Original subtitles

>> I'm so looking forward to this nugget.

And it ties together the concepts of routing which we just talked about with the concept

of VLANs which we just talked about previously.

So, here's the idea.

VLANs are a layer two features, that's really low in the OSI model in terms of things.

So, when they separate something at layer two and the only way that you're going to beat

that is by doing layer one separation and that would look

like taking those two computers there connect to that switch and physically plugging them

into different switches and then you could say, "Okay, see I'm even more separate

than I could be at level-- at layer two because I'm now-- not even on the same switch.

I'm physically separate, physical separation."

So, layer two separation is, I mean, it's really separate, it's as low as you can get

without physically separating your devices.

So, your devices when they are put on different VLANs truly cannot talk.

You know, even if we were to do something like this and let's say the one

on the left we give him 10.1.1.50 as the IP address,

the one on the right in the right is 10.1.1.51.

Even if they're in the same IP subnet and now, you can think of that,

you're okay well that's layer three, that's above the above the VLAN.

Well, it's kind of like layer three, everything works its way down, right?

Layer three is great as long as it has a layer two to stand on.

I mean, what's the first thing that happens when this guy try-- tries to access this guy?

He sends a broadcast, right?

He's saying, "Hello, I'm trying to reach 10.1.1.51.

ARP, what is your MAC address?"

And the ARP goes nowhere.

It comes out the two red ports and there is no 10.1.1.51 on those red ports so, he is cut off.

Even if we manually could type in the MAC address of this guy and somehow associate it.

So, this guy wouldn't have the ARP, the VLANS would still separate it.

It would still say, "No, you cannot go there.

You are not authorized.

This is a layer two separation."

So, we've got these guys that are saying, "Help us.

We can't talk."

So, the host can't speak directly even if they need too.

Even if, you know, the one on the right is, you know, accounting server nine or something

like that the one on the left is accounting user one.

So they need some kind of layer three assistant to make it happen.

Enter stage left, [inaudible], the router.

[Laugh] My weird mind, I was trying figure out a way to have a router come dancing on the scene

and capes and all, it didn't work out.

Now as you saw from the opening slide, I'm going to show you two different options of routing

between VLANs, this one being the first using separate interfaces.

Now, I know it may seem kind of silly but I still remember back

to when I was first learning Cisco when I was looking at CCNA and all I saw was diagrams

like this to where we'll they weren't even that nice.

See, they're just kind of like, you know, in a textbook black and white.

You know, I just saw this logical view of the network.

And while I was like, okay I kind of get it like I never really get it

until I started seeing physically.

I'm looking at the rack, I'm tracing cables and I'm like, oh, oh that's how it's plugged in.

So, I tried to represent what we see in this logical view with what it actually looks

like physically doing this kind of thing.

So let's look at the physical and then we'll jump back over there.

Physically, I have a router this is get old 60 just because clip art guy made the guts.

You know the same, same router we saw previously.

We've got one interface we'll say Fast Ethernet 0/1 plugged in to we'll just say port two.

That's what it looks like, Fa0/1.

Another interface is plugged in to, I'll put F0/0 is plugged in to I don't know it's looks

like about port 10 or something like that that's over there.

Now, these ports as you can see from the logical view are in different VLANs.

So maybe this, this port is a sign to VLAN 10.

And let me switch colors.

This port right here is assigned to VLAN 20.

Now these computers right here, they'll be assigned to the VLANs as well.

Let's go back, go purple, we'll say this one right here connected port 12 is assigned

to VLAN 10.

And the computer on the right, this one-- now don't you love--

I've tried to find that old sputnik kind of computer that I could.

The computer on the right, he's going to be in the VLAN 20.

So, these ports right are assigned to the appropriate VLANs, right?

So, what that means is this guy, if we are to follow his packet flow,

we would go into this interface we'll say, "Fast Ethernet 0/-- let me write in the red F0/0."

He'll be assigned an IP address from this guy's subnet.

So we'll make him 10.1.20.1.

