1 00:00:00,840 --> 00:00:05,250 Now rapid spending tree is backward compatible with 82 to 1 D. 2 00:00:05,400 --> 00:00:11,730 And in the same way Rapid PvZ T is compatible with PvP on switch three. 3 00:00:11,760 --> 00:00:17,280 These ports were converging quickly because we're using rapid spanning tree between switch one, two 4 00:00:17,280 --> 00:00:21,660 and three, but the links to switch four are still using PVS. 5 00:00:21,660 --> 00:00:27,120 DT So what you'll notice is it takes longer for those lengths to converge. 6 00:00:29,990 --> 00:00:35,570 Show Spending Tree, as an example, shows me that the ports are now forwarding, but they've taken 7 00:00:35,570 --> 00:00:40,640 a lot longer to converge than they would with rapid pivot. 8 00:00:40,850 --> 00:00:47,870 So once again, on interface gigabit zero one, I'll know shut the port show spanning tree. 9 00:00:47,900 --> 00:00:54,710 We can already see that gigabit zero one is the root port and is forwarding and gigabit is zero zero 10 00:00:54,710 --> 00:00:57,050 is an alternate port and is blocking. 11 00:00:58,330 --> 00:01:04,569 However, other ports such as Gigabyte zero two and zero three are still learning. 12 00:01:04,870 --> 00:01:10,930 So it's going to take time for these ports to move to the forwarding state. 13 00:01:10,960 --> 00:01:15,760 You can see they've now moved to the forwarding state, but that's because there is an older version 14 00:01:15,760 --> 00:01:20,050 of spending tree negotiated between switch three and switch four. 15 00:01:20,230 --> 00:01:22,750 Switch three once again is using. 16 00:01:23,940 --> 00:01:27,540 Rapid pivot switch for, however. 17 00:01:31,940 --> 00:01:37,070 He's using per vlan spanning tree not rapid PV ist. 18 00:01:37,220 --> 00:01:44,270 So I triple e is shown in the output whereas once again on switch three it's rapid PV ist, so there 19 00:01:44,270 --> 00:01:52,040 is backward compatibility between rapid PV ist and PV ist, but the convergence will be slow between 20 00:01:52,040 --> 00:01:58,310 rapid PV ist and PV ist because of backward compatibility and within the PV ist part of your network. 21 00:01:59,280 --> 00:02:01,320 Let's have a look at the capture. 22 00:02:03,440 --> 00:02:07,250 So this is on switch three as advertised to the hub. 23 00:02:07,910 --> 00:02:14,480 And what you can see here is that the protocol used is spanning tree, not rapid, spanning tree. 24 00:02:15,350 --> 00:02:21,650 And that's because switch three has negotiated to use spanning tree with switch for not rapid spanning 25 00:02:21,680 --> 00:02:22,220 tree. 26 00:02:22,460 --> 00:02:27,800 So in the output once again it's spanning tree protocol not rapid spanning tree protocol. 27 00:02:28,280 --> 00:02:29,290 Path cost. 28 00:02:29,610 --> 00:02:35,750 Root identify and bridge identify are shown here, but it's negotiated to use the older version of Spanning 29 00:02:35,780 --> 00:02:36,230 Tree. 30 00:02:36,770 --> 00:02:43,160 Even though this document is old, it provides a great explanation of rapid spanning tree or ADA two 31 00:02:43,220 --> 00:02:48,230 or one W and multiple spanning tree or 82.1 se. 32 00:02:48,530 --> 00:02:53,690 You can find this document as part of the course, or you can search in Google as an example for the 33 00:02:53,690 --> 00:02:56,000 Cisco AVID Network infrastructure. 34 00:02:56,830 --> 00:03:03,730 This document explains the evolution of spending tree and how spending tree has existed for a long time 35 00:03:03,730 --> 00:03:11,290 in an unchanged format, but has been enhanced through the use of rapid spending tree and multiple spending 36 00:03:11,320 --> 00:03:11,830 tree. 37 00:03:12,310 --> 00:03:19,180 Ed one D once again is the initial version of spending tree and was designed to stop loops in, switch 38 00:03:19,180 --> 00:03:21,040 to or bridged networks. 39 00:03:21,070 --> 00:03:27,040 It was very difficult to get foster convergence with ADA 2 to 1 D. 40 00:03:28,610 --> 00:03:32,700 One of the problems with Ada through one D is that it uses timers. 41 00:03:32,720 --> 00:03:36,680 Supports go from blocking to listening to learning to forwarding. 42 00:03:36,680 --> 00:03:40,280 And that process can take 50 seconds. 43 00:03:40,460 --> 00:03:47,180 When a port comes up as an example, it goes from listening to learning to forwarding, which takes 44 00:03:47,180 --> 00:03:48,410 30 seconds. 45 00:03:49,390 --> 00:03:57,910 Now Cisco enhanced ed one D in the 1990s by introducing uplink Fost Backbone Fost and Port Fost for 46 00:03:57,910 --> 00:03:59,600 the CCNA course today. 47 00:03:59,620 --> 00:04:02,980 You don't need to know about uplink Fost or Backbone Fost. 48 00:04:03,010 --> 00:04:04,720 You can just ignore those. 49 00:04:05,110 --> 00:04:13,390 The important one to remember is Port Fost or Edge ports, which are ports connected to end user devices 50 00:04:13,390 --> 00:04:18,850 such as PCs or servers that transition immediately to the forwarding state. 51 00:04:21,250 --> 00:04:25,990 The Triple E incorporated most of these concepts into two standards. 52 00:04:26,320 --> 00:04:29,140 Rapid spending tree and multiple spending tree. 53 00:04:29,650 --> 00:04:33,250 With these protocols, convergence timers were a lot quicker. 54 00:04:33,520 --> 00:04:38,710 Cisco have taken those protocols and enhanced PVS. 55 00:04:38,710 --> 00:04:43,150 T So today we have rapid pivot on Cisco switches. 56 00:04:43,970 --> 00:04:55,400 So as an example on the switch, we can type spanning tree mode and we can specify rapid PVS, PT or 57 00:04:55,400 --> 00:04:56,270 MST. 58 00:04:56,810 --> 00:05:04,460 The industry standard version of Rapid Spanning Tree only has one route in the entire topology, whereas 59 00:05:04,460 --> 00:05:10,310 a rapid PVS PT gives you a route on a per VLAN basis. 60 00:05:10,940 --> 00:05:18,320 So it's a lot better than pure, rapid, spanning tree or edited or one w multiple spanning tree doesn't 61 00:05:18,320 --> 00:05:27,080 give you a route per VLAN, but it gives you the ability to associate multiple VLANs to a spanning tree 62 00:05:27,080 --> 00:05:27,710 route. 63 00:05:27,920 --> 00:05:34,160 So you could say in a campus network as an example, that VLANs 1 to 100 have switched one as they route, 64 00:05:34,160 --> 00:05:38,750 but VLANs 101 to 200 have switched to as they route.