All language subtitles for Free-CCNA-VLANs-Part-2-Day-17-CCNA-200-301-Complete-Course_en

This is a free, complete course for the CCNA.

If you like these videos, please subscribe\n

Also, please like and leave a comment, and\n

In this video we will continue with the topic\n

In the last video, Day 16, we covered the\n

what their purpose is, and the most basic\nVLAN configurations.

However, that’s not really enough information,\n

to be able to understand and use VLANs.

That’s what we’ll cover in today’s video.

So let’s take a look at what we’ll cover, exactly.

This will be a fairly long video I think,\n

First of all, what is a trunk port?

I mentioned trunk ports briefly in the last\nvideo.

Whereas an access port belongs to a single\n

Next, what is the purpose of trunk ports?

Next I will talk about 802.1Q encapsulation.

This is an additonal tag added to an Ethernet\n

Next, we’ll go into trunk port configuration,\n

Finally, we’ll cover ‘router on a stick’.

It’s a bit of an odd name, but this is something\n

It’s a more efficient way of performing\n

a separate router interface for every VLAN.

For a quick review, here is the network topology\n

There is a single switch, and three VLANs.

All of the switch interfaces are access ports\n

Three interfaces are used to connect to the\n

For this video, let’s use a different network\ntopology.

Here’s the network topology we’ll start\nwith for this lesson.

This time, there are two switches used.

Note that VLAN10, the VLAN for the engineering\n

This is very common, as departments in a company\n

You might have some engineers on one\n

We are still using only access ports.

There are two links between SW1 and SW2, one\n

There must be a link in VLAN10 between the\n

to both SW1 and SW2, and also because the\n

As for the link in VLAN30, it is necessary\n

There is no link in VLAN20 between SW1 and\nSW2.

This is because there are no PCs in VLAN20\nconnected to SW1.

PCs in VLAN20 can still reach PCs connected\n

Let me demonstrate that inter-VLAN routing.

Let’s say this PC in VLAN20 wants to send\n

It will send the frame with a destination\n

R1 then forwards it back to SW2.

Note that this traffic arrived at SW2 on the\n

so it forwards it to SW1 on the VLAN10 connection\n

So, you can see that, even though there isn’t\n

PC in VLAN20 can still send traffic to the\n

In a small network with few VLANs, it is possible\n

when connecting switches to switches, and\nswitches to routers.

However, when the number of VLANs increases,\nthis is not viable.

It will result in wasted interfaces, and often\n

You can use 'trunk ports' to carry traffic from\n

Once again, these are different than access ports, which belong to

Let’s take a quick look at how trunk ports\nwork.

So, now I’ve replaced those separate connections\n

between SW1 and SW2, and SW2 and R1.

However, to make it more clear, let’s add\nthose colors back.

Okay, so now you can see which VLANs are allowed\non each trunk.

Remember, these are single physical connections,\n

Let’s say this PC in VLAN10 wants to send\n

It sends the traffic to SW2, which then sends\nit to SW1.

How does SW1 know which VLAN the traffic belongs\nto?

Both VLANs 10 and 30 are allowed on the interface\n

SW1 know which VLAN it belongs to?

Switches will ‘tag’ all frames that they\nsend over a trunk link.

This allows the receiving switch to know which\n

In fact, another name for a trunk port is\n

an access port is an ‘untagged’ port.

Frames sent over access ports aren’t tagged,\n

interface belongs to a single VLAN.

If a frame arrives on a switchport in VLAN10,\n

Let’s talk about those VLAN tags.

There are two main trunking protocols: ISL\n

ISL is an old Cisco proprietary protocol,\n

802.1Q. Dot1q is an industry standard\n

Electrical and Electronics Engineers).

That’s Ethernet, another industry standard\nprotocol.

You will probably NEVER use ISL in the real\nworld.

Even modern Cisco equipment doesn’t support\nit.

For the CCNA, you only need to learn dot1q.

You should know what ISL is, but you don’t\n

Okay here’s an old slide, back from Day\n5 on Ethernet switching.

Do you remember the fields of the Ethernet\nheader and trailer?

If you don’t, I recommend going back to\n

time explaining it all again here.

