1 00:00:00,610 --> 00:00:07,060 He has a quick summary of the different types of spending tree and the advantages and disadvantages 2 00:00:07,060 --> 00:00:07,750 of each. 3 00:00:07,990 --> 00:00:13,450 So the original version of Spending Tree is the triple E, a 2.1 D spanning tree. 4 00:00:13,840 --> 00:00:19,590 This is the legacy standard of spending tree that was used when bridges were around. 5 00:00:19,600 --> 00:00:24,700 So it's very old, but it's the basis of other versions of Spending Tree. 6 00:00:24,880 --> 00:00:29,440 You'll also see the term C is DT or common spanning tree. 7 00:00:29,680 --> 00:00:35,380 This assumes that there is one spanning tree instance for the entire bridged network, regardless of 8 00:00:35,380 --> 00:00:36,730 the number of VLANs. 9 00:00:36,970 --> 00:00:39,430 We don't use that today in Cisco environments. 10 00:00:39,580 --> 00:00:44,170 We use a version of per VLAN, spanning tree or PVS. 11 00:00:44,230 --> 00:00:46,420 DT Originally PvZ. 12 00:00:46,420 --> 00:00:49,690 DT Only supported ESL PvZ. 13 00:00:49,690 --> 00:00:52,390 DT Plus supports ESL and ADA 2.1. 14 00:00:52,390 --> 00:00:57,490 Q But today we often refer to PVS plus as PVS DT. 15 00:00:57,700 --> 00:01:03,880 So this is a Cisco enhancement of spending tree that provides a separate ed to one DX spanning tree 16 00:01:03,880 --> 00:01:06,040 instance for every VLAN. 17 00:01:06,310 --> 00:01:12,520 If you had 100 VLANs, you would end up having 100 instances of spanning tree. 18 00:01:12,820 --> 00:01:19,810 Each spanning tree would have its own route and would do its own calculations in Cisco environments. 19 00:01:19,930 --> 00:01:24,730 Each spanning tree would send its own BPD use or bridge protocol data units. 20 00:01:25,090 --> 00:01:34,630 So if you had 100 VLANs every 2 seconds, a hundred BPD user sent multiple spanning tree tries to optimize 21 00:01:34,660 --> 00:01:40,330 PVS DT by mapping multiple VLANs to the same spanning tree instance. 22 00:01:40,330 --> 00:01:48,070 So 82.1 SW or multiple spanning tree allows you, for example, to have two spanning tree instances 23 00:01:48,070 --> 00:01:50,170 and then split your VLANs. 24 00:01:50,170 --> 00:01:57,550 Between those instances, VLANs 1 to 100 could be associated with instance one. 25 00:01:58,150 --> 00:02:03,220 VLANs 101 to 200 could be associated with instance two. 26 00:02:03,670 --> 00:02:11,410 That provides a lot of advantages in that you have two instances of spanning tree rather than 200, 27 00:02:11,410 --> 00:02:14,310 which you would have if you used PVS. 28 00:02:14,320 --> 00:02:21,280 DT Multiple spanning tree also has rapid spanning tree built into it, so it converges very quickly. 29 00:02:21,520 --> 00:02:30,280 Rapid spanning tree or ADA 2 to 1 W improves convergence over the 1998 version of Spanning Tree by adding 30 00:02:30,280 --> 00:02:34,600 roles to ports and enhancing BPU exchanges. 31 00:02:35,410 --> 00:02:41,260 It provides for much quicker convergence when compared to traditional spending tree. 32 00:02:41,710 --> 00:02:42,640 Rapid spending tree. 33 00:02:42,670 --> 00:02:48,070 However, only supports a single instance of spending tree. 34 00:02:48,370 --> 00:02:51,900 So all the lands are mapped to that single instance. 35 00:02:51,910 --> 00:02:58,990 And this is why we have a rapid pivot plus on Cisco switches that allows us to have one spanning tree 36 00:02:58,990 --> 00:03:02,710 instance per VLAN but have rapid convergence. 37 00:03:03,100 --> 00:03:08,830 Now multiple spanning tree has the advantage that you can map multiple VLANs to a single instance of 38 00:03:08,830 --> 00:03:09,610 spanning tree. 39 00:03:09,970 --> 00:03:13,870 That, however, only becomes important when you have many VLANs. 40 00:03:14,350 --> 00:03:18,460 If, for example, you only have ten VLANs in your enterprise. 41 00:03:18,490 --> 00:03:26,050 Rapid pivot plus works really well and hence it's the default spanning tree on Cisco switches. 42 00:03:26,380 --> 00:03:33,250 You would only necessarily need to use multiple spanning tree if you had hundreds or thousands of VLANs. 43 00:03:33,580 --> 00:03:41,320 So the default today on most Cisco switches is rapid PvP plus provides rapid convergence and allows 44 00:03:41,320 --> 00:03:48,340 you to configure one spanning tree instance per VLAN to optimize performance in the videos. 45 00:03:48,340 --> 00:03:55,090 In this course, I'll show you a campus network where we optimize spanning tree by splitting the load 46 00:03:55,090 --> 00:03:57,340 between different switches. 47 00:03:57,640 --> 00:04:03,190 In other words, one switch will be the spanning tree route for some VLANs and another switch will be 48 00:04:03,190 --> 00:04:05,320 the spanning tree route for other VLANs.