This guy over here, this computer might be 10.1.20.20 and this is his IP address.

And he has a default gateway, well what is default gateway be?

10.1.20.1, right?

So, what that saying is, he-- and these are all /24, so a Class C subnet mask.

So, to get off of his network he's going to come in here ARP for his default gateway

which is on the same VLAN come in here.

This guy, let's say he's trying to ping the purple guys.

Let's fill in the purple players.

Purple guy number one is 10.1.10.20.

Let's give him that IP address.

His default gateway is 10.1.10.1 and that's his port right here 10.1.10.1 is the IP address

we'll assign to this interface.

So, when this guy, when the guy on the right pings the guy

on the left his packet flow is going to go wooh, you know, coming in down here, hit this guy,

he's going to look at his routing table and go, "Oh, great you're right over there."

He's going to come in to this port on the switch of VLAN and then come out and reach this guy.

By the way, you'll often see routers that are connected this way.

And actually, the way I'm showing you right now is very, very uncommon.

It's just kind of to learn the concept.

I'll show you the most common way, coming up.

The commonly called routers that are connected like this a router on a stick.

I kid you not like a corn dog or something.

You know it's a-- yeah, Google it, and you type in router on a Stick

and you'll see this exact diagram.

So, from a logical view, this is kind of what it looks like.

So that's physically, this is what it looks like from the logical view, two computers,

two different VLANs, router one interface in each one of those VLANs.

Now what I just did was pause the recording so I could go in

and label all of the different ports.

Now, forgive me I did-- just to how I put things in.

The ports physically on this view I don't reflect the actual orders.

So, this is my computer that's what I'm working on right now plugged in to Fast Ethernet0/5.

This is my Dell laptop.

I actually have a little tiny laptop I used to test and play around with.

I've got that plugged in to Fast Ethernet 0/6.

Now I'm already going in but actually when I paused it I went in

and assigned these guys the correct IP address.

So you can see these guys got 10.1.20.50.

And well, you can't see the laptop but it's got 10.1.10.50 [inaudible] there we go.

So, it's got the 10.1.10.50 [inaudible] me and this is this is my laptop.

So, they each have their default gateway set to 10.1.20.1.

And this guy has his default gateway set to 10.1.10.1 which is going

to be how we configure this router.

Now this router you can see is plugged in to Fast Ethernet 0/3 and 4.

So, the first thing I haven't even done any of this config 'cause I want

to show it all to you on the switch.

All I did was going in and I kind of turned on the ports 'cause they were all shutdown.

So, let's go in and create first off the two VLANs on CBT switch.

Let's do a quick show VLAN first.

This is from-- we still have some VLANs hanging around from the previous Nugget that we did

and that's fine they're not going to causing any harm there's no ports assigned to them.

So, I'll go VLAN 10 named blue exit, VLAN 20 named red exit.

Okay, so we've got the two VLANS created let's go start assigning some ports.

I'm going to go into interface Fast Ethernet 0/5.

Just to make sure, switch port mode access that should all be that way but

and I was-- I want to double check.

Then we will do a switch port access VLAN.

And we are in the red so that'll be VLAN 20.

Hit the up arrow and that's shoot over to Fast Ethernet 0/4.

Yet, there's some other ports that are red

but they're just logical and not assigned to any thing.

So, you are VLAN 20.

And if you were being thorough you could do a description

and put router VLAN 20 interface and so on and so forth.

We don't need to do that though.

So, I exit back out and let's go into interface Fast Ethernet 0/3 through him on VLAN 10 as well

as Fast Ethernet 0/6 which is the PC put him on VLAN 10 as well.

Okay, good.

So, let's go back in to a show-- show VLAN.

I saw my VLAN once.

See how these messages are valuable.

VLAN one just went down.

Why? Because there's no active ports left

in VLAN one I just moved all the active ports out into these other VLANs.

So now I have VLAN blue and VLAN red with the correct ports assigned that kind of match

that diagram that you see on the screen.

Now I'll do a show IP interface brief.

