CISCO 3 TIER ARCHITECTURE

When we have a big Campus Network then the Campus Network Architecture should be
" 3- Tier Architecture "

These Architecture will be having 3 layers -

1) Access Layer

2) Distribution  / Aggregation Layer

3) Core Layer

Each Building in the Campus will be having Access & Distribution layer components which will be connected to the Core Layer.

CISCO 3 TIER ARCHITECTURE

1) Access Layer :-

Provides Access to the Network.

This layer will have Components / Equipment through which a user can access the network .

If the Campus have 50,000 employee then these 50,000 employees will be connected to the access -layer devices .

L2 Switches are required in this layer

VLAN are created on the switches - Some ports of the access switch may be in vlan 100 , some ports may be in vlan 200 etc. depending upon the services required by the users.

These Access layer switches should have Trunk Capabilities - Multiple vlans are created on access switches hence there up-links connecting to the Distribution switch must be capable of  carrying multiple vlan traffic hence they should have trunking capabilities .

The uplink should be according to the port capacity of the downlinks where the users will be connected .

The access layer switches ports should have properly configured port level security so exclude any chance of the misuse of the network.

Access Layer Device -

L2 Devices

Cisco Switches - 2960 , 3560 , 3750 , Modular switches like 4500 Series etc.

Cisco Nexus Switches - N9K Switches , N5K Switches .

2) Distribution Layer :-

In Distribution Layer L3 /Multilayer Switches (MLS ) are used .

They should be capable of handling Intra building communication .

Vlan Aggregation - All the vlans are terminated on  Distribution Layer

Intervlan Routing is preformed on this layer devices.

This Layer devices breaks the broadcast domain.

QoS is provided in this  layer.

L2 / L3 Security is provided on this layer

Maximum Traffic Manipulation.

Devices used :-

4500 / 6500 series Switches

Cisco Nexus 7K Series Switches .

3) Core Layer :-

Simple L2 function only .

Just Forwards the traffic which comes from one building to the desired destination Building.

These switches should have very high port density.

No Traffic Manipulation - There should be no delay in the communication .

Devices Used:-

Cisco 4500 . 6500 (Layer 2 function only)

Cisco Nexus 9k switches .

Thanks for Reading !!!!!