WEBVTT 1 00:00.000 --> 00:03.040 All right, let's jump into our challenge here. 2 00:03.040 --> 00:07.880 What we're given is a set of switches in this triangle topology gives us a loop 3 00:07.880 --> 00:08.240 , as well 4 00:08.240 --> 00:11.290 as some priority values that are going to be used to help us determine which 5 00:11.290 --> 00:11.800 switch is 6 00:11.800 --> 00:12.800 the root. 7 00:12.800 --> 00:17.230 The thing we have to keep in mind is that it's the lower value that wins, and 8 00:17.230 --> 00:17.680 so the 9 00:17.680 --> 00:22.860 lowest value that's listed here would be switch to, and as a result, it becomes 10 00:22.860 --> 00:23.200 the 11 00:23.200 --> 00:24.200 root bridge. 12 00:24.200 --> 00:28.120 Now, it says we're to identify the roles, so our designated ports, our root 13 00:28.120 --> 00:28.800 ports, our 14 00:28.800 --> 00:31.080 non-designated ports. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 14 00:28.800 --> 00:31.080 non-designated ports. 15 00:31.080 --> 00:36.280 So what we're going to do is we're going to realize or remember that a root 16 00:36.280 --> 00:37.120 bridge has 17 00:37.120 --> 00:41.390 only designated ports, and those designated ports probably are going to connect 18 00:41.390 --> 00:41.840 to root 19 00:41.840 --> 00:42.840 ports. 20 00:42.840 --> 00:46.530 In fact, if all of these links are created equal, which they are, as called out 21 00:46.530 --> 00:46.800 in the 22 00:46.800 --> 00:50.200 lab, then this is always going to be the case. 23 00:50.200 --> 00:55.400 So we have designated port on the root connecting to a root port downstream. 24 00:55.400 --> 01:02.010 Remember, downstream this way, and then upstream is going to be viewed from the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 24 00:55.400 --> 01:02.010 Remember, downstream this way, and then upstream is going to be viewed from the 25 01:02.010 --> 01:03.680 other switches. 26 01:03.680 --> 01:08.200 So traffic flows this way, and we can follow the flow of BPDUs in this regard. 27 01:08.200 --> 01:11.690 So lastly, this is where we get into a situation, we're going to have to figure 28 01:11.690 --> 01:12.360 out which port 29 01:12.360 --> 01:16.130 to block, because both of these switches are going to send BPDUs to one another 30 01:16.130 --> 01:16.880 , expecting 31 01:16.880 --> 01:18.800 the other side to block. 32 01:18.800 --> 01:22.410 And at this point, we're not given enough information to know which side is 33 01:22.410 --> 01:22.920 going to 34 01:22.920 --> 01:23.920 block. 35 01:23.920 --> 01:28.040 And that's just because we haven't walked through the cost structure and how 36 01:28.040 --> 01:28.560 exactly 37 01:28.560 --> 01:30.720 these decisions are made yet. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 37 01:28.560 --> 01:30.720 these decisions are made yet. 38 01:30.720 --> 01:34.770 And the primary takeaway from this conversation is therefore, I just need to 39 01:34.770 --> 01:35.720 recognize which 40 01:35.720 --> 01:39.960 one of these ports, or which ones, are eligible. 41 01:39.960 --> 01:41.680 So either of these are eligible. 42 01:41.680 --> 01:43.760 One of them is going to be a designated port. 43 01:43.760 --> 01:45.440 Let's just say switch one. 44 01:45.440 --> 01:49.280 And one of them is going to be a non-designated port or a blocking port, which 45 01:49.280 --> 01:50.280 is switch three. 46 01:50.280 --> 01:54.480 So identify which ports are forwarding and which are blocking. 47 01:54.480 --> 02:01.390 Well, all of them are going to be in a forwarding state, as long as traffic is WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 47 01:54.480 --> 02:01.390 Well, all of them are going to be in a forwarding state, as long as traffic is 48 02:01.390 --> 02:02.720 going across 49 02:02.720 --> 02:04.080 the port. 50 02:04.080 --> 02:10.520 The one exception, except, are non-designated port. 51 02:10.520 --> 02:12.880 And so that would be this one right here. 52 02:12.880 --> 02:15.880 This is going to be in the blocking state. 53 02:15.880 --> 02:20.090 And so that's going to prevent the loop, which means we have an active link 54 02:20.090 --> 02:21.240 here and an active 55 02:21.240 --> 02:22.240 link here. 56 02:22.240 --> 02:23.840 And that would be our loop free topology. 57 02:23.840 --> 02:26.790 We're not going to use that link, even though, keep in mind that switch one 58 02:26.790 --> 02:27.760 continues to send 59 02:27.760 --> 02:33.440 BPDs and broadcast and flooded traffic for that matter down that link. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 59 02:27.760 --> 02:33.440 BPDs and broadcast and flooded traffic for that matter down that link. 60 02:33.440 --> 02:38.990 Now lastly, if a new switch is added into the topology here, what is the 61 02:38.990 --> 02:40.240 initial state 62 02:40.240 --> 02:42.160 of the port and what's the final state? 63 02:42.160 --> 02:47.160 So remember our order, we're going to start off in the listening state. 64 02:47.160 --> 02:49.120 And so that's the answer to the first question. 65 02:49.120 --> 02:52.130 Then we're going to go to the learning state, which is in the middle, and then 66 02:52.130 --> 02:52.600 we'll end 67 02:52.600 --> 02:57.100 up on forwarding because by connecting this with a single connection, there's 68 02:57.100 --> 02:57.760 no way for 69 02:57.760 --> 02:58.760 that to be a loop. 70 02:58.760 --> 03:01.920 And therefore, it will end up in the forwarding state. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 70 02:58.760 --> 03:01.920 And therefore, it will end up in the forwarding state. 71 03:01.920 --> 03:05.640 So there's still a lot to explore as far as how decisions like which port are 72 03:05.640 --> 03:06.080 we going 73 03:06.080 --> 03:09.540 to block those decisions have to be made and we have to understand how those 74 03:09.540 --> 03:10.120 decisions 75 03:10.120 --> 03:11.120 are made. 76 03:11.120 --> 03:14.260 At this point in the conversation, we should understand how the route bridge is 77 03:14.260 --> 03:14.920 selected, 78 03:14.920 --> 03:20.440 what the different route or port roles are, and how those look relative to the 79 03:20.440 --> 03:21.120 route, 80 03:21.120 --> 03:24.870 and then also what the different port states are, and especially understand 81 03:24.870 --> 03:25.600 what the port 82 03:25.600 --> 03:29.000 state transition looks like when we bring a port online. 83 03:29.000 --> 03:31.640 I hope there's been informative for you and I'd like to thank you for viewing. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 83 03:29.000 --> 03:31.640 I hope there's been informative for you and I'd like to thank you for viewing.