All language subtitles for Free-CCNA-Rapid-Spanning-Tree-Protocol-Day-22-CCNA-200-301-Complete-Course_en

This is a free, complete course for the CCNA.

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In this video we will continue our study of\n

version called rapid spanning tree.

More specifically, we’ll be looking at Cisco’s\n

You saw in the previous lecture that classic\n

to 50 seconds for the network to converge\n

As the name implies, rapid spanning tree improves\n

Because rapid spanning tree is superior to\n

most devices now, and the CCNA exam topics\n

However I think it is important to understand\n

about classic spanning tree, rapid spanning\n

Let’s take a look at what we’ll cover\nin this video.

First up, let’s take a few minutes to compare\n

In the past few videos I’ve mentioned multiple\n

Just so there is no confusion, I will summarize\n

standards and the Cisco proprietary versions.

Then the rest of the video will be all about\n

which operates on Cisco switches, rapid per-VLAN\n

Also, make sure to watch until the end of\n

a bonus question from Boson Software’s ExSim\n

the CCNA which I highly recommend.

Ask anywhere on the Internet for CCNA practice\n

If you want to get a copy of ExSim to prepare\n

Let’s start by summarizing the different\n

On the left I will list the industry standard\n

On the right I will list the Cisco proprietary\n

First up, the classic spanning tree protocol,\n

This is the original spanning tree protocol,\n

in 1990, although the original spanning tree\n

In classic STP, all VLANs share one STP instance.

Therefore, we cannot load balance using classic\n

cannot block different ports in each VLAN\n

So, Cisco decided to improve upon this.

They developed Per-VLAN Spanning Tree Plus.

Actually, before that they developed regular\n

before only supported ISL trunk encapsulation,\n

since everyone uses dot1q for their trunk\n

It’s Cisco’s upgrade to 802.1D. Each VLAN\n

In the previous lab video when we configured\n

command, for example spanning-tree vlan 1\nroot primary.

That’s because a separate STP instance is\nrunning for each VLAN.

Well, as you know already, we can load balance\n

We can use our network bandwidth more effectively,\n

totally unused, just waiting for another connection\nto fail.

Now, as you also know, classic spanning tree\n

The max age timer is 20 seconds, and the listening\n

it can take up to 50 seconds to respond to\n

That’s simply not fast enough for modern\nnetworks.

This was solved in rapid spanning tree protocol,\n

It is much faster at converging and adapting\n

like 802.1D, the industry standard rapid spanning\n

Therefore, it also cannot load balance.

Cisco once again developed an improved version\n

It is Cisco’s upgrade to 802.1w, featuring\n

a separate STP instance for each VLAN.

Therefore, it can load balance by blocking\n

The final version is Multiple Spanning Tree\n

It uses modified RSTP mechanics.

But the main improvement is that it can group\n

example if there are 10 VLANs, VLANs 1 to\n

2, to perform load balancing.

Finally an industry standard version of STP\n

superior to Cisco’s rapid-PVST.

If you have many VLANs, let’s say 200, in\n

root bridges in each VLAN is a lot of work.

However, with MSTP, all you have to do is\n

101 to 200 to instance 2, and then configure\n

instance 1 and instance 2, so its much easier\n

Actually, Cisco hasn’t developed their own\n

For large networks, it’s best to use MSTP,\n

a huge number of VLANs, Cisco’s Rapid PVST+\n

and that’s the version we’ll be focusing\non today.

It’s also the version that is mentioned\n

Also, all of this information here applies\n

version that runs on Cisco switches.

The good news is, since you already understand\n

to learn rapid STP and rapid PVST+ by comparing\n

Before getting in to the details, here is\n

RSTP is not a timer-based spanning tree algorithm\n

over the 30 seconds or more that 802.1D takes\n

The heart of the protocol is a new bridge-bridge\n

So, that’s the big difference between RSTP\n

determine when it’s safe to move to the\n

to ensure that no loops are accidentally created\n

Back when the original STP was created, it\n

50 seconds to react to a change and start\nforwarding traffic.

However that’s no longer the case.