These are these are the four ports right here that they're all plugged in to.

So we're kind of seeing in the config what's reflected there on the diagram.

Okay. Now what?

Now I need to go over to the router.

So I've got the VLANs setup, everybody is separated even if I wanted

to at this point my happy computer could not reach

over here 'cause they are not only different IP subnets but they are

on completely different VLAN, so they're not talking.

So I'm now going to go to my router and give this guy the IP Address.

So, on the blue VLAN, he'll be 10.1.10.1 let's add those in there.

On the red VLAN, he will be 10.1.20.1, right?

So this guy is going to kind a do this, this sort of thing

and then loop back here to communicate with him.

So, that's going to be the flow of the chain of events.

On the red VLAN, he will be 10.1.1.20.1, right?

So this guy is going to kind of do this, this sort of thing

and then loop back here to communicate with him.

So, that's going to be the flow of the chain of events.

So, let me keep those and then let's jump over the router.

Reach down, move my console cable up.

Sometimes I'm-- sometimes I'm glad there's no camera to show just how wacky it was set

up this-- 'cause I've got-- I like standing when I teach

but I don't have a standing desk anymore.

So I literally have packing boxes where I put my keyboard up, my-- like it's funny.

So, and now, I moved over to the router.

So, show IP interface brief.

Now this, we just did the base config in the last nugget,

so we just I think demonstrate putting an IP address on there but that's no longer relevant.

So let's go into interface Fast Ethernet, interface Fast Ethernet 0/0.

And let's give it the IP address IP 10.1.10.1, 255.255.255.0, enter.

Oh, what am I doing?

IP space address.

So, that's now accurate to meet this.

I'm looking, double checking, Fast Ethernet 0.0.10.1.1.

We're good.

Good. Let's go into interface Fast Ethernet 0/1.

We'll do IP address 10.1.20.1, right?

Put that in there.

Every-- and then they were both powered up just

from the base configuration Nugget that we did before.

So, that's good.

Good, good.

So in this one, let me do a show IP interface brief.

And I see 10.1.10.1.

It's good, looks up 10.1.20.1.

Okay, so let's test it.

I'm going to see if this guy can actually ping 10.1.20.1.

They should be on the same VLAN.

So, well, let's-- let me bring it up.

Ping 10-- well let me just IP config first.

IP config and you know I want to get this-- let me get that guy out of there, there.

You are disabled.

And just-- and this-- that's going to cause confusion I think.

So, LAN1 is gone 'cause we won't know which default gateway

to use since you had two of them.

So, now we just have the LAN2.

Okay. So, we've got 10.1.20.50 so let's see if we can ping 10.1.20.1.

And look at that, over there.

And then now, great.

I've severed my network connections I'm getting all these errors.

So, great, where there-- but it's kind of like, well wait a sec,

prove to me that that's the actual Cisco router let's telnet there.

10.1.20.1, this-- I'd never even realized a mistake that-- this a secure Cisco router.

So we're in there, enable Cisco.

So this is indeed the same exact Cisco router.

So, that proves to me now that I can move from this computer into this interface.

Now, my laptop I can't really show you 'cause it's right there.

But that I've already configured with this IP address so let's see if we can ping that far.

Exit out of here and let's do ping 10.1.-- well, first let's ping 10.1.10.1.

That's good.

Okay, what that proves is I'm going out here, hit in this and then I'm able to reach this side

and that tells me the interface is up.

I haven't really gone too much further but let's now go the rest of the way 10.1.10.50.

Okay, there we go.

So, we've got 10.1.10.50 which now replies which tells me, "I'm going through this router,

back out this interface and then hitting this guy."

Now, we can actually prove it a little differently.

I can do trace route, trace rt in the windows world.

Trace route-D, that says, "Don't try to resolve host."

And otherwise, this command just takes forever

because it's always trying to figure out what name is that.

It'll look at the IP address you typed in and trying do what's call the reverse DNS to try

and figure out what host name that is.

Well I do that, it takes too long.

