1 00:00:16,920 --> 00:00:19,230 Okay, so let's complete this lab. 2 00:00:19,500 --> 00:00:24,310 The first step is to verify links using CDP and LLDP. 3 00:00:24,920 --> 00:00:25,890 So on core 1 4 00:00:30,160 --> 00:00:32,700 show CDP neighbors at the moment, 5 00:00:32,710 --> 00:00:41,520 we don't see any neighbors. Show IP interface brief, interfaces are up but no neighbors are displaying 6 00:00:43,420 --> 00:00:48,690 shows CDP, CDP is enabled on the switch. 7 00:00:48,690 --> 00:00:50,670 What about switch 2? 8 00:00:55,360 --> 00:00:56,550 Show CDP 9 00:00:56,560 --> 00:01:08,030 neighbors, notice the problem CDP is not enabled on switch 2. Now in the real world, CDP is enabled on 10 00:01:08,030 --> 00:01:17,850 Cisco devices by default. If it's not enabled use the command CDP run in global config mode. So shows CDP 11 00:01:17,850 --> 00:01:25,680 neighbors now shows us that we don't have any neighbors but we are seeing some output that's different 12 00:01:26,070 --> 00:01:28,580 to what we saw previously. 13 00:01:28,780 --> 00:01:39,460 So what I'll do initially is simply make sure that CDP is enabled on all devices, show CDP neighbors 14 00:01:39,990 --> 00:01:49,410 CDP is not enabled so CDP run. Do something similar on access 2. 15 00:01:53,070 --> 00:02:00,770 Show CDP neighbors not enabled so CDP run access 3 16 00:02:05,640 --> 00:02:12,420 before I enable it let's confirm not enabled CDP run. 17 00:02:12,460 --> 00:02:24,210 Okay, so back on core 1 show CDP neighbors notice we are now seeing our neighbors, so we can confirm that 18 00:02:24,210 --> 00:02:33,540 core 2 is connected to our local interfaces gigabit 1 0 23 and 1 0 24. Core 2 is using 19 00:02:33,870 --> 00:02:42,530 this port gigabit 1 0 23 to connect to our gigabit 1 0 23, core 2 is gigabit 1 0 20 00:02:42,530 --> 00:02:52,150 24 interface is connected to our gigabit 1 0 24 interface, that looks good. Access 1 is connected 21 00:02:52,150 --> 00:02:58,980 via gigabit 1 0 23 to our local interface gigabit 1 0 1. 22 00:02:59,230 --> 00:03:00,310 So that looks good. 23 00:03:01,920 --> 00:03:04,390 Access 2 gigabit 1 0 23 24 00:03:04,400 --> 00:03:12,740 this interface is connected to gigabit 1 0 2 also looks good access 3 gigabit 1 0 25 00:03:12,740 --> 00:03:21,020 23 is connected to our gigabit 1 0 3 interface so that also looks good. So the CDP output 26 00:03:21,110 --> 00:03:29,290 looks correct on core1 CDP doesn't run on servers so we don't see the server in the output. 27 00:03:29,660 --> 00:03:31,960 What about core 2? 28 00:03:32,030 --> 00:03:33,290 So in core 2 29 00:03:36,170 --> 00:03:41,390 show CDP neighbors core 1 looks correct, 30 00:03:41,580 --> 00:03:50,520 access 1 is using gigabit 1 0 24 to connect to our local 1 0 1 interface that looks good. 31 00:03:50,880 --> 00:03:59,270 Access 2 and 3 are doing something similar so that looks good what we aren't seeing here is the router. 32 00:03:59,960 --> 00:04:06,390 So let's check the router. 33 00:04:06,530 --> 00:04:17,610 Show CDP neighbor, CDP is not enabled so CDP run, show CDP neighbor now may take it a while. 34 00:04:17,610 --> 00:04:26,760 Just remember with CDP it sends updates out every 60 seconds so it could take up to 60 seconds for you 35 00:04:26,760 --> 00:04:28,980 to see a neighbor relationship. 36 00:04:28,980 --> 00:04:31,410 So you just need to be patient. 37 00:04:31,800 --> 00:04:39,420 Don't assume there's a problem if you don't see a neighbor immediately wait at least a minute and there 38 00:04:39,420 --> 00:04:43,690 you go we can see the router on core 2. 39 00:04:43,770 --> 00:04:47,740 We can see that it's a router, we can see that it's an ISR. 40 00:04:47,970 --> 00:04:56,770 We can also see that the other switches in the topology are 36 60s, back in the ISR may take it a while. 41 00:04:57,170 --> 00:05:06,840 So I'll come back to that on access 1 show CDP neighbor it's got 2 neighbor relationships, 1 to core 1 42 00:05:06,950 --> 00:05:08,360 1 to core 2. 43 00:05:08,440 --> 00:05:13,180 That looks good, now typically you don't have to do it both ways. 44 00:05:13,200 --> 00:05:18,690 If you see the neighbor relationship on one side you'll see it on the other side. 45 00:05:18,810 --> 00:05:20,340 That's not always true 46 00:05:20,340 --> 00:05:27,660 however when you have multi vendor environments HPE switches as an example will receive CDP messages 47 00:05:27,690 --> 00:05:28,850 but not send it. 48 00:05:29,490 --> 00:05:32,740 So you may wanna check things on both sides. 49 00:05:33,090 --> 00:05:40,440 But remember that when you have multiple vendors or if there's an access list blocking CDP coming in to a 50 00:05:40,460 --> 00:05:45,090 switch you may see it only on one side that looks good. 51 00:05:45,120 --> 00:05:51,380 So access 3 is seeing core 1 and 2 and again back on access 2 52 00:05:51,450 --> 00:05:56,280 we can see core 1 and core 2 so that CDP. 53 00:05:56,580 --> 00:05:58,320 But we're not finished yet 54 00:05:58,350 --> 00:06:00,930 we need to check LLDP.