So, RSTP uses a ‘handshake’ mechanism,\n

with other switches and move ports immediately\n

Okay, now I will introduce some of the specifics\nof RSTP.

By the way, I will probably say RSTP sometimes,\n

Really, I’m talking about the same thing.

Cisco’s Rapid PVST+ operates the same as\n

instance for each VLAN, so I will use the\n

Let’s summarize some similarities between\nSTP and RSTP.

First of all, RSTP serves the same purpose\n

RSTP elects a root bridge with the same rules\nas STP.

I’m sure you know it by now, the switch\n

RSTP also elects root ports with the same\nrules as STP.

So, the interface with the lowest root cost\n

neighbor bridge ID and then neighbor port\nID.

You studied this in day 20’s video, our\nfirst video on STP.

Finally, RSTP elects designated ports with\n

So, the interface on the switch with the lowest\n

on the other switch will be non-designated.

If there is a tie, the switch with the lowest\n

Cisco has said that RSTP isn’t a ‘revolution’\n

It made some major improvements to speed up\n

Now let’s look at some of the differences\nof STP and RSTP.

First up, port costs were updated for rapid\nspanning tree.

Classic spanning tree defines port speeds\n

than this are all given a cost of 1.

To accommodate for faster speeds, RSTP’s\n

2 million for 10 mbps, 2 hundred thousand\n

for 10 gbps, 200 for 100 gbps, and 20 for\n1 Tbps.

Beyond this, a 10 terabit-per-second interface\n

Use the flashcards to remember the port costs\n

Here’s a slide from day 21, the different\n

Hopefully you remember these states, which\n

traffic, which ones learn MAC addresses, etc.

However, rapid spanning tree simplifies the\n

three of these states into one.

The three states that are combined into one\n

Actually, a more accurate way is to say the\n

into one, and the listening state is simply\nnot used.

So, the listening state is gone, and the blocking\n

If a port is administratively disabled, meaning\n

it will be in a discarding state in RSTP.

This was previously the disabled state.

If a port is enabled but blocking traffic\n

This was previously the blocking state.

Remember, the three original port roles are\n

The root port role remains unchanged in RSTP.

The port that is closest to the root bridge\n

Of course, ‘closest’ means the port with\nthe lowest root cost.

Also, the root bridge is the only switch that\n

So, these points are the same as what you\n

The designated port role also remains unchanged\nin RSTP.

The port on a segment (which is another name\n

BPDU is that segment’s designated port,\n

The other port on the segment is either a\n

However, the non-designated port role was\n

Those are the alternate port role and the\nbackup port role.

Let’s break down those two roles.

First up, the alternate port role.

The RSTP alternate port role is a discarding\n

This is the same as what you’ve already learned\n

In our little topology down here, SW1 is the\nroot bridge.

When BPDUs are sent in this topology, SW3\n

It’s superior because the bridge ID of SW2\nis lower than SW3.

So, SW2’s interface is designated, and SW3’s\n

An alternate port basically functions as a\n

If the root port fails, the switch can immediately\n

If SW3’s root port fails, its alternate\n

port, with no transitional states.

This immediate move to forwarding state functions\n

Because it is built into RSTP, you do not\n

We didn’t look at UplinkFast in the previous\n

list, but try to remember that its functions\n

get asked about that on the exam.

So, UplinkFast is one STP optional feature\n

Since I just mentioned one, I’d like to\n

Neither of these are on the exam topics list\n

but just be aware of their general functionality,\n

One more STP optional feature that was built\n

Let’s say SW2’s root port is cut off,\n

It will then assume it is the root bridge,\n

However, SW3 is now receiving BPDUs from both\n

Without this backbonefast functionality, SW3\n

it’s non-designated port, in classic STP,\n

forwards the superior BPDUs to SW2, which\n

However, BackboneFast allows SW3 to expire\n

forward the superior BPDUs to SW2.

This functionality is built into RSTP, so\n

So, that’s a very basic explanation of BackboneFast.

Let’s look at a quick summary on the next\nslide.

UplinkFast and BackboneFast are two optional\n

They must be configured to operate on the\n

Both features are built into RSTP, so if the\n

They operate by default on all switches running\nRSTP.