So I'll do trace route 10.1.10.50 which is saying, "Show me the path to that laptop."

And what this shows is my computer which is it's this happy computer over on the left.

My computer 10.1.20.50 goes through the router at 10.1.20.1.

So we're routing now and the router spits it out here and that's

when it ends up reaching 10.1.50.

Now, a trace route if this is your first time seeing it,

it actually does three pings for each hop.

That allows you to see if there's ever a slow link in the chain.

You'll be able to be like, oh, looks like this one is really slow.

But in this case, it's verified for us the actual path that we're going through the router.

Now, let's look at option two.

Most people don't use the scenario I just gave you other than maybe to learn how to route

and things like that because it's just inefficient.

The more VLANs you have and people have lots of VLANs you know 10, 20, 30 that kind of thing.

The more VLANs that you have the more interfaces it's going to end up taking on a router.

And routers honestly don't have that mini Ethernet interfaces.

Usually routers will have, you know, a few maybe two, three, four,

five at most, but routers are also expensive.

So the more interface users start adding in there you just start maxing out the route.

It's just, just inefficient.

In the end, you're eating up extra switch ports for that.

And I mean, if every single router connection needs a switch port then--

or every single VLAN needs a switch port you're eating up just a lot

of your ports just to connect to the router.

So, you probably have been staring at this picture for a second.

What do we do?

We use a trunk port.

Now, remind me again, scream in out loud and people think you're crazy.

What VLANs are carried by a trunk port?

And we all scream, "All of them.

All VLANs are carried by a trunk port."

Absolutely.

So if a trunk carries all VLANs then nothing is to stop us from setting up this router

and connecting it to a trunk port.

So, all the VLANs that's all the blue traffic, all the red traffic that are needed come

down here to this router and it's able to do the routing.

Okay. So, what's that mean to me what-- so, let's go back to the scenario.

We have at this computer 10.1.20.50, right?

And then, this computer 10.1.20.50 or wait a second, 10.1.10.50.

Okay, so we have these IP addresses.

So, if that's the case, then I mean, these guys needed default gateway on their network, right?

One needs 10.1.10.1 the other needs 10.1.20.1.

So now, we're just plugged into one interface here.

So what IP address do we give that interface?

Well the answer is actually both of them.

Let me introduce to you to the concept of subinterfaces.

Oh, that's a weird one.

So, here's-- we've got and we'll say, "Fast Ethernet 0/0?

Now, right now I want to know.

What-- I think yeah this is definitely Fast Ethernet 0/0.

So physically, a Fast Ethernet 0/0 plugged into the Fast Ethernet 0/2.

That interface is the physical interface it actually gets nothing assigned to it.

There's no IP address at all.

What we'll do though is create Fast Ethernet 0/0.10 for VLAN 10.

We'll create Fast Ethernet 0/0.20 for VLAN 20

and then we can give them the IP addresses 10.1.20.1 gets assigned

to that subinterface 10.1.10.1 gets assigned to that one.

So what are those?

How-- I mean, how did those work?

They are virtual interfaces.

We're going to get use to this word virtual, right?

They don't really exist but what it does is accept tags.

Remember, did I say remember?

Remember, the trunk port keeps the tag on the interface.

So, when this guy says, "I need to reach my default gateway."

The trunk port will say, "Okay, this is request from we'll just say client one" and I'm going

to put the tag of VLAN 10 on there.

So when it's received on here, this router will need

to know okay VLAN 10 tags all go this subinterface.

So, that one will respond to it.

And this one, you know, it'll come in and it'll be tagged and we got to go red.

It will be tagged VLAN 20 right there so we need to configure this subinterface to respond

to those tags for VLAN 20, just try it out.

I still have the same configuration on there so let's first off empty it

to where it's back the way it should be for this kind of config.

I'm going to go in to Fast Ethernet 0/1 and do no IP address and shut it down.

We'll not going to need it anymore because we're going

to just connect Fast Ethernet 0/0 to the trunk port.

