The Cisco three-layer model was developed to curb the complexities that exist in the various models available for designing a network. The Cisco three-layer model is a hierarchical model that aids the design and implementation of a reliable network with great scalability and is still considered cost-effective. One great advantage of the Cisco three-layer model is the ability to create a high-performance network. This shot will cover the three layers, which include the core layer, distribution layer, and access layer.
The core layer is able to transