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In this typology I have two switches are which are configured to to run previous t not rapid previously

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plus but simply previous t.

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I'll show you that config in a moment.

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Rodda one is connected to switch 1 and router 2 is connected to switch 2 and the rods are simply acting

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as edge devices or PCs in this topology.

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I've also got a hub connected to switch one and switch to just switch one show run pipe include spanne

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as you can see at the moment the switches is configured for previous t well-explained extended system

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IDs in more detail later.

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But essentially it means that the priority of the switches based on the priority and a villain number.

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So as an example shows spending tree the switch has a bridge ID consisting of the priority 3 2 7 6 9

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which is the default of 3 2 7 6 8 plus the extended system id of one because we are looking at a villain

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one and MAC address of the following.

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The switch is currently the route.

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What I want you to see is that the spending tree enabled here is I triple E.

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So in this output it looks like Im running a two to one D but actually the switch is configured for

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Poovey LAN spending tree povi and spinning tree is compatible with Ada 2 to 1 D switches and therefore

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we can see Triple E and the output here has switched to show run type.

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Include spanne which is configured to use PV is t extended system IDs are being used

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on the switch.

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The bridge idea consists of the property 3 to 7 6 and 9 which is 3 2 7 6 8 2 the default plus the villain

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number which is veel and 1 in this example.

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This is the MAC address of the switch.

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So we have two switches.

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One has the MAC address.

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One has the MAC address so which one has become the root of the spending tree because it has a lower

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MAC address when compared to the switch.

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So because of the lower MAC address notice a c is lower than E-A in hexadecimal.

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So which one became the root of the spanning tree what you also notice is that on switch 1 all ports

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or forwarding in the topology the ports that are currently connected are those ports and they all forwarding

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on switch to however Pt. 1 which is gigabit 00 is the root port and it's forwarding has a path cost

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of four gigabit.

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0 1 is blocking or discarding to use the industry standard term.

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Pt. 2 is forwarding port three is blocking.

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So this port is also blocking route switches forward on all ports.

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Before I show you how port status is determined Let's have a look at the BBC's

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historic capture on that link and what we can see here in Wireshark is a spanning tree BPT.

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So it's using a two or three Ethernet Frayne's.

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Notice the destination address is the well-known Mac address for spending tree it is a multi-course

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broadcast address from the Mac address.

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Yes which one notice the Mac address of the switch is 0 0 11 C 6 a c d d and we currently looking at

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ports 3 on the switch.

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So I notice Didi's 0 0 but this is Didi's 0 3 because in spending tree that's the portal we currently

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looking at if we went and looked at port 2 as an example

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notice the Mac address ends in 0 2.

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We've got port 0 0 0 1 0 2 0 3.

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So back in Wireshark he has our capture sent out of Port three in spanning tree we can see the spanning

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tree version.

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So the suspending tree is 0 because in this port it's actually using Ada 2 the one d or the original

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version of spanning tree the route identifier is 3 2 7 6 8 is the villain number and there's the Mac

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address of the switch which we can see clearly here.

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So notice route identifier is the information of 6:57 6:8.

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Villain 1 there is the Mac address of the switch.

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The root path cost is zero because the switch is the root.

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So there's no cost to get to the root base.

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The port identifier and here all some time is used in spending tree.

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Now when a switch boots up all ports are put into the blocking state they then move to other states

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based on time as an aid to the one D when a spending tree switch boots up all ports are put into the

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blocking state off to 20 seconds called the max a timer ports move to what's called the listening state.

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If a switch is ready up and you connect a cable to the port.

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In other words the link goes up.

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It starts at the listening state.

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Ports will then move to the learning state based on the forward delay which is 15 seconds in generation

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and after 15 seconds Portes transition from the learning state to the forwarding state.

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So an edit to the one d or PV t it can take 50 seconds for ports to start forming on switches because

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they move from blocking to listening to learning to forwarding.

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Now in the listening states they are sending BPT use but not updating their mac address tables in the

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learning state BPT use a.

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And the MAC address tables of switches are updated.

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So only if based on the spending tree calculation it's determined that a port can be opened a port is

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set to the forwarding state after 50 seconds when a switch comes up.

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Typically if a switch is already up and you plug the cable into that switch after 30 seconds the port

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will start forwarding.

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So in the PPD you can see the max age timer and the forwarding delay timer.

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This is determined by the route bridge.

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So on switch one which is the route bridge we can see that the holloed timer.

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In other words BPT Hello's are sent out every two seconds.

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The max age time is 20 seconds and the forwarding delay timer is 15 seconds.

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And that's what we see in the BPT use as captured in our typology.