However, the reason I am showing this is because\n

two fields of the Ethernet header.

So, here’s just the Ethernet header.

Dot1q inserts a 4-byte, or 32-bit field between\n

As you can see here, the dot1q tag is inserted\n

or length fields of the Ethernet header.

As I just said, the 802.1Q tag is inserted\n

The tag is 4 bytes, or 32 bits, in length.

The tag consists of two main fields.

Those are the Tag Protocol Identifier, TPID,\n

The TCI itself consists of three sub-fields.

Let’s quickly take a look at each field\nof the dot1q tag.

Here’s a diagram of the dot1q tag format,\nthanks to wikipedia.

Notice that it can be divided into two halves,\n

Also, the TCI can be divided into three sub\n

Okay first up lets look at the TPID field.

The field is 16 bits, or 2 bytes, in length,\n

The TPID is ALWAYS set to a value of 0x8100.

Remember, 0x just means hexadecimal, so the actual\n

Each hexadecimal digit is 4 bits, so 4 x 4\n

This value of 8 1 0 0 indicates that the frame\nis dot1q-tagged.

As I just showed you, the dot1q tag comes\n

This is where the TYPE field is usually located.

When the switch sees this value of 8 1 0 0\n

Okay, that’s all for the TPID field.

Next up let’s look at the first field of\n

It is used for Class of Service, CoS, which\n

Don’t worry about this field too much, just\n

Next up is the DEI, Drop Eligible Indicator.

This field is just a single bit in length.

It is used to indicate frames that can be\n

makes sure more important network traffic\ngets through.

Once again, you don’t really need to worry\n

know the name and it’s basic purpose.

Okay, finally is a very important field, the\n

It is the field that actually identifies the\n

this is the most important field of the dot1q\ntag.

Because this field is 12 bits in length, that\n

2 to the power of 12 equals 4096.

However, the first and last VLANs, 0 and 4095,\n

Therefore, the actual range of VLANs that\n

By the way, Cisco’s proprietary ISL, which\n

over trunk connections, also uses a VLAN range\nof 1 to 4094.

As I mentioned before, however, you don’t\n

completely replaced by the industry standard\ndot1q.

So, those are the fields of the dot1q tag.

Take a look at this diagram, do you remember\n

If you want to read a little bit about dot1q,\n

Okay let me talk about the VLAN ranges a little\nbit more.

The range of VLANs, which as I mentioned is\n

'normal VLANs', which are numbered from 1 to\n

Some older devices cannot use the extended\n

that modern switches will support the extended\nVLAN range.

I work with Cisco switches a lot in my job,\n

doesn’t support the entire range, from 1\nto 4094.

Just be aware that some older switches might\n

Okay, so let’s look at this diagram once again.

So, this PC in VLAN10 wants to send\n

The traffic goes to SW2, which then forwards\n

SW1 receives the frame, and because the destination\n

Remember, a standard layer 2 switch like this\n

it will not forward traffic between VLANs.

Let me introduce another concept of dot1q.

Dot1q has a feature called the NATIVE VLAN.

Cisco’s ISL does not have this feature,\nby the way.

The native VLAN is VLAN 1 by default on all\n

It’s important to remember that this has\n

a global configuration on the switch.

Now, what exactly does the native VLAN do?

The switch does not add an 802.1Q tag to frames\n

It will forward the frame normally, without\n

So, what does the receiving switch do when\n

When a switch receives an untagged frame on\n

So, it’s very important that the native\n

Switches will still forward traffic if there\n

This time, let’s say I’ve configured the\n

Let’s follow some traffic on the same path\nas usual.

This PC sends the traffic to SW2.

It will send the traffic to SW1, but because\n

The untagged frame arrives at SW1, which assumes\n

forwards it to the destination.

This time, let’s look at if there is a native\n

On SW2’s interface I’ve configured VLAN10\nas the native VLAN.

However, on SW1’s interface I’ve configured\n

Up to the point the traffic reaches SW1, it’s\nthe same.

However, when SW1 receives the frame this\nis what it will think.

Therefore, it must belong to VLAN30.

But, the destination is in VLAN10, not VLAN30.

So, I won’t forward the frame.

