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These are the user uploaded subtitles that are being translated: 1 00:00:00,000 --> 00:00:05,000 align:middle line:84% So here’s a quick comparison of the different versions of Spanning Tree. 2 00:00:05,000 --> 00:00:10,000 align:middle line:84% The Spanning Tree 802.1D protocol doesn’t need a lot of resources 3 00:00:10,000 --> 00:00:12,000 align:middle line:84% but it slow to converge. 4 00:00:12,000 --> 00:00:18,000 align:middle line:84% You only have 1 Spanning Tree instance for your entire layer 2 network. 5 00:00:18,000 --> 00:00:22,000 align:middle line:84% This can lead to sub-optimal traffic flows 6 00:00:22,000 --> 00:00:28,000 align:middle line:84% and 802.1D is generally not used today in Cisco environments. 7 00:00:28,000 --> 00:00:33,000 align:middle line:84% Just be aware that when you use newer versions of Spanning Tree 8 00:00:33,000 --> 00:00:35,000 align:middle line:84% Cisco switches are backward compatible 9 00:00:35,000 --> 00:00:42,000 align:middle line:84% and can talk to all the switches or non-Cisco switches using 802.1D 10 00:00:42,000 --> 00:00:44,000 align:middle line:84% PVST is the Cisco enhancement 11 00:00:44,000 --> 00:00:49,000 align:middle line:84% that provides a single instance of Spanning Tree per-VLAN. 12 00:00:49,000 --> 00:00:53,000 align:middle line:84% It's Cisco propriety, it needs more resources 13 00:00:53,000 --> 00:00:57,000 align:middle line:84% because 1 Spanning Tree instance is created per-VLAN. 14 00:00:57,000 --> 00:01:03,000 align:middle line:84% It is still slow to converge but thus allow you to split traffic flows 15 00:01:03,000 --> 00:01:07,000 align:middle line:84% because you have 1 Spanning Tree instance per VLAN. 16 00:01:07,000 --> 00:01:12,000 align:middle line:84% as an example, VLAN 1 traffic could use 1 uplink 17 00:01:12,000 --> 00:01:18,000 align:middle line:84% but VLAN 2 traffic could use as separate uplink or a separate port in a network. 18 00:01:18,000 --> 00:01:22,000 align:middle line:84% Cisco have also enhanced PVST with features 19 00:01:22,000 --> 00:01:28,000 align:middle line:84% such as Portfast, Uplink fast, backbone fast, BPDU guard, BPDU filter 20 00:01:28,000 --> 00:01:34,000 align:middle line:84% root guard and loop guard we'll discuss some of those terms in this course 21 00:01:34,000 --> 00:01:39,000 align:middle line:84% otherwise, you'll learn more about those when you attend your CCMP courses. 22 00:01:39,000 --> 00:01:44,000 align:middle line:84% Rapid Spanning Tree Protocol or 802.1W is an industry standard protocol 23 00:01:44,000 --> 00:01:47,000 align:middle line:84% it doesn’t need as many resources as PVST+ 24 00:01:47,000 --> 00:01:52,000 align:middle line:84% because it supports a single instance of Spanning Tree for your layer 2 network. 25 00:01:52,000 --> 00:01:57,000 align:middle line:84% Its big advantage is that it provides very quick or fast convergence. 26 00:01:57,000 --> 00:02:02,000 align:middle line:84% It also doesn’t address suboptimal traffic flow issues 27 00:02:02,000 --> 00:02:07,000 align:middle line:84% because you can send VLAN 10 traffic for example down 1 link 28 00:02:07,000 --> 00:02:10,000 align:middle line:84% and VLAN 20 traffic down another link. 29 00:02:10,000 --> 00:02:12,000 align:middle line:84% That’s the advantage of Rapid PVST+ 30 00:02:12,000 --> 00:02:17,000 align:middle line:84% Rapid PVST+ incorporates the advantages of Rapid Spanning Tree 31 00:02:17,000 --> 00:02:22,000 align:middle line:84% but allows you to create 1 spanning tree instance per-VLAN 32 00:02:22,000 --> 00:02:27,000 align:middle line:84% so you can do load sharing of traffic, it provides very quick convergence 33 00:02:27,000 --> 00:02:32,000 align:middle line:84% but uses a lot of resources especially when you’ve got many VLANs. 34 00:02:32,000 --> 00:02:34,000 align:middle line:84% The advantage of Multiple Spanning Trees 35 00:02:34,000 --> 00:02:40,000 align:middle line:84% is that it solves that high resource issue of PVST+ 36 00:02:40,000 --> 00:02:45,000 align:middle line:84% Multiple Spanning Trees allows you to create an instance of Spanning Tree 37 00:02:45,000 --> 00:02:49,000 align:middle line:84% and then map various VLANs to that instance. 38 00:02:49,000 --> 00:02:57,000 align:middle line:84% As an example, once again if you had 200 VLANs PVST or Rapid PVST 39 00:02:57,000 --> 00:02:59,000 align:middle line:84% would require 200 instances of Spanning Tree 40 00:02:59,000 --> 00:03:04,000 align:middle line:84% where’s Multiple Spanning Tree could use 2 instances to do load sharing 41 00:03:04,000 --> 00:03:07,000 align:middle line:84% and reduce the amount of resources required. 42 00:03:07,000 --> 00:03:11,000 align:middle line:84% So CPU and memory requirements for Multiple Spanning Trees 43 00:03:11,000 --> 00:03:15,000 align:middle line:84% are lower than those for Rapid PVST+ 44 00:03:15,000 --> 00:03:20,000 align:middle line:84% but resources are higher than those for Rapid Spanning Tree. 45 00:03:20,000 --> 00:03:24,000 align:middle line:84% Now you may find reference materials stating that PVST+ 46 00:03:24,000 --> 00:03:27,000 align:middle line:84% is the default Spanning Tree on Cisco switches 47 00:03:27,000 --> 00:03:31,000 align:middle line:84% that really depends on a lot of switches today use Rapid PVST 48 00:03:31,000 --> 00:03:36,000 align:middle line:84% is the default version of Spanning Tree. 5819