1
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So let's look at that practically.

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Yeah I've got to switch one switch to and switch three switch to switch three or connected to a hub.

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So that's following the typologies shown in this Cisco guide.

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I've just booted up the switches so you can see that coming up at the moment.

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So these are brain switches with no configuration at all.

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OK so in switch one set to the host name to switch one switch to set the host name to switch to.

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You may be able to hear that by C.P. you is maxed out all the switches are booting up at the moment

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my genius 3 VM is at 87 percent the local CPQ 62 percent but that'll settle down in a moment which it

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now has so schola shows spanning tree shows spanning tree at the moment to the switches not to the route.

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You can see it's a path cost to get to the route on gigabit.

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0 1 so I'm assuming that switch 3 is the route.

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Show spending tree we can see in the output here.

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That to switch three is the route to switch of the topology.

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So I'll change that Nick.

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I'll just touch one and top spending tree.

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Vigeland One bricht And actually I'll just set it by priority so priority and let's set it to zero.

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So show spanning tree we can see that the switch is now the root of the spinning tree for villaine one.

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We are running Reppert Peavey's on the switch.

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Some ports are still in the learning state.

20
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But there they go to Fording.

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So we can see all ports in the switch all forwarding.

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Those are the two ports of interest and which one

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on switch to show spending tree

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so is the commission show spending tree we running Reppert spending tree Poth just to get to the root

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is 4 out of portal 1 which is kickabout 00 gigabit 00 is the root port.

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And notice how gigabit is 0 1 is the old turn of port on the switch.

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It's in the blocking state.

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That's what we learnt in the Cisco document.

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An alternate port on the switch means that there is a port on another switch that's the designated port.

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In other words it has a better path to get to the root bridge.

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So let's look at Switch three shows spending tree on switch three.

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It has a path to fall out of port 1 which is gigabit 0 0.

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So this is the route port of switch three.

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We can see that here once again gigabit 0 0 is the root port and the output to Gigabit is 0 1 is the

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designated port and gigabit.

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0 2 is the backup port backup port is in the blocking state alternate port on switch to is in the blocking

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state.

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So this port is blocking this port is blocking.

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This is the only port that is forwarding on this segment connected to the hub.

40
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So loops will be blocked in the apology even though we connected to a hub that demonstrates the port

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roles and status that you get interrupted spending tree on switch to once again just move this up a

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bit.

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So on switch to connect to the hub on gigabit 0 1 gigabit 0 1 is an old turn at port.

44
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That is the role the status of the port is blocking gigabit 0 00 on that switch is a recruit port.

45
00:04:20,290 --> 00:04:28,450
That is the role and the status is forwarding on switch 3 gigabit 00.

46
00:04:28,490 --> 00:04:31,130
This port is the root port.

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It has a status of forwarding.

48
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That's the best port to use to get to the root bridge.

49
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Gigabit is 0 1.

50
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In other words this connection is the designated port.

51
00:04:42,770 --> 00:04:50,650
The role is designated the status is forwarding this interface gigabit to 0 2 is a backup port.

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That is the role the status is blocking.

53
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So blocking or discarding to use the industry standard term is the state of alternative as well as backup

54
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ports router ports and designated ports have the forwarding status in a stable topology a state of learning

55
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means that traffic is still being discarded on the port.

56
00:05:16,850 --> 00:05:17,930
So as an example

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on gigabit 00 I'll shut the port down show spending tree notice gigabit to 0 or 1 is now forwarding

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gigabit to 0 2 is the alternate port.

59
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It's in a blocking state

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the port here is now the designated port.

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It's in the learning status which will hopefully move to forwarding in a moment.

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And there you go.

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The reason why it took time to transition to the forwarding state is that this is a shared port not

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a point to point Port point to point ports transition immediately to forwarding Schade ports.

65
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Don't they have to go through the timer's of learning and then forwarding.

66
00:06:06,990 --> 00:06:14,730
So scrolling up we saw a learning state and then it went to the forwarding state.

67
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That's because it's a shared port which means a half duplex interface which is connected to a hub.

68
00:06:21,450 --> 00:06:27,360
This port should be configured as a point to point link because it's a direct connection from one switch

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to another.

70
00:06:28,500 --> 00:06:37,350
So as an example what we should be doing is on gigabit 00 we should top spending tree linked type point

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to point and we want to do that on both sides.

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Typically in the real world your switches would negotiate a point to point link if the Duplaix was set

73
00:06:48,450 --> 00:06:57,570
to full we'll do something similar on switch three gigabit 00 should be point to point and gigabit 0

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00:06:57,560 --> 00:06:58,750
1 should be point to point.

75
00:06:58,750 --> 00:07:02,860
In other words this link point to point the Slinky's point to point.

76
00:07:02,860 --> 00:07:09,880
So back on switch to shows spending tree noticed the port type point to point which allows for quicker

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convergence on which one show spending tree both gigabit 00 and gigabit zero one point to point links.