So, I think you can see why it is important\n

Let’s look at another reason why it’s\n

This time, this PC in VLAN10 wants to reach\nthis PC in VLAN30.

The PC sends the frame to SW2, which forwards\n

However, VLAN30 is the native VLAN of SW1.

When this frame tagged with VLAN30 arrives,\n

not forward it to the destination.

Because it expects all traffic in VLAN 30\n

will consider the frame to be an error, and\nnot forward it.

So once again, make sure the native VLAN matches\non each switch!

Okay, let’s finally get into the configuration\nof trunk ports.

I’ve added the interface numbers to the\n

So, we will be configuring G0/0 on SW1,\n

First let’s look at the most basic trunk\n

After entering interface configuration mode,\n

manually configure the interface as a trunk.

However, in this case we got an error message.

Command rejected, an interface whose trunk\n

Many modern switches do not support Cisco’s\nISL at all.

Even though ISL is a proprietary Cisco protocol,\n

However, switches that do support both dot1q\n

example) have a trunk encapsulation of ‘Auto’\nby default.

To manually configure the interface as a trunk\n

On switches that only support dot1q, this\nis not necessary.

After you set the encapsulation type, you\n

So, let’s see how to set the encapsulation\ntype.

You use the SWITCHPORT TRUNK ENCAPSULATION\ncommand.

I used the question mark to see the options.

There are dot1q, isl, and negotiate.

Negotiate sets it to AUTO mode, so we cant\nchoose that.

I will talk more about AUTO mode in the next\n

questions I will answer them there.

I set the encapsulation to dot1q, and then\n

On switches that only support dot1q, you will\n

but on some switches you will need to set\n

I used the SHOW INTERFACES TRUNK command to\nconfirm.

First up, the trunk interfaces are listed\nhere.

'Mode on' means that the interface was manually\n

In the next lecture we will look at how a\n

configuration, but we’ll forget about that\nfor the moment.

Encapsulation is dot1q as we configured, status\n

mentioned before, is the default of 1.

Under that, the VLANs allowed on the trunk\nare displayed.

By the default, ALL VLANs, 1 to 4094, are\nallowed on the trunk.

However, for security purposes, we might want\n

trunk, so we’ll look at that configuration next.

Next up is VLANs allowed and active in management\ndomain.

This includes the default VLAN of 1, as well\n

Note that, although VLAN1, which exists by\n

which I showed you in the previous lecture\nvideo, do not.

As I mentioned before, don’t worry about\n

The last field of the SHOW INTERFACES TRUNK\n

I’ll talk about this in a future lecture,\n

Here is the command to configure the VLANs\nallowed on a trunk.

SWITCHPORT TRUNK ALLOWED VLAN, and then there\nare some options.

WORD allows you to simply configure the list\nof VLANs allowed.

So, I used the command SWITCHPORT TRUNK ALLOWED\n

Notice that the SHOW INTERFACES TRUNK command\n

Now let’s take a look at the ADD option.

This allows you to add allowed VLANs to the\n

Currently VLANs 10 and 30 are allowed, let’s\n

hosts in VLAN20 are connected to SW1.

This time I used the command SWITCHPORT TRUNK\n

The SHOW INTERFACES TRUNK command now shows\n

Note that, because I haven’t actually created\n

displayed in the VLANs allowed and active\n

Next up I’ll show you the ‘remove’ option.

VLAN20 isn’t necessary on this trunk, so\nlet’s remove it.

I used the command SWITCHPORT TRUNK ALLOWED\nVLAN REMOVE 20.

Now, as you can see, VLAN20 has been removed\n

Next up lets look at the ALL option.

I think this one is fairly obvious, but lets\ntake a look anyway.

This time I used the command SWITCHPORT TRUNK\nALLOWED VLAN ALL.

Now all VLANs are allowed on the trunk.

This is the same as the default state, as\n

Next up lets look at the EXCEPT option.

It allows all VLANS except the ones you specify.

I used the command SWITCHPORT TRUNK ALLOWED\n

As you can see it allows all VLANs except\n

Okay, finally let’s look at the NONE option,\n

This time I used the command SWITCHPORT TRUNK\n

This effectively allows no traffic to pass\n

settings we want for this network.

