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In our next section we will talk about some network topology architectures the three to architecture

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guys consists of three different layers and they are access layer distribution layer and the core layer

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the core layer is in charge of first routing simply and it is the layer which is a gateway to Internet

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or other sites.

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And the core layer also provides scalability and the first three coverage and skies when it comes to

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distribution layer in this layer we have multiple multilayer switches capable doing routing also and

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they have a high capacity and high port speed and density and this layer aggregates the server access

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layer using switches to segment work groups and isolate network problems in a datacenter environment

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and the last layer we will talk about is the access layer we can use the layer two switches in this

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layer because we are not based on routing but in some mac address forwarding just the access layer is

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a layer that is used to guarantee user access to the network to ISIS and mostly on access layers which

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we have some end user pieces some printers some IP cameras and et cetera.

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All right.

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P. cam and that cetera.

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OK so let's go ahead with the truth here now the three tier a high risk hierarchical design maximizes

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performance network availability and the ability to scale the network design.

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Yeah three tier is really great but many small enterprise networks do not grow significantly larger

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over time.

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Therefore a two tier hierarchical design where the core and the distribution layers are collapsed into

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one layer is often more pretty practical a collapsed core is when the distribution layer and the core

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layer functions are implemented by a single device.

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The primary motivation for the collapse core design is reducing the network cost while maintaining most

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of the benefits of the three tier hierarchical model.

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Now let's finish this session with the spine Leif for a long long time we have talked about Cisco's

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two tier and three tier network design where we just talked about and we had the following players access

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this probation and car the access layer connected to our end devices such as clients and servers.

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However within two days data centers and new topological design has taken over and it is called spine

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and live.

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So imagine a cabinet in a data center filled with servers guys for acutely.

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There will be a couple of switches at the top of each rack and for redundancy.

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Each server in the rack has a connection to both of these devices.

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You might have heard the term top of rack used to refer to these kinds of switches because they physically

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do side in the top of a rock already.

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These tea or are switches acts as as the loose in a leaf and spine topology ports in a live switch.

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Have one of responsibilities and one connecting to you.

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Note You can see in here.

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And second connecting to air space which you will notice in the topology on the screen that each leaf

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switch connects to a wrist band switch.

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You can see the lift switches in here and here we are connected to this switch here connected to this

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storage.

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And here we are connected to this spine switch.

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So as a result there is no need for interconnections between the spine suites.

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Okay you can see there is no interconnection between the spine switch also the lift switch as well it

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is also interesting to note that the uplink connections from the left switches to the spine switches

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could be either layer two connections or layer three router connections by interconnecting your T or

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our data center switches in a leaf and spine topology all of your switches are the same distance away

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from one another.