Finally, You do not need to have a detailed\n

I recommend that you know their names and\n

ports move to forwarding without delay.

If you want to learn more, do a Google search\n

Learning how to effectively search on Google\n

a good network engineer, to be honest.

We Google things all the time in our daily\n

So, if you ever want to learn more about a\n

to improve your Google skills and try to search\n

Okay, after that little detour, let’s look\n

We just saw the alternate port role, which\n

we saw in the previous lectures.

Next up lets look at the backup port role.

The RSTP backup port role is a discarding\n

This only happens when two interfaces are\n

Notice that there is now an ethernet hub connected\n

When BPDUs are sent in this nework, the BPDU\n

by the hub, and as you can see here it receives\n

That’s why this interface is a backup port,\n

However, I’ve already told you that hubs\n

probably not encounter an RSTP backup port.

It’s still something you should know.

RSTP backup ports function as a backup for\na designated port.

If SW2’s designated port fails, its backup\n

Now, as for how the switch chooses which port\n

be the backup port, the interface with the\n

port, and the other will be the backup port.

Before moving on let’s try out a quiz question.

Identify the root bridge, and the RSTP port\n

By the way, the hub doesn’t participate\nin spanning tree.

Hubs aren’t sophisticated enough to use\n

Okay, pause the video here to find the answer.

The root bridge is SW1, because all switches\n

MAC address, it is elected as the root.

Its interfaces are designated ports.

These are the root ports for each switch.

SW2 and SW3’s root ports are obvious, they\n

The hub doesn’t participate in STP so it\n

It’s because the neighbor bridge ID is lower\n

SW2’s G0/1 connected to SW4’s G0/1 becomes\ndesignated.

Now, how about the connection between SW3\nand SW4?

First of all, which switch sets its interface\nto designated?

Well, SW3 has a lower root cost, so one of\n

G0/0 has the lower port ID, so it will be\n

How about SW3’s G0/1 and SW4’s G0/0?

SW3’s G0/1 receives the superior BPDU, with\n

SW4’s G0/0 receives the superior BPDU from\n

Hopefully you answered correctly.

If not, don’t worry, there will be more\n

Now let’s take a quick look at the CLI,\nI’m on SW3 here.

As I showed you in the last video, there are\n

Rapid-PVST is the default on modern Cisco\n

use this command, but I entered SPANNING-TREE\n

Then I used SHOW SPANNING-TREE to confirm.

Notice that it says ‘Spanning tree enabled\nprotocol rstp’.

Previously when we were using classic STP,\n

Although it says ‘rstp’, this is in fact\n

Now, the only other difference I want to point\nout is this.

As shown in the network diagram, SW3’s G0/1\n

The status is still listed as BLK for ‘blocking’,\n

I used the SHOW SPANNING-TREE command on SW4\nalso.

As in the network diagram, SW4’s G0/0 interface\n

Once again, this command lists the status\n

STP name for this state is actually ‘discarding’.

Just one note about running different STP\n

The interface, or interfaces, on the rapid\n

STP-enabled switch will operate in classic\n

to listening to learning to forwarding state\nprocess, etc.

So, if you have a really old switch that doesn’t\n

of rapid STP-enabled switches, they will adjust\n

So, in our network diagram, if SW4 was running\n

interfaces run in classic STP mode, but their\n

Next let’s look at the updated BPDU for\nRSTP.

Here on the left is the classic STP BPDU for\n

Most of the BPDU remains unchanged, but there\n

As I mentioned last time, you don’t need\n

You just need to know a few aspects of it\n

The first difference to know between these\n

has a protocol version of 2, whereas classic\n

Remember these version numbers for the exam,\n

The rapid STP BPDU also has a BPDU type of\n2.

Now, the next difference is here.

The classic STP BPDU uses only two bits of\n

However, the rapid STP BPDU uses all 8 bits.

These flags are used in the negotiation process\n

That’s all you really need to know about\n

But there is one more major difference.

In classic STP, only the root bridge originated\n

In rapid STP, ALL switches originate and send\n

Let’s go through a few other differences.

First, as I just said, all switches running\n

Switches also ‘age’ the BPDU information\nmuch more quickly.