SW1 has hosts in VLAN 10 and VLAN 30 connected\nto it.

No hosts in VLAN20 are connected, so there’s\n

So, let’s set the allowed VLANs to 10 and\n30 like we did before.

Now the only VLANs allowed on the trunk are\nVLANs 10 and 30.

The reason to do this is for security purposes,\n

Also, for network performance purposes, this\n

and such in other VLANs won’t be sent over\nthe trunk.

Now, I said I’d show you how to change the\nnative VLAN.

For security purposes, it is best to change\n

Network security will be explained more in-depth\n

This video is already getting long so I won’t\n

about limiting unnecessary traffic in the\n

Also, remember to make the native VLAN match\nbetween switches.

Now let’s look at how to change the native\nVLAN.

The command to change the native VLAN is SWITCHPORT\n

As you can see, the native VLAN has now been\nchanged to 1001.

After configuring this trunk port, I did the SHOW VLAN BRIEF

Notice that G0/0 is not listed anywhere. Not in VLAN10 or

even though those are the VLANs allowed on the trunk.

This is because the SHOW VLAN BRIEF command shows the access ports

not the trunk ports that allow each VLAN.

Use the SHOW INTERFACES TRUNK command instead to confirm trunk

Now that we’ve seen the configurations\n

On SW2’s G0/0 interface, we must allow VLANs\n10 and 30.

On SW2’s G0/1 interface, however, we must\nallow VLAN 20 as well.

Here are the configurations for SW2’s G0/0\n

These are the same as before, so I won’t go\nthrough each one.

You can pause the video if you want to take a look\n

Now let’s move on to G0/1, which is connected\nto R1.

Okay, here are the configurations.

Almost identical to G0/0, except I allowed\n

Now, both G0/0 and G0/1 are displayed in the\n

So, that’s all for the switch configurations\nfor this lesson.

However, you may be wondering about the router.

In the previous lecture, we used three separate\n

R1, and assigned a separate IP address to\neach one on R1.

Each one served as the default gateway address\n

However, now we are using only one physical\n

So, we must use ‘subinterfaces’ on\nR1.

First of all, look at the title of the slide.

ROUTER ON A STICK, also written as ROAS.

It’s a bit of a strange name, but it’s\n

routing, as there is only a single physical\n

and it looks like a ‘stick’ on the network\ntopology diagram.

So, in this case that one physical interface\n

It’s connected to G0/1 on SW2.

But, we can actually divide this one physical\n

which will allow us to perform inter-VLAN\n

G0/0.10 for VLAN10, G0/0.20 for VLAN20, and\nG0/0.30 for VLAN30.

These three logical subinterfaces are really\n

to SW2’s G0/1 interface, but they can operate\n

Before we look at the router configurations,\n

We already configured G0/1 as a trunk, and\n

That’s all you need to do on the switch, configure\n

Now let’s look at the router configurations.

First, make sure the interface is enabled\n

Next up is the first subinterface.

Notice how to enter subinterface configuration\nmode.

This subinterface number does not have to\nmatch the VLAN number.

However it is highly recommended that they\n

If each subinterface’s number matches the\n

The next command after that is ENCAPSULATION\n

This tells the router to treat any arriving\n

as if they arrived on this sub interface.

If a frame arrives tagged with VLAN10, R1\n

It will also tag all frames leaving this subinterface\n

Finally, after the encapsulation dot1q command,\n

Once again, I have assigned the last usable\n

And that’s all for this subinterface.

Then I did the same thing with the other two\nsubinterfaces.

Again, I made the subinterface and VLAN numbers\n

of each subnet as the IP address of the subinterface.

If you confirm with the SHOW IP INTERFACE\n

subinterfaces appears, as well as the physical\n

itself has no IP address assigned to it.

And here is the routing table.

Notice the connected and local routes are\n

to regular physical interfaces.

When R1 sends frames out of these subinterfaces,\n

For example, if a packet arrives destined\n

the packet out of it’s G0/0 interface tagged\nwith VLAN20.

Okay, let’s review the important points\nabout router on a stick.

ROAS is used to route between multiple VLANs\n

The switch interface is configured as a regular\ntrunk.

The router interface is configured using subinterfaces.