Likewise, I'm going back out and go

into interface Fast Ethernet 0/0 and do no IP address.

Because like I said, there's not going to be anything assigned

to that individual interface the physical interface.

I'm going to start creating the subinterfaces.

So, let's look at it.

I'll do a show IP interface brief and it feels like we've taken a step backwards in our config

because now it's like there's nothing there.

Well, before I do the router config, I'm going to hop down and do the tru--

do the switch because the switch needs to know that I'm going to set up the port going

to the router as a trunk nor or view, right?

So I'm in CBT switch, I'm looking here on the diagram this is Fast Ethernet 0/2.

We'll do switch port trunk encapsulation dot1q turn on 802.1q protocol

and then I'll do a switch port mode trunk.

That's it.

And it-- oh, wait a sec.

Did I write down the wrong port?

I did, that's why CDP is so valuable.

This-- sorry scratch that it should be Fast Ethernet 0/3.

Great, more practice.

And so, we'll get back in there.

Config T interface Fast Ethernet 0/3.

Switch port trunk and encapsulation.1q.

Switch port mode trunk.

There we go.

That now, we're good.

Okay, so it's saying, "Okay, wait a sec, I'm resetting that interface, change down back up.

So now it's configured as a trunk port.

And remind me to show you a command about trunking, just thought of.

I'll show you that in a second.

I can hear you.

I know what you're thinking.

All right.

So I'm sitting on-- I'm sitting on the router.

I'm going to do-- okay, so here's the subinterface.

I'm going to go into interface Fast Ethernet 0/0.

And you might be wondering.

Well, I mean how many of these can you create?

How many subinterfaces are supported by CSCO?

There it is.

That was somewhere around 4,294, 967, 000 [inaudible].

I mean it's-- no, no, no, no don't go and create

that many sub interfaces I'm sure the router would explode before then.

He's just saying, "You have the flexibility to create a lot of them."

There's no feasible limit to the number that you can create.

But the nice thing about this is you can use whatever, you know, normal number you want to.

So, I'm going to come in here and let me say, "Fast Ethernet 0/0.10.

Now, to make this happen, first off the subinterface number does not--

does not mean that this now magically responds to things for VLAN 10.

The subinterface number is just unidentified.

Let me do a show IP interface brief and you see new magic interface has popped up out

of nowhere this .10 which it doesn't do anything until I typed in encapsulation dot 1q

and follow it up with what VLAN it responds to.

That's the key.

That's the one that says, "Okay, subinterface 0/0.10 any packets that you see tagged

with the number 10 on it remember 'cause this is a trunk that's a good thing.

Any thing that you see tagged with VLAN 10 you will grab, you grab those."

And that's such required command.

So you could and I don't know why you would, you could make this subinterface number 1,292

and then say encapsulation.1q10 and it would do the same thing.

But why would you do that?

It's just not logical.

So, usually, usually, you will match the subinterface number to the VLAN number.

Now, let's give it the IP address.

[ Pause ]

Good. Now, let me show you something else.

I'm going to do interface.

Usually, one thing you'll find in Cisco is that it doesn't really matter what order you typed

to commands in like if I go in and do a no shut first

and then assign the IP address that's fine.

I could also go in and do the IP address and then do a no show.

I mean, the order it's not really order dependent but some commands will.

Like watch this.

I'll do, let me just set the up arrow.

IP address 10.0.20.1, watch what it tells me.

It's like sorry you can't give this subinterface an IP address

until you tell me what VLAN it belongs to.

And if you think about it make sense that the router is trying to convey you it's like, "Hey,

I don't know when to use this subinterface."

There's nothing telling me when this subinterface should jump in

and be like I got you, you know, and grab the packet so.

So, we have to tell it, "Okay, okay, sorry about that."

Encapsulation, and so you're going to grab the packet when it is VLAN 20 and now I hit the

up arrow, takes the IP address no problem, right?

So, now I can do a show IP interface brief.

That's looking cool.

So we've got now the two sub interfaces 10.1.10.1 and 10.1.20.1.

