960 two, everything is going to look fine. 143 06:27.960 --> 06:32.580 But if I go past three and four and I look at VLAN five, this is where we're WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 143 06:27.960 --> 06:32.580 But if I go past three and four and I look at VLAN five, this is where we're 144 06:32.580 --> 06:33.080 going to 145 06:33.080 --> 06:37.960 see that broken status because it's in the STP inconsistent and specifically 146 06:37.960 --> 06:38.560 the root 147 06:38.560 --> 06:40.560 inconsistent state. 148 06:40.560 --> 06:42.040 So we're protecting ourselves. 149 06:42.040 --> 06:44.000 We are still the root. 150 06:44.000 --> 06:46.880 This bridge remains the root for VLAN five. 151 06:46.880 --> 06:48.800 That's exactly what we want to see. 152 06:48.800 --> 06:51.080 And we've proven that our root guard configuration works. 153 06:51.080 --> 06:55.440 Let's just go ahead and reset this back to the default of 3,278. 154 06:55.440 --> 06:56.680 And everything will come back up. 155 06:56.680 --> 07:00.340 That's one nice thing about this inconsistent state is once the status is WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 155 06:56.680 --> 07:00.340 That's one nice thing about this inconsistent state is once the status is 156 07:00.340 --> 07:01.280 restored, there 157 07:01.280 --> 07:02.280 we go. 158 07:02.280 --> 07:03.800 We are unblocking that port. 159 07:03.800 --> 07:05.520 Everything is going to be happy. 160 07:05.520 --> 07:07.080 VLAN five. 161 07:07.080 --> 07:10.320 And we see we're already back up and online. 162 07:10.320 --> 07:12.670 As since we're rapid spanning true, we didn't have to wait for listening and 163 07:12.670 --> 07:13.160 learning, which 164 07:13.160 --> 07:14.840 is really nice. 165 07:14.840 --> 07:16.240 So that's root guard. 166 07:16.240 --> 07:17.720 Next up is BPDU guard. 167 07:17.720 --> 07:21.420 We're told that back to switch five, our access layer switch, we want to make 168 07:21.420 --> 07:23.160 sure that all 169 07:23.160 --> 07:28.010 of our access ports block any incoming BPDUs because that's where BPDUs should 170 07:28.010 --> 07:28.320 never 171 07:28.320 --> 07:29.720 arrive. 172 07:29.720 --> 07:34.160 But once again, I have to enable this for all future access ports as well. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 172 07:29.720 --> 07:34.160 But once again, I have to enable this for all future access ports as well. 173 07:34.160 --> 07:38.720 So there's another command that we can run globally that will allow for this, 174 07:38.720 --> 07:39.160 but it 175 07:39.160 --> 07:46.400 does require us, keep in mind, to map this to BPDU or to portfast ports. 176 07:46.400 --> 07:47.400 So it's interesting. 177 07:47.400 --> 07:50.200 Portfast globally maps to access ports. 178 07:50.200 --> 07:52.360 BPDU guard maps to portfast. 179 07:52.360 --> 07:55.360 So we already configured portfast to map to all the access ports. 180 07:55.360 --> 08:00.040 Now we have to configure BPDU guard to map to the portfast ports. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 180 07:55.360 --> 08:00.040 Now we have to configure BPDU guard to map to the portfast ports. 181 08:00.040 --> 08:04.270 So I'm going to use this global command, spanning tree portfast, again, edge is 182 08:04.270 --> 08:05.320 sometimes required 183 08:05.320 --> 08:06.320 here. 184 08:06.320 --> 08:09.320 And then we're going to, that's the wrong command. 185 08:09.320 --> 08:13.080 We're going to question mark, we see BPDU guard is there. 186 08:13.080 --> 08:16.280 So now I can say BPDU guard. 187 08:16.280 --> 08:19.680 And then we should just be able to say default. 188 08:19.680 --> 08:20.680 Yes. 189 08:20.680 --> 08:25.860 So once again, if I want to confirm this, I can do a show interface, no, so 190 08:25.860 --> 08:26.600 spanning 191 08:26.600 --> 08:32.240 tree interface, and then take a look at that gig two slash two detailed. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 191 08:26.600 --> 08:32.240 tree interface, and then take a look at that gig two slash two detailed. 192 08:32.240 --> 08:35.840 And we should see that BPDU guard is also enabled by default now. 193 08:35.840 --> 08:38.200 So I want to make sure both of these are listed here. 194 08:38.200 --> 08:41.880 If only one is listed or neither is listed, then that means there's a problem 195 08:41.880 --> 08:42.400 with one 196 08:42.400 --> 08:43.400 of our configurations. 