You configure the VLAN tag and IP address\non each subinterface.

The router will behave as if frames arriving\n

subinterface configured with that VLAN tag.

Finally, the router will tag frames sent out\n

Now that we have configured the router, let’s\n

routing works with these subinterfaces.

This PC in VLAN10 is trying to reach this\nPC in VLAN30.

SW2 sends the frame on its G0/1 interface\n

R1 receives it on its G0/0 interface, identifying\n

The destination is in the subnet 192.168.1.128/26,\n

so it sends the frame out of its G0/0 interface.

It tags it as VLAN30 because that is what\n

SW2 then forwards it to SW1, tagging it as\n

SW1 then forwards the frame to the destination.

Okay, let’s quickly review before moving\non to today’s quiz.

I think I say this after every video these\n

Please rewatch certain parts of the video\n

materials to help you practice and review\nas well.

First off, we answered the question WHAT IS\nA TRUNK PORT?

It’s a switch interface that carries traffic\n

We also answered what the purpose of a trunk\nport is.

It allows switches to forward traffic from\n

instead of having to use a separate physical\n

I also introduced 802.1Q encapsulation, which\n

and is used to identify which VLAN the frame\n

I showed how to configure trunk ports on a\n

type, allowed VLANs, and native VLAN.

Finally, I showed you how to configure ROUTER\n

subinterfaces on a single physical interface,\n

VLANs and subnets to be routed without having\n

It’s like a trunk port on a router.

Finally, let’s move on to today’s quiz.

You want to configure SW1 to send VLAN10 frames\n

B, switchport trunk allowed vlan 10.

C, switchport trunk allowed vlan add 10.

D, switchport trunk native vlan 10.

Pause the video to think about your answer.

The answer is D, switchport trunk native VLAN10.

A, encapsulation dot1q 10 is used on a router\n

B and C are used to modify the VLANs allowed\non the trunk.

D is used to specify the native VLAN, and\n

After modifying the VLANs allowed on a trunk\n

A, switchport trunk allowed vlan default.

B, switchport trunk allowed vlan all.

C, switchport trunk allowed vlan none.

Or D, switchport trunk allowed vlan 1 and\n1001 to 1005.

Pause the video to think about your answer.

The answer is B, switchport trunk allowed\nVLAN all.

By default all VLANs are allowed on a trunk\n

will return it to the default state.

Answer D, by the way, lists the VLANs that\n

different than the VLANs allowed on a trunk\nby default.

You try to configure an interface on a Cisco\n

mode trunk, but the command is rejected.

Which command might fix this issue?

B, switchport trunk encapsulation 802.1q.

C, switchport trunk encapsulation dot1q.

Or D, switchport trunk encapsulation auto.

Pause the video to think about your answer.

The answer is C, switchport trunk encapsulation\ndot1q.

On Cisco switches that support both 802.1Q\n

you want to manually configure the interface\n

encapsulation type with SWITCHPORT TRUNK\nENCAPSULATION DOT1Q.

You could use ISL instead, but ISL is almost\nnever used.

Which field of the 802.1Q tag identifies the\n

Pause the video to think about your answer.

VID stands for VLAN ID, it is 12 bits long\n

TPID stands for tag protocol identifier, and\n

PCP stands for priority code point and is\n

D, VLN, is not a real field of the 802.1Q\ntag.

Let’s go to the last question, question\n5.

You configured switchport trunk allowed vlan\n

appear in the Vlans allowed and active in\n

A, VLAN10 doesn’t exist on the switch.

C, the command should be switchport trunk\n

Pause the video to think about your answer.

The answer is A, VLAN10 doesn’t exist on\nthe switch.

If a VLAN doesn’t exist on the switch, even\n

appear in the 'Vlans allowed and active in\n

Okay, so as always there will be supplementary\n

There will be flash cards to use with the\n

There will also be a packet tracer practice\n

That will be in a separate video.

Before finishing this video, I want to think\n

Thank you to Charlsetta, Lito, Yonatan, Mike,\n

Sorry if I pronounced your names incorrectly,\n

Extra shoutout to Boson software, I absolutely\n

network simulator, check out the links in\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.

I'm also a Brave verified publisher and accept\n