Every thing else is the same and now our computers can do their pings just

with out any problem.

Well, with out any problem.

I actually went in and disable it 'cause I had to save the last recording and it blew up.

So now, let me flip it back it over.

So now I've got LAN2 we should.

We should have-- we should have-- yep, there we go the IP address.

So, let's if it works.

Ping 10.1.10.1.

Dot 10-- Oh, wait no, or scratch that 10.1.20.1, that's the IP address I'm in.

Destination host, oh, there yo go.

Oh, okay, okay.

Thank you Window 7.

See Window 7, it fix you out like Windows XP, when you disable and enable an interface

like that, it'll just hang there.

It's like I'm just sitting here and you're like what's wrong with you Windows and as fell

as I go gamed on like 30 seconds later.

Window 7 is like ha, ha I'm so fast

but really behind the scenes it takes with the same 30 seconds.

It's just doesn't make it and he sent it away.

So, it just took some time and there we go.

We now have my interface, my interface active.

And now, what I'm doing is I'm coming in over that trunk port.

Let's do a show interface Fast Ethernet 0/0.10.

That didn't show me too much.

So, well, I guess we'll only see the statistics on the parent interface.

So I can see-- you know, this guy is not much but he's receiving some data for these

and now I should be able to ping through to the other side.

So, the same exact result 10.50, right?

Ping 10.1.10.50, there we go.

Same exact results as before.

However, this one using-- this is truly a router

on a stick this one using the trunk configuration to do this.

Now, let me mention one more thing.

I'm really debating, adding a third option in here and I think I'm going to.

I want to mention one more thing and that is the validity of router on a stick.

You will find a way, if you get in the real world and some one is like,

"Hey, did-- so I heard you took CCNA?

Did you learn routing through VLANs, you know."

"Like, oh yeah, using the router on the stick" and they'll be like, wa-ha-ha, nobody,

uses router on a stick blah, blah, blah."

You know it's like they have this thing-- I will say router on a stick is designed typically

for smaller environments, but it is used all of the time.

And you know, the reason they say people don't use it is because it's a bottleneck

and that that is absolutely correct.

Because literally, for this guy to get to this guy, he's got to go do this little thing.

Da, da, da, da kind of you know, hopping back and forth that's the--

that word yo-yo effect you get on the, the router on a stick because you're going out

and back in, in and out and back in.

You're going-- and see that kind of thing.

So, it will slow you down but I'm telling you for small,

sometimes even maybe mid-sized business, it works great.

I mean if you can't afford a layer three switch which is option number three,

there's no replacing a router on a stick.

All right.

So, let me show you-- oh, oh, oh wait, wait, before I do that before I see--

I almost forgot somebody who reminded me.

I heard him, I wanted to show you one more command on trunking.

Well it's kind of a nice one.

We've configured a number of trunk interfaces now, right?

On our CBT switch, there is a quick command that you can use

to show what interfaces are trunking.

You can do a show interface trunk.

This is handy because I can go in there and I can say, "Oh well, now,

there are more trunks but they're not active."

I can see Fast Ethernet 0/3 it's on 802.1q is its encapsulation and it says, "Okay,

VLANs allowed or all of them as it"-- now, we can restrict it, we can go in and say, "Well,

not that VLAN, not this VLAN, not that."

You know we can trim it down.

But it's saying normally a trunk allows all VLANs so everything is allowed

and then these are the ones that are actually active.

So, even though on this example we only use VLAN 10 and 20 to switch

because it is a trunk is allowing me to send all these VLANs to the router.

So, all that traffic is going to the router.

Now you might say, "Oh, wait a second, that doesn't feel efficient.

Can I trim that down?

Can I like-- can I just say VLANs 10 and 20 are allowed to cross that trunk to the router?"

Answer is, "Sure."

Go into interface Fast Ethernet 0/3 and you can do a switch port trunk

and the command is actually allowed.

Do you see that?

Allowed VLANs and you can say, "I want to allow all of them.

