Imagine you were hired to build a network for a small startup company. What
would that network look like?
Well, we're probably going to bring in the internet here
And so we're going to need some kind of edge router or firewall
And then we're probably going to connect into a handful of switches. Maybe we
've just got a
Primary switch here in one of the access closets for our users to connect to
and then we've got another switch over here
Maybe in another part of whatever space we're leasing and that will connect to
the rest of the network
And from there we might even want to connect a few access points for wireless WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And from there we might even want to connect a few access points for wireless
connectivity
So this would be the extent of the network, but guess what this particular
startup company is going to expand and grow very quickly
And so they're coming to you now and saying hey that network you designed it
needs to be bigger. We need more
wired connections
So I'm gonna scale out here my
My switches we're going to take over another part of the least building. We're
going to need another switch out there
We're going to need more access points and eventually we start to create a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We're going to need more access points and eventually we start to create a
network that looks like it's kind of a mess
This is the concept of organically growing out our network and it starts to hit
some big concerns
For example, what about the redundancy in this network design?
What happens if the internet goes down? What happens if this one switch right
here?
Where to fail the entire network would lose access to first of all the internet
and
Second of all this section of the network wouldn't be able to talk to this WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Second of all this section of the network wouldn't be able to talk to this
section of the network if that's even
valuable with the internet being down in many cases. It's not we might need
some my some number of servers to run our
applications
So we might have some kind of sales or
Sales type of application that we want our sales folks to have we might have
engineering applications
Whatever that looks like we're going to need to put some servers and
Some maybe storage arrays out on the network WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Some maybe storage arrays out on the network
But where exactly does that go?
We've pegged this switch for that
But does that really make the most sense for it to be there?
Especially if we also have laptops and other PCs hanging off that same switch
What happens when we introduce a whole other site?
All together so now we have site two and we're going to have some kind of
router there and a switch for the local users
How do I connect this network into the rest of the network that I'm building WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
How do I connect this network into the rest of the network that I'm building
out?
So this is a concern and again organically growing out a network can be painful
It would be a whole lot better if we had an architectural model
Well, fortunately we do have an architectural model. We're all here to talk
about the hierarchical network model and
The hierarchical network model is intended to give us a set of guidelines
That's going to help us to build a network out to achieve some of these WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
That's going to help us to build a network out to achieve some of these
concerns
For example, we do want to focus on redundancy giving us a redundant design
But importantly and something that we didn't add to the list down here. We
probably could and
Should is
Scaling we want to be able to address the need to grow it worked out fine when
our network was this big
The original network that we deployed for a very small set of users
But as we grew we started to see that just throwing a couple of switches out WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But as we grew we started to see that just throwing a couple of switches out
there with a router was
Not something that was intended to grow beyond its original scope
So we need something that allows us to grow and add and expand and we're not
just talking about
local users
But we're also talking about
Different sites. We're talking about maybe even bringing in more redundant
internet circuits
So we need to consider the internet in this
We need to consider the wide area network this connection right here that's WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We need to consider the wide area network this connection right here that's
going to connect my site to
Into site one and for that matter where are we going to put those servers?
That are running the applications and storing the data for our users so that
they can do their jobs
The goal of the hierarchical network model is to show us how to get all of this
Using a blueprint that is going to be a starting point the idea here
Is that we don't want to get stuck we want to have a starting point and be able WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Is that we don't want to get stuck we want to have a starting point and be able
to grow as much as possible or as much as needed over the course of time
And what we're going to find is this model ends up giving us a building block
type of architecture
We think back to kindergarten and having different building blocks being able
to just put a block down and put another block here
And maybe I put another block next to it and I stack it up and make a tower the
idea of this building block type of architecture is to say that each one of WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
idea of this building block type of architecture is to say that each one of
these
Could be a different part of the network and I just need them to be able to be
inserted or removed
Depending on the current network needs here's what this looks like from a
network perspective
We want some kind of network core that sits in the middle of our network a lot
of us have studied
The core distribution access layer types of models. Those are part of CCNA
studies and now it's time to get a little more detailed WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
studies and now it's time to get a little more detailed
Because the core of the network isn't just a layer. It is a block
Again, this is part of the building block architecture which is intended to
allow us to scale out
So what if I do want to have a core distribution and access layer type of model
?
Well, no problem. I'm going to build a distribution block
And I'm going to connect the distribution block into the core block
And then I know that my access block is going to hang off of that distribution WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And then I know that my access block is going to hang off of that distribution
block and
So far this doesn't look a whole lot different than anything else that maybe we
've studied in the past
However, now let's start to scale this up
Beyond what a single site would look like because I might have another site
that is a second distribution block
That also has an access layer
I'm going to want to connect up into an internet block up here as well as a
wide area network block
And for that matter, I probably would want to start thinking about these WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And for that matter, I probably would want to start thinking about these
servers and connecting to some kind of primary data center block as well
And for that matter, maybe we want a backup data center
And so as we zoom out and we look at this network design, this is going to look
a little bit like a hub and spoke
I guess I so wrote spoke first
Hub and spoke or spoke in hub type of topology
I'm going to put this in air quotes because when we talk about a hub and spoke WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I'm going to put this in air quotes because when we talk about a hub and spoke
from the perspective of network
Architecture usually what we're talking about is a switch that connects to
another switch up here and another switch down here
But we're not talking about switches here
We're talking about blocks
Our different
Building block architecture here is going to allow us a number of things first
of all anytime
I want to add another block
I simply have to deploy the block and connect it into the network core WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I simply have to deploy the block and connect it into the network core
Yeah, my drawing is really pretty with exactly nine blocks here
But I just added a tenth block and from an architecture perspective
I just did with this block what I did with all the other blocks
This might be as a completely new site site number three
And it's another distribution block that's going to plug into the core
I can do this as many times as needed because the purpose of the core is to
serve as that hub
Which is going to connect all of the different network components together WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Which is going to connect all of the different network components together
Or all of the different places in my network should be able to reach one
another through the network core
So this is an expansion of what we might refer to as the enterprise campus
model
Which is something that we study a little bit more off and that involves once
again the core
distribution and access layers
And we're going to be drilling into the details of what this looks like as well
But it is important for us to recognize that there's a lot more places in the
network than just the core distribution and access WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
network than just the core distribution and access
We have needs for other network locations
And if we try to build out a network organically like this and just keep
feeding one switch off of another
And deploying things on an as needed basis
Then this is going to fail from a scaling perspective
And we compare that to this modular architecture
Which allows us to both add blocks and remove blocks on an as needed basis
Well now we can truly scale up our network WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Well now we can truly scale up our network
Starting with something very small with the current needs
And being able to grow our network to enterprise level and even global
Corporation type of level using this model