In classic STP, a switch waits 10 hello intervals,\n

In rapid STP, a switch considers a neighbor\n

It will then ‘flush’, meaning delete,\n

Because the neighbor is down, it knows it\n

For example, in this network traffic from\n

But what if this connection is cut off?

This switch will think: I can’t reach this\nneighbor anymore.

I’ll clear all entries for this interface from\n

Then, if PC1 wants to send traffic to PC2\n

of flooding until it learns the MAC address\n

That’s just a quick look at how topology\n

There is a lot of depth that we could go into\n

If you want to go on to get your CCNP and\n

Before I summarize everything and move on\n

RSTP you should know, the RSTP link types.

RSTP distinguishes between three different\n‘link types’.

An edge port is a port that is connected to\nan end host.

It moves directly to forwarding without negotiation.

Well, the portfast functionality was built\ninto RSTP.

So, there’s another STP optional feature\n

The next link type is point-to-point.

This is used for direct connections between\ntwo switches.

However, there is one more type, although\n

This is a connection to a hub, like we saw\nearlier in the video.

These connections must operate in half-duplex\n

Don’t confuse these link types with the\n

Basically, the point-to-point and shared link\n

connections, and the edge type is a port that\nuses portfast.

Okay, let’s take a quick look at each type.

As I said, edge ports are connected to end\nhosts.

Because there is no risk of creating a loop,\n

without the negotiation process.

They function like a classic STP port with\nPortFast enabled.

In fact, you configure an edge port simply\n

Here is the command, just like in classic\nSTP.

So really, portfast and an RSTP edge port\nare the same thing.

In this network down here, which ports should\n

Pause the video if you want to think about\nit.

All of these ports, the ones connected to\n

These ports connect directly to another switch.

Because they connect to a switch, not a hub,\n

You don’t need to configure the interface\n

to detect that it is connected directly to\n

However, if you want to explicitly configure\n

SPANNING-TREE LINK-TYPE POINT-TO-POINT.

So, which connections in the diagram are point-to-point?

Pause the video to think about it.

It’s these three, the direct connections\nbetween two switches.

Finally, shared ports connect to a hub.

Due to the nature of hubs and the likelihood\n

Once again, you don’t need to configure\n

However, to manually configure it, use this\n

Although you should be aware of this type\n

probably never actually see this link type\n

that have been fully replaced by switches.

So, which connections in the diagram are shared\nconnections?

I think the answer is fairly obvious now,\n

So, these connections here are shared links.

Before moving on to the quiz, let’s summarize\n

First up, we compared the different versions\nof STP.

The classic STP is 802.1D, and Cisco’s upgrade\n

Then the next standard version is 802.1w,\n

Cisco’s version of this is Rapid PVST+,\n

Then there is one more industry standard,\n

create multiple spanning tree instances, and\n

There is no Cisco version of MSTP, Cisco switches\n

Then we looked at Rapid PVST+, but actually\n

to the industry standard RSTP as well.

RSTP is an evolution of classic STP.

Instead of using timers, it uses a negotiation\n

ports to a forwarding state, and rapidly adjust\n

I didn’t mention any specifics of the negotiation\n

I told you about the port states in RSTP,\nthere are only three.

Discarding, Learning, and Forwarding.

The listening state was deemed unnecessary,\n

due to the built-in features of rapid STP,\n

We talked about RSTP port roles, there are\nfour.

Root and designated ports are the same, but\n

Alternate ports are discarding ports which\n

Backup ports, on the other hand, receive a\n

This only occurs if connected to a hub, which\n

I also mentioned some optional features of\n

First I showed you UplinkFast and BackboneFast,\n

Although you have to know PortFast for the\n

of UplinkFast and BackboneFast.

I briefly showed you the RSTP BPDU, just remember\n

is 2, whereas in classic STP it’s 0.

Also remember the important point that in\n

Finally, I showed you the RSTP link types.

Edge ports are connected to end hosts, and\n

Point-to-point means it is connected directly\n

connected to a hub, and must use half-duplex.

As I said before, hubs aren’t really used\n

link type in any real networks.

