Two vs Three-Tier Network Architecture: Remove Single Points of Failure

hey i've got a question for you can your network survive a pug

okay what about a baby if it can't if you can't afford to lose one link or one switch or one router

you're doing it wrong in this video i'm going to show you two network architectures that can help make

our networks awesome and a huge massive shout out to boson software they are the official

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boson has the best labs practice exams and now the best courseware you can find for the ccna i'm actually giving away

three copies of their courseware and labs in the link below so enter that contest it ends

tomorrow friday so hurry up now before i show you what a good network design looks like just a

beautiful delicious one let me show you a bad one first as you're working towards becoming a

network engineer you're gonna see some bad networks and it's your job to identify why they're

bad and how you can make it good now to find a bad network you don't have to look very far

look in your house i'm not kidding your home network sucks no i know a lot of you probably have an

amazing home networking comment below with what you have but for a lot of you if you ran a business out

of your house and you use that home network it just die your business would be dead now i say that

because a lot of businesses when they first start out their network looks very similar to a

home network and they make some big boo-boos some very big mistakes let me show you what it might look like

so network chuck coffee still a very young small growing coffee company and let's say i

trusted a noob to install my network i would never do that but let's say i did very similar to your home network

i'll have a router although in your home network your router isn't just your router it's also

your switch your modem even your web no not the song a wireless access point this is a

networking video get your head straight so it's doing a lot which is a horrible thing uh

you don't want to have one device doing everything and we'll get into why that's important here in a moment but for now

my coffee company just has the router and my router connects to a switch and honestly for a small business this

is fine i've got my computers connected to my switch i'll have a wap the wireless access

point connected to it as well giving me wi-fi to all my people maybe a few phones and then of course my

server to run my website well hold on a second my switch only has 24 ports i'm out of ports i have more things to

connect more computers more servers what do i do when i tell my new network engineer to fix it for me

this is where the noob really screws up what does he do well he gets another switch it's fine he does a great job

getting that here it comes and then he connects the switch to the switch and then oh

hold on what did you do what did you do this is bad i'll explain why here in a moment and before long i'm growing i'm

going like crazy so i need to add another switch so my new network engineer does another another

switch and he adds it out here and and then he does it again he connects the switch to that

switch i'm sure a lot of you if you know networking that's probably scaring you

it makes me just have heart palpitations just thinking about it this is bad

now it works don't get me wrong this totally works but then this happens my pug moses comes over and starts

chewing on this cable right here then suddenly the cable breaks and then what happens

well all the device is connected to the switch and this switch they gone they can't connect to anything

right they're down this right here is what we call now say it with me a single point of

failure don't ever have those in your network ever all of these right here are single

points of failure which basically means if one thing fails then most of your stuff goes down

never want to have that now again this design still works you might have something like this in your house

there are a lot of businesses that have this and it works most of the time until something fails in your home you can

afford it to fail because the worst thing that can happen is you miss an episode of netflix

or worse you can't watch my next video whatever but in business that means dollars and

cents that's money time now i'm showing you this because you will see this in the wild in the real world

and you have to tell them why it's dumb and you have to fix it so how do we fix this what do we do well

some might think well you know we have those single points of failure let's just add another connection we

could do that add another cable here another cable here that's better but what if the

switch goes down where this switch goes down we still have glaring problems and this is not

ideal which is why we have two designs we're going to talk about today it'll help us become redundant and

you'll hear that word a lot when you're talking about network design you want to remove as many single points

of failure as you can so you want to be able to have a cable go down but things still be up

a switch goes down but things still be up let me show you what that looks like so daisy chaining our switches together

bad don't do that so what do we do how can we make this better well we could do this watch let's put

the router right here and instead of daisy chaining we just connect our switches to the router each one done

that was easy come on chuck you're making it sound so hard well we're not quite done now this will

work but it's not ideal so for example my computers this works great for when they want to

get to the internet because that's what the router is great for layer three but my computers and my

servers aren't just talking to the internet they're talking to each other they're

talking on the same network and that's where the router becomes less ideal and he's not the best

guy for the job so what we want is another switch but not just any switch oh you're gonna

love this this is something when i found this out i'm like

mind blown so we're gonna scooch the router up here for a moment he's still in play but we're gonna

talk about something else here we're gonna bring in this guy right here what is that it's a switch but it's not

just any switch this my friends is a multi-layer switch often referred to as a layer 3 switch

which might sound weird if you've watched my previous videos we know that switches

they deal with layer 2 mac addresses and routers deal with layer 3

ip addresses what's a layer 3 switch doing here that's sci-fi that's weird i can't deal with that

no it's amazing it's literally a switch that can deal with ip addresses and mac addresses

it can do it all and it's blazing fast and then our multi-layer switch will connect to our router and

we're looking a bit better right now aren't we i mean it's really beautiful if this

connection goes down or this switch goes down then these two are still up this computer's

still up this server's still up it's better right and i'm sure you're thinking well chuck we still have this

right here this single point of failure yeah we'll get to that we're taking baby steps and you'll encounter this a lot