Well, I want to allow a few of them, add a few of VLANs to them

or I want to remove the current ones.

Now, you've got to be careful because you might say, "Okay, allowed VLAN 10."

And I won't allow it ''cause it's, you know, it just says word that's why it hit VLAN 10.

And says, "Okay, what I'm going to do is now trim that down you can see that kind of takes

down a VLAN one 'cause nothing else is active there now.

So, I'm going to do a show interface trunk again.

Now you can see the out port and it says, "Allowed VLANs are active now."

You've got to be careful here, be very careful.

In production, it's very bad to just cut off VLANs on a whim

and it's sometimes you'll be like, "Okay, well I want to do--

okay, I've added 10 let's add 20 now."

I will tell you, everybody makes that mistake once.

It's like the matrix, right?

Everybody falls the first time Neo.

That can be a painful fall because what that does is and let me go back,

is notice it just replaced VLAN 10.

So, let me talk to you about a production environment.

You've got switches, you know, they're doing their thing with trunking and you've got all

of these hundreds of devices connected, you know, 50 different VLANs.

You know like oh, I just need to add VLAN 50 here.

So you go in and type the command that I just showed you and say, "You know, allowed VLAN 50"

and what happens is all the other 50 VLANs or 20 VLANs or whatever that around

that thing get stripped and replaced by just to VLAN 50.

If you've got some experience in this field, and you done that, you know that pain.

That's a complete outage, and that a few phone calls and that's sent

down in the manager's office saying, now why did you do that again?

So you got to be careful, this is a replace command.

So, if you want to use the switch for trunk-allowed VLAN,

then I will do 10 comma 20 that will do that.

Now, what if you've got a whole bunch of VLANs, you don't want to retype them all, right?

So what you can do is that-- let me go back and let's just say,

allowed VLAN 10 so we're back down to just 10, right?

And so now, I'm going-- let say, I want to add in 20, so I can do switch

for trunk-allowed VLAN add, you know, instead of just typing in VLAN I'm saying,

add to the current list of VLANs that are there VLAN 20.

And that trims it down, and that's pretty cool, because that allows you to be really efficient

to only send the VLANs towards the router that belong there.

Now, one of the things that you'll notice is it says, VLANs allowed, VLANs active,

VLANs forwarding and not pruned only 10 it takes some time, it takes usually 5 to 10 seconds

for the VLANs to come up once you've added them in there, maybe 30 seconds.

It just takes time now before the VLANS are actually added to the trunk, but if I stand here

and there we go, and hit the [inaudible] enough times it will pop, and pop in there,

so that's the one that I want to show you.

Now, let me talk about option number 3.

I wasn't originally going to show this, but it's so valuable and it's

so easy that I've just got to do it.

Option number 3 is essentially that.

There is no router, or I guess more specifically there's no external router.

Option number 3 is what just about every large network will use and that is setting

up a system of layer three switching.

Now the 3550 happens to be a layer 3 switch,

and what that does is really integrate routing inside of the switching device.

So instead of needing a router outside here which you run into environments where you have

to have that, but they actually include routing capabilities and the way that we do it is

through those VLAN interfaces that we were setting up way back in the VLANs.

Remember I said, when you create VLAN 10, you're actually creating the layer two VLAN.

That was the command where we went in-- we run the switch.

We go into global config and we type in VLAN 10 that creates the layer two VLAN.

But then I said, okay, but what if you wanted a routed interface

for that VLAN or a logical interface?

We can do interface VLAN 10, and that will create an interface

that everybody in VLAN 10 can reach.

Now check this out.

I can give an IP address to that interface 10.1.10.1 the same IP address we were using

for that now that phantom router here as a default gateway, so here's the concept.

Instead of this guy ARP-ing and finding this outside router that will do the routing for it.

He will send an ARP and he'll find, you know, think of it like back here somewhere.

You know, he'll find the router inside of the switch which responds to the ARP messages

and he goes oh yeah, I'll take care of you, I'll switch you between the VLANs.

