1
00:00:00,090 --> 00:00:07,110
In this video we're going to discuss spanning tree spanning tree was developed to stop a layer two loops

2
00:00:07,140 --> 00:00:09,510
occurring in switched environments.

3
00:00:10,300 --> 00:00:17,500
In transparent switching or transparent bridging, which is what Ethernet uses redundant links, introduce

4
00:00:17,500 --> 00:00:21,460
loops and spanning trees used to stop those loops.

5
00:00:22,240 --> 00:00:27,730
Spanning tree has been around for many years and there have been multiple developments and enhancements.

6
00:00:27,730 --> 00:00:30,760
So this is one of the challenges that you're going to face.

7
00:00:30,790 --> 00:00:36,250
They are different implementations and versions of Spanning Tree and you'll need to know some of those

8
00:00:36,250 --> 00:00:37,180
differences.

9
00:00:38,060 --> 00:00:38,510
Spending.

10
00:00:38,510 --> 00:00:44,660
Trees are very important protocol in traditional networks, and once again, its primary purpose is

11
00:00:44,660 --> 00:00:51,470
to stop loops in a switched environment and not necessarily to stop them as quickly as we would like.

12
00:00:51,710 --> 00:00:58,010
Spanning Tree was developed many years ago, originally being developed for bridges rather than switches,

13
00:00:58,010 --> 00:01:00,980
and thus at times is very slow to converge.

14
00:01:01,070 --> 00:01:06,230
In other words, it takes a long time for traffic to be rerouted if there's a change in the network

15
00:01:06,230 --> 00:01:07,130
topology.

16
00:01:07,490 --> 00:01:13,070
Spanning Tree was once again originally developed for bridges, and bridges did their calculations in

17
00:01:13,070 --> 00:01:17,750
software rather than in hardware, which is what switches do today.

18
00:01:18,200 --> 00:01:24,710
So in the past, slower convergence was fine, but that's a major problem in today's environments where

19
00:01:24,710 --> 00:01:31,310
we run voice over IP or other protocols that require very quick convergence.

20
00:01:32,170 --> 00:01:40,090
Thus the original standard spanning tree or ADA 2.1 dx spanning tree has been superseded by newer versions

21
00:01:40,090 --> 00:01:43,750
such as rapid spanning tree and multiple spanning tree.

22
00:01:44,590 --> 00:01:51,970
Because spending trees of great importance for the CCNA certification as well as for real deployments.

23
00:01:52,090 --> 00:01:58,420
I'm going to start off with the original version of spanning three 802 to 1 DX and then we'll build

24
00:01:58,420 --> 00:02:05,320
on those concepts looking at more and more complex topologies and other versions of Spanning Tree.