197 08:43.400 --> 08:48.400 Either this port's not in an access port or something else broken our process. 198 08:48.400 --> 08:52.940 But this command is really wonderful for confirming that all of the 199 08:52.940 --> 08:54.200 configurations that we put 200 08:54.200 --> 08:57.800 into place are actually being used. 201 08:57.800 --> 09:01.400 So next up, we want to configure switch five to block any port that stops WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 201 08:57.800 --> 09:01.400 So next up, we want to configure switch five to block any port that stops 202 09:01.400 --> 09:03.480 receiving BPDUs. 203 09:03.480 --> 09:06.860 So at that point, we're talking about spanning tree loop guard because the 204 09:06.860 --> 09:07.560 focus is on not 205 09:07.560 --> 09:12.250 receiving BPDUs, we are going to configure this within the spanning tree world 206 09:12.250 --> 09:12.720 rather 207 09:12.720 --> 09:15.400 than rely on UDLD specifically. 208 09:15.400 --> 09:20.960 Now, once again, we can configure things globally or on a per port basis. 209 09:20.960 --> 09:25.420 And so instead of doing this on a per interface basis, I'm just going to 210 09:25.420 --> 09:27.200 configure this globally. 211 09:27.200 --> 09:32.280 And so the global command for this is simply spanning tree loop guard default, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 211 09:27.200 --> 09:32.280 And so the global command for this is simply spanning tree loop guard default, 212 09:32.280 --> 09:32.920 which is 213 09:32.920 --> 09:36.760 interesting because I get if I get on an interface, it uses guard loop. 214 09:36.760 --> 09:37.760 So keep that in mind. 215 09:37.760 --> 09:42.410 I get onto interface gig two slash two and say spanning tree loop guard doesn't 216 09:42.410 --> 09:42.800 show 217 09:42.800 --> 09:45.800 up here, instead I have to do guard question mark. 218 09:45.800 --> 09:47.040 And then I see loop. 219 09:47.040 --> 09:48.640 So the syntax is a little bit different. 220 09:48.640 --> 09:51.600 If we're on an interface, just keep that in mind. 221 09:51.600 --> 09:55.340 We have to configure it on an interface specifically that the command might not 222 09:55.340 --> 09:56.520 be quite what we're 223 09:56.520 --> 09:57.520 expecting. 224 09:57.520 --> 10:02.160 But now again, I can do a show spanning tree interface gig. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 224 09:57.520 --> 10:02.160 But now again, I can do a show spanning tree interface gig. 225 10:02.160 --> 10:06.360 Well, just take a look at gig two slash two again detail. 226 10:06.360 --> 10:09.280 And we'll see that loop guard is now enabled by default. 227 10:09.280 --> 10:12.400 So again, I love this command, we use it all the time. 228 10:12.400 --> 10:17.400 And importantly, this is going to matter when I look at my upstream interface. 229 10:17.400 --> 10:19.160 And I did not do the detailed commands. 230 10:19.160 --> 10:21.560 Let's add that. 231 10:21.560 --> 10:25.460 And then when we're looking at this from a per VLAN perspective, because now 232 10:25.460 --> 10:25.920 again, this 233 10:25.920 --> 10:26.920 is a trunk. 234 10:26.920 --> 10:28.640 So it's running all 10 VLANs. 235 10:28.640 --> 10:31.880 When I look at one of these, notice I don't see port type edge. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 235 10:28.640 --> 10:31.880 When I look at one of these, notice I don't see port type edge. 236 10:31.880 --> 10:33.360 I don't see BPDU guard. 237 10:33.360 --> 10:34.360 That's good. 238 10:34.360 --> 10:36.440 But I do see loop guard is enabled. 239 10:36.440 --> 10:40.760 And so that's what we'd expect from our configuration up until now. 240 10:40.760 --> 10:45.460 Lastly, lastly, lastly, we have one more protection mechanism, which is going 241 10:45.460 --> 10:47.520 to amount to UDLD. 242 10:47.520 --> 10:51.000 It says configure all switches to shut down fiber ports current and future that 243 10:51.000 --> 10:51.400 become 244 10:51.400 --> 10:52.600 unidirectional. 245 10:52.600 --> 10:58.790 Well, UDLD works such that if I enable it globally, it will only enable fiber 246 10:58.790 --> 10:59.480 ports, 247 10:59.480 --> 11:03.960 but it will do it for all fiber ports globally, meaning that in the future, it WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 247 10:59.480 --> 11:03.960 but it will do it for all fiber ports globally, meaning that in the future, it 248 11:03.960 --> 11:04.800 'll shut down 249 11:04.800 --> 11:07.320 fiber ports, or I should say it like this. 250 11:07.320 --> 11:10.240 It'll activate UDLD on the fiber ports. 