when you design networks for businesses because designing a network with limited single

points of failure can be crazy expensive the more devices you add the more the bill goes up so i'll show you how we can

fix this single point of failure here in a moment but just know the more we add the more it costs you'll

have to work with the business and what their budget is now this architecture this model here

the way we designed our network is called a two-tier architecture let me show you the tiers

right now here's tier number one and tier number two the switches in this tier one are called our access

switches and we'll we'll call this layer our access layer because they give our devices the

things we connect to our switches you know my cables go hold on things like raspberry pi's giving them

access ooh that sound let me add a pie in there real quick can't not have a pie raspberry pie in my

network here what am i crazy there we go much better and then our tier

two layer this guy is called our distribution layer and of course this would be our distribution switch

why is he called that well because his job is to distribute all the packets all the frames throughout the network

like he's it everything goes through him if the computer wants to talk to my server the computer goes

access switch distribution switch down to access switch down to server if he wants to access the

internet access switch distribution switch router now because everything goes

through him he's got to be pretty bulky he's gotta be he's gotta be big now what do i mean by that well think

about computers this raspberry pi while he's awesome he's not like a computing powerhouse

he's tiny you're not gonna be playing call of duty on this guy well not yet we you never know he's not powerful enough

and the same goes with switches if he got a tiny little eight port switch he can only handle so much traffic

before he's like i need help so don't put a tiny little eight port switch and your distribution layer he'll

die so in the distribution layer you'll want a massive switch with a lot of

horsepower and just like a computer it'll have more components more expensive hardware to

make it faster now i've shown you access layer switches it's something like this

but distribution layer switches are a whole other beast emphasis on beast let me show you one

real quick here are a list of cisco switches that could be considered distribution layer switches and you

you've got options and all depends on what you need and really how much you can spend so like right here we have the

cisco catalyst 3850s they have a very similar form factor to the axis layer switches but they can handle a lot

more like look here 480 gigabits per second on their back plane which means they can handle that

much traffic going through them at once which is a lot but of course if you need more you can

get more you go to the cisco catalyst 6500 you got 11.4 terabytes per second

or terabits per second and look at that thing that's crazy look look at that guy and we'll cover more

about these guys here in a moment because they can go bigger and they have a different role

we'll touch on that here in a moment now we haven't gone too deep down the cisco rabbit hole just yet we will don't worry

so i kind of glossed over what the distribution layer is responsible for it does more than

just distribute like let's take a field trip over to the boson courseware real quick

you'll want to get this stuff i've got their courseware open now let's learn about the distribution here real quick

if you want to get this i got a link below now i didn't mention this before but the distribution layer is sometimes

referred to as the aggregation layer let me highlight that that's the worst highlighter ever better

okay but it does things like route filtering enter vlan routing management acls ips security policies

routing because remember they are layer 3 and then summarization and next hop redundancy

i said a lot of words that we have not covered yet we will just know that those are the roles that the distribution

layer typically has or the ones we give it give to it now there is something i

skipped over you may have noticed this because the distribution layer is the intermediary between the axis layer and

the core layer what's the core layer i didn't talk about the core layer

well hmm if i scroll up just a little bit look at this there's another layer what what is that

we'll talk about that right now we're only looking at the distribution layer and axis layer

which is called the two-tier architecture and we'll again we'll touch on it here

in a moment now let's talk about these other single points of failure how can we fix

things well we can add more devices right like check this out i can add one more distribution layer switch

let me do that scoot him over right here and we'll connect our switches so it might look like this

we'll add one more connection one more connection one more connection then of course we'll connect our switch

to the router and then we even connect our two switches to each other this is what

i'm talking about we've got two distribution layer switches no longer a single point of failure we've got two

links to each switch that's amazing and then we have two connections to our router but wait hold

on we still have one router we can solve that let's solve that right now let's

put in one more router and we'll connect both switches to them man look at all that redundancy it's

beautiful but it's expensive this is ideal a lot of companies aren't willing to

pay that much for stuff because these i mean oh my gosh these layer three switches

they could be like hundreds of thousands of dollars same for the routers depending on how big you go no one said

networking is cheap which is why we make the big bucks now this two-tier architecture isn't the

only kid on the block and let me show you where a three-tier architecture might come into play

let's say network shut coffee really just starts booming like oh my gosh and we have to add more

buildings just to hold all our people we have so many people now now we have three buildings things are

booming it's amazing but we need to connect our buildings together so we can all you know

have a network that's what we're doing here right all right let's connect them so i'll connect my multi-layer switch to

my multi-layer switch down here my distribution layer same thing let's go over here and let's

do it right here just random but hey we got connectivity right but let's make sure we add in some

redundancy we'll also add redundant links make sure each switch has a connection

to each switch and each location has a connection each location okay we did it it's kind of a

mess but we did it ah we have another building coming in okay get ready guys i gotta hire some

more network engineers all right so let's connect them here we go okay this is getting a little crazy as

big as our distribution switches are they're under fire right now they can't handle all this stuff too many

