In an enterprise network, we have 3 layered hierarchical models for designing a reliable network infrastructure. This three-layer model helps you design, implement, and maintain a scalable, reliable, and cost-effective network. Each layer has its own features and functionality, which reduces network complexity.
We will discuss these layers from the bottom to the top.
Cisco has a three-layer hierarchy when we talk about the network design, In the access layer, we have lots of devices like our access switches, and Access point from where our end hosts are connected, this is just an entry for all of our network hosts. Normally the switches we use are 3550,2960, and switches etc.
From the configuration point of view we may have VLAN access, Layer-2 QoS marking or maybe some layer 2 security features like Dhcp Snooping, Storm control etc etc .
In Distribution Layer, we use normally routers or layer 3 switch for QOS implementation, Layer 3 routing, VLAN gateway,etc etc. The distribution layer serves as the communication point between the access layer and the core. Its primary functions are to provide routing, filtering, and WAN access and to determine how packets can access the core.
In the core Layer, We use devices called high-end routers or firewalls. Those are going to be the gateway to the internet or outside our network. Basically, in an enterprise, we use the redundancy internet connection where we do the path manipulation, Layer-3 security.
Note:- we must have redundancy in the core for routing in the failure.
Collapsed Layer Design
It is not necessary to follow these hierarchies always in the case of a small size network. This 3-layer hierarchy is just a standard but you can skip one of these layers if you cant afford it in terms of finances and if you don’t have huge network utilization.