Okay let’s move on to the quiz.

After a few quiz questions, let’s take a\n

for the CCNA, Boson Software’s ExSim.

Back before I started this YouTube channel,\n

and CCNP exams, and I really think ExSim played\n

The questions are very similar to the questions\n

depth explanations which really help deepen\n

Okay, now continuing on from quiz question\n

Which IEEE 802.1D optional features were built\n

ports to move rapidly to the forwarding state?

Pause the video to think about your answers.

The answers are B, portfast. D, uplinkfast, and e, backbonefast.

A, root guard, C BPDU guard, and F, loop guard,\n

are not features built in to RSTP that allow\n

G, rootfast, is not a real STP optional feature.

B, portfast, allows edge ports, connected\n

D, uplinkfast, and E, backbonefast, allow\n

You want to configure an 802.1w edge port,\n

begin sending traffic over the network immediately.

A, spanning-tree link-type edge.

C, spanning-tree link-type portfast.

Pause the video to think about your answer.

The answer is D, spanning-tree portfast.

Although ‘edge’ is a link type in RSTP,\n

command to configure it, and the command doesn’t\n

To configure an RSTP edge port, simply configure\n

Okay, let’s do one more quiz question.

Identify the root bridge in this network.

What is the RSTP port role of each switch\n(port)?

What is the appropriate RSTP link type of\n

This is a pretty long question, I recommend\n

and link types on the screenshot so you can\nremember everything.

Pause the video now to find the answers.

The root bridge is SW1, it has the lowest\npriority.

How about all of the root ports in the network?

SW4 picked it’s G0/0 interface because SW3\n

they have the same root cost because the hub\n

So, these are the designated ports.

Why was an interface on SW2 and not SW4\n

Because SW2 has the lower root cost.

Finally, the discarding interfaces.

Notice that there is one backup interface,\nSW2’s G0/2 interface.

This is because it receives a superior BPDU\n

Now, how about the link types?

All of these ports connected to end hosts\nshould be edge ports.

All of these full-duplex connections between\n

half-duplex connections with the hub are shared\nlinks.

If you had trouble with this, you should review\n

and if you still don’t understand feel free\n

Okay, now let’s check out a question from\nBoson ExSim for CCNA.

Okay, for today's Boson ExSim practice question,\n

something you just learned about.

Which of the following optional STP features\n

edge ports into a forwarding state?

And E, loop guard. Pause the video to think about your answer.

Okay, did you find your answer?

So, first of all what is an edge port?

Well it's a port at the edge of the network,\n

not the internal network between the switches.

So, which optional feature places ports connected\n

You should know the answer by now, it is C,\nPortFast.

If you're actually doing a practice exam you\n

but let's check the answer, show answer.

So you can see it gives quite a detailed explanation,\n

ExSim, about their practice exams.

Not only does it tell you why PortFast is\n

a brief summary of each of these other optional\nfeatures.

Loop guard, root guard, BPDU guard and BPDU\nfilter.

So you can know why they are not the correct\nanswer.

After all that it gives some references to\n

chapter 9, optional STP features.

And then also some Cisco documentation that\n

another great study resource by the way, Cisco's\n

Okay, if you want to get a copy of Boson ExSim\n

I used Boson ExSim myself for my CCNA and\n

in helping me pass all of my exams on the\nfirst try.

So once again, please click that link in the\n

There are supplementary materials for this\nvideo.

There is a flashcard deck to use with the\n

link in the description and use the flashcards\n

There will also be a packet tracer practice\n

That will be in the next video.

Before finishing today’s video I want to\n

Thank you to tibi, vikram, Joyce, Marek, Samil,\n

Yousif, Kone, Boson Software, the creators\n

Lito, Yonatan, Mike, Aleksander, Vance, and\nGerrard.

Sorry if I pronounced your name incorrectly,\n

One of you is still displaying as Channel\n

me know and I’ll see if YouTube can fix\nit.

This is the list of JCNP-level members at\n

2020, if you signed up recently and your name\n

Please subscribe to the channel, like the\n

with anyone else studying for the CCNA.

If you want to leave a tip, check the links\nin the description.

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