connections they're running out of ports we're maxing out the bandwidth what do we do

let's go with a three-tier architecture you saw that coming right let's do it get all those connections out of there

whoo stressing me out we're going to add one more layer here so let's get our routers out of here

or scoot it up we're not going to get rid of them and we'll put our next layer in and this layer will have a

beast of a switch it will also be a layer 3 switch but this will be the big daddy

he'll be so powerful so awesome he can handle all that traffic this switch is our core switch and this

is our core layer tier 3. our distribution layer switches will connect up to him

in a perfect world we'd have two of our core because he's the he's the main guy and we connect them up

and our cores will be connected to each other and then we'll connect our routers to our core

switches this is a beautiful lovely campus network design oh so good expensive

but good okay now what's this core layer doing besides just being awesome and powerful and huge

let me show you let's go look at boson so the access layer we know he's connecting our devices are

our phones our our computers everything he's the access layer distribution we just talked about him

now the core layer what is he doing look how short his paragraph is that is truly sums it up here he's like

that massive guy at the gym just over there oh there's grunting that's all he does is grunt

and lift that's what this guy does he's just fast he and he's associated with low latency

and high reliability so the core switch is expensive reliable and

beefy because he is the network backbone and a ton of traffic goes through him he has to be able to handle a lot the

weight of the network's on his shoulders so this is our cisco three-tier network design model

core distribution access now i want to talk real quick about the the two tier the two tier had the core

layer gone but no no hold on he wasn't gone he was still there

or his role was still there that just became the job of the distribution layer let me show you real quick scroll down

through boson's amazing courseware and get to the cisco two-tier network design model

notice what they call it the collapsed core layer this model is often referred to as the

collapsed core model i don't know what happened to my id there just ignore him but the functions of the core

were collapsed into the distribution layer so the distribution switches have all the responsibilities of the

distribution switches right they have to do a bunch of the routing the inter vlan routing

access control lists and such like did they do a lot and then they have to also be the backbone of the network they

have to be powerful and crazy which in most cases is a-okay and fine i've seen more

collapse core or two-tier models than i've seen three-tier three-tier is fantastic for what i'm about to show you

right now looking back at our four buildings here here's our new design with a tier

three notice that only one of the buildings has the core layer the tier three layer and

that's the design right the core layer is the core for the entire campus so now you can imagine how

this might simplify things our distribution layers will connect back to our core layers but just to the core

layers not to each other with that full nasty mesh like we had before

this allows us to scale a lot easier if we have a massive campus so this is a bit better my drawings are horrible

let me show you a better uh view from cisco's perspective cisco has great documentation here's how buildings will

connect without a core we we just saw this just a mess it's so not scalable right it's too complex but

if you scroll down just a little bit here's our core and it solves a problem it's beautiful a lot more clean we have

our one core then we have all our tier one and tier twos and our buildings

now you want to see a core switch and how big it might be looking back at uh cisco's available distribution and

course which is what this is called find the best core and distribution switch for you um

if you are on the far right it's the smaller stuff you go to the very far left you get bigger and bigger and

bigger until you get to the big daddy the cisco catalyst 9600 series this thing's a beast they're modular so

you can just slide in extra little features and awesomeness they've got redundant everything and

look at the available backplane or bandwidth it has 25.6 terabits per second

it's pretty crazy if you want to see one of these actually david bomble and i went to cisco headquarters in in san

jose and we got to talk with the guys who designed it they walked us through it so

i got a video below if you want to check that out actually i'll play a clip right now

dude and so that's also another future proof for

delivering power they had just released it they let us take a look at it and play with it

crazy now as i mentioned before this model right here is the one i've seen the most of it's what i've worked with

the most the collapse core where you have your access layer doing its thing

on both sets of uh designs but then you have your collapse core the distribution switches also being the core switches

and then these switches will connect up to your routers when we're looking at tier three i love looking back at that

cisco example this is why you want to have a tier three when you have a bunch of buildings

in a campus that all need crazy high-speed connection to each other like they're

all in the same building so we call it a campus and really where we got the term from is like a

a college campus a school campus i went to cisco's campus and they have like a bajillion buildings i got lost

multiple times and they have stuff like this i mean they invented it right so

they invented it because they probably needed it but what i found as most companies

i've worked for we have one main corporate office and we had our core distribution switches

connecting to our access switches and that's all we needed now that's just the campus that's connecting our people and

our users in the same building we have more than that though we also have data centers and how we design our

data centers we have cloud and how we design our connections to the cloud

we have our wan we have our small office home office we have our users all kinds of different things

we're going to talk about all those here in the next few episodes now i've got some homework for you here's what i want

you to do most of you work for a company right you may be in their it department you may

not be in their it department doesn't matter what i want you to do is find out what design they have

is it two-tier is it three-tier is it some weird tier i don't know find that out and let us

know in the comments below i think they'd be really fun to see everyone's uh design

and their network and that was episode six let me know what you think comments below if you

have any questions or just suggestions let me know or if you need help let me know as well

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okay yeah that's all i got i'll catch you guys later [Music]

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