I'll get you off the-- your VLAN that's no problem.

And so we create that and we go in,

we create interface VLAN 20 give it the IP address 10.1.20.1,

the same IP address-- wait a second.

I keep flipping those.

The same IP address this guy was using as his default gateway, so that the other one is

that guy using his default gateway.

So let me show you "oh."

Let me show you.

I'm going to go into global config mode, so I created VLAN 10.

VLAN 10 has always been there.

Now, I'm going type in Interface VLAN 10, IP address 10.1.10.1, Interface VLAN-- "ops."

Let me unplug that router which is saying, I've got that IP address, what are do you doing?

He's gone.

So IP address interface VLAN 20, IP address 10.1.20.1, 255.255.255.0, okay?

So now we've got, and I'm wondering why did VLAN 20--

oh, because there's nothing active in VLAN 20, because I disabled my network card.

So let's bring him backup.

We should see VLAN 20 resurrected itself.

So now, let's go back.

And I see that we've got VLAN 10 which is no-- we've got VLAN 1 as well.

So this guy is like, got arms every direction.

VLAN 1 was what we did when we put the base configuration.

VLAN 10 took the 1 IP address of the router.

VLAN 20 took the other IP address.

Now that VLAN 20 is going to come up any second to where that's now active,

but now I'm able to on my computer and this is something I want to do.

There's VLAN 20 just when active down there.

I'm going to do first often ARP-a.

I want to make sure.

Let just make sure 10.1.20.1.

I don't-- see, here's the problem.

My computer remembers the IP address-- sorry the IP address to Mac address mapping for 5 minutes.

So I'm going to clear the ARP table.

ARP-D star as a command.

That actually wipes out the whole ARP Table.

So the next time I try to ping, it's going to make sure I'm checking the Mac address

because previously, that duplicate Mac address thing alerted me to that.

Previously, this guy had the IP addresses and he had a different Mac address than the switch.

So if this guy remembers his Mac address he's not even going to send out the ARP for minutes,

and we're going to not be able to communicate so, let's jump back there.

So now, I'm going to get on my command prompt

and let's do a ping 10.1.20.1 is the IP address of the now the switch.

It's not replying which is great.

And I can ping through now, ping.10.1.10.1.

I hope-- actually, you know what?

Probably not going to be able ping to through, because I have--

this is an annoying thing-- all right there we go.

It's now back in place.

There we go.

As soon as I did that, it's like, now I can.

Now I've only got one-- one interface to default gateway, so now I'm pinging through.

And you notice that, both of the IP addresses are own by.

Oop, I forgot that we put a username on that what was it?

Germany, there we go.

They're owned now by the CBT switch, the router is out of the picture, in large network.

In, you know what, layer 3 switches are no longer a out of reach commodity.

The price has come down on them significantly and recently here so.

This is really starting to take hold then we're trying to see a lot of layer

through switches all over the place.

That's your option 3.

That's the one that businesses normally use.

The biggest advantage of using a layer 3 switch is the speed,

because as soon as you get a layer 3 switch that has the--

man I thought I can do it right while I'm talking, nope.

Layer 3 switch.

The layers 3 switch that-- or a switch.

Okay, I'm done writing.

Switch as the layer 3 capabilities will have A6 to support it.

So a layer3 switch will always be faster than the router because it can actually route

at wider speed, that's the biggest advantage.

In addition to all of the other ones to where you don't have to have an extra router,

you don't have tie up a [inaudible], you don't have configure trunk, you don't have bottleneck.

I mean there's just so many advantages to using a layer 3 switch.

So that is kind of your intense jump into the water of routing.

We went from what is a router to routing between VLANs tying together all those concepts.

We saw, using separate interfaces which, not a recommended method anymore, although it works.

Using sub interfaces by connecting a router interface to a trunk port and then number 3

by using no router at all, by using a layer 3 switch,

and using all the internal logical interfaces inside of there we can move our data,

we can route our data between VLANs.

I hope this has been informative for you, and I'd like to thank you for viewing.