So if we can collapse our distribution and core blocks together, when is it
required for us to have a true three-tier model?
Where we have dedicated hardware at the core and at the distribution layers, it
's separate pieces of hardware.
So let's think about a mid-size organization. Let's say that we have a
distribution block at a location.
It's connecting down into the access layer in some fashion.
And so this is one particular site. We'll call this the headquarters site. We
might have an internet block that comes into this distribution block. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
might have an internet block that comes into this distribution block.
And so so far everything is working fine except then we have a second site
added.
Site number two is much smaller but it does have dedicated distribution and
access blocks.
So this is site two. And then we're bringing the distribution block into the
other distribution block.
So where is the core in this situation? Well the core is right here in the
middle. We'll get rid of that D and we'll say hey we have collapsed. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
middle. We'll get rid of that D and we'll say hey we have collapsed.
Remember the functions of our core and the functions of our distribution block
into a single set of hardware.
So now we are switching back and forth among these different blocks here.
And that means that we're doing some amount of core functionality. So I'll get
so far and this is not a problem.
But then we add another site. So now we have site three, another distribution
block, another access block.
And at some point here we might say all right maybe it does make sense for us WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And at some point here we might say all right maybe it does make sense for us
to split off the core functions into its own dedicated hardware.
The problem is when we're talking about performing this upgrade it's a little
bit tricky to decide when exactly to perform this.
How do we identify when it's time to split off and create this three tier model
that we know we're capable of creating.
What's going to help us make this decision is when we recognize exactly what WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
What's going to help us make this decision is when we recognize exactly what
the benefits are to performing this upgrade.
Because we're going to need to justify this we're going to have to go out and
purchase additional hardware.
Justify this to our management team. And so if we understand the benefits then
we can not only properly identify when it makes sense to do so.
But we'll be able to get the money from our management in order to make that
purchase.
So what are some of the benefits to upgrading well first of all it's going to
give us dedicated resources at each layer. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Right now our switching between let's say this distribution block over here and
the internet this is going to be impacted by the relationship here between our
distribution and access model.
Meaning that if we have spanning tree protocol issues happening here then this
traffic is going to get cut off.
We might have a broadcast storm that impacts site to usability to directly
access the internet.
And so this is also going to help us create isolation of issues. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so this is also going to help us create isolation of issues.
This is something that can get overlooked a little bit because we have a layer
to domain typically down to our access block.
And so we could actually end up having broadcast storms and other spanning tree
types of issues that will impact all of the sites.
And if we have a dedicated core layer then we could have these same spanning
tree protocol issues and yet the traffic between sites two and three in the
internet would not be impacted.
It's also going to allow us to create further scaling. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
It's also going to allow us to create further scaling.
And so as we scale out to sites four and five for example I mean that is a
conversation point.
Are we planning to deploy sites four and five is that in our future.
If management says oh yeah we're going to be deploying more locations then this
isolation conversation is going to be even more impactful because we don't want
an issue at one location impacting the several locations all at once.
So from there we do need to talk about also the process of upgrading and here's WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So from there we do need to talk about also the process of upgrading and here's
the good news.
The process of upgrading is going to be fairly simple because we have
maintained our network model.
Once again the model is not locked to physical network blocks.
The model is locked to our functions.
And so as long as we have identified our functions maybe we've deployed a
routing protocol to make sure that the core side of things is working properly WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
routing protocol to make sure that the core side of things is working properly
throughout this whole process even though it's on the same hardware as the
distribution block.
If we're going to upgrade to a three tier model this isn't going to be all that
bad.
So what we would end up doing here is we would create a true core layer here.
So now we have this as a core block.
We would have to in some way make sure that we now have a distribution block
here in the middle.
We could probably repurpose our set of hardware to either go into the core or WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We could probably repurpose our set of hardware to either go into the core or
the distribution.
But the fact that we had these functions separated out in our own minds at a
minimum and potentially from a configuration perspective this is going to allow
us to very seamlessly perform this upgrade.
So what type of violation of the model would make this more difficult?
Well imagine if we had layer two extended from one site to another.
Once we had the collapsed environment that would actually have been possible WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Once we had the collapsed environment that would actually have been possible
and maybe something we did because this was collapsed core and distribution
which means that we could extend a VLAN from one location to the other.
Well now that we've split off the core and it's all layer three this would
functionally break.
So as long as again we're maintaining the model and the functions of the of
that model it's going to make it so that we have a simple process.
Otherwise if we have VLANs extended among all of these sites well that's going WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Otherwise if we have VLANs extended among all of these sites well that's going
to be a big problem.
It's going to take a while to perform that upgrade. We might even say it's just
not worth the headache unfortunately at that point.
So whether or not it's time to upgrade from a two tier model to a three tier
model is going to depend on the organization.
The focus should be on the benefits here and not only just from a network
performance perspective because yeah we get some amount of performance
improvement in all of this.
Most organizations might say okay but the collapse design is serving us well WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Most organizations might say okay but the collapse design is serving us well
enough.
Well we also need to worry about how easy it is to troubleshoot this network
and for that matter what happens when issues arise.
Because the isolation issue can make it so that once again now as we said if
there is a failure at one location like at the maybe the distribution layer of
our headquarters site.
Well now our other sites can continue to have conversations out to the internet WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Well now our other sites can continue to have conversations out to the internet
and so it does isolate and make it so that we can lock in on issues very
quickly, troubleshoot those.
And hopefully ideally maintain better uptime along with better network
performance.