251 11:10.240 --> 11:13.960 Also, keep in mind, the UDLD must be enabled on both sides. 252 11:13.960 --> 11:17.250 Notice I only enabled loop guard on switch five, because it's from switch five 253 11:17.250 --> 11:18.080 's perspective. 254 11:18.080 --> 11:22.220 If I receive a BPDU and receive a BPDU and then it stops, that's from my 255 11:22.220 --> 11:23.120 perspective, 256 11:23.120 --> 11:24.120 not from yours. 257 11:24.120 --> 11:26.640 UDLD requires us to work together. 258 11:26.640 --> 11:29.920 So we have to enable this on all of our switches. 259 11:29.920 --> 11:34.490 We're going to do it globally to enable it on all the fiber ports, and then we WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 259 11:29.920 --> 11:34.490 We're going to do it globally to enable it on all the fiber ports, and then we 260 11:34.490 --> 11:35.080 also need 261 11:35.080 --> 11:37.600 to make sure that the port will be shut down. 262 11:37.600 --> 11:39.160 That means aggressive mode. 263 11:39.160 --> 11:43.250 So if I do UDLD question mark, we're going to see I can do a UDLD enable that 264 11:43.250 --> 11:43.640 enables 265 11:43.640 --> 11:48.000 normal mode, normal mode, or I can do aggressive. 266 11:48.000 --> 11:50.840 And that's exactly what we want, UDLD aggressive. 267 11:50.840 --> 11:55.640 But in order to make it work, we're going to have to go around to all of the 268 11:55.640 --> 11:57.480 other switches 269 11:57.480 --> 11:59.760 and make sure that they're configured for that as well. 270 11:59.760 --> 12:05.800 So switch five, switch four, switch three, UDLD aggressive. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 270 11:59.760 --> 12:05.800 So switch five, switch four, switch three, UDLD aggressive. 271 12:05.800 --> 12:09.880 So then we can run show UDLD neighbors command. 272 12:09.880 --> 12:15.350 And once we see that the communication starts to get established, then we will 273 12:15.350 --> 12:16.120 find that 274 12:16.120 --> 12:17.760 the neighbors start to get listed here. 275 12:17.760 --> 12:18.760 Now it's not coming up. 276 12:18.760 --> 12:20.400 Let's see here. 277 12:20.400 --> 12:22.640 Show UDLD neighbors. 278 12:22.640 --> 12:23.840 See if it's coming up over here. 279 12:23.840 --> 12:24.840 Oh, cool. 280 12:24.840 --> 12:25.840 It's not coming up on it. 281 12:25.840 --> 12:28.480 Oh, because we only enabled it on fiber boards. 282 12:28.480 --> 12:30.880 And this is a lab environment where it thinks everything is copper. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 282 12:28.480 --> 12:30.880 And this is a lab environment where it thinks everything is copper. 283 12:30.880 --> 12:33.400 So hey, that's exactly what we want from this output. 284 12:33.400 --> 12:36.550 Naturally, if we want to see these outputs, we can get on to the individual 285 12:36.550 --> 12:37.080 interfaces 286 12:37.080 --> 12:38.160 and configure it. 287 12:38.160 --> 12:41.060 But that's just a good reminder that, hey, this is only going to work on fiber 288 12:41.060 --> 12:41.320 ports 289 12:41.320 --> 12:43.080 if we enable it globally. 290 12:43.080 --> 12:46.380 So a great lab exercise to go through, make sure we number one know how to 291 12:46.380 --> 12:47.080 enable rapid 292 12:47.080 --> 12:48.360 spanning tree. 293 12:48.360 --> 12:53.200 Also very importantly, know how to enable all of these protection mechanisms. 294 12:53.200 --> 12:57.040 Because again, these are configurations that belong in production networks. 295 12:57.040 --> 13:00.800 For running rapid spanning tree, if we're running MST, it doesn't matter. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 295 12:57.040 --> 13:00.800 For running rapid spanning tree, if we're running MST, it doesn't matter. 296 13:00.800 --> 13:05.320 We should be deploying these technologies so that we can protect our network, 297 13:05.320 --> 13:05.600 not only 298 13:05.600 --> 13:09.600 from a topology perspective, but also from potential loops that could show up 299 13:09.600 --> 13:09.920 in ways 300 13:09.920 --> 13:11.800 that spanning tree doesn't protect us. 301 13:11.800 --> 13:13.280 I hope this has been informative for you. 302 13:13.280 --> 13:14.280 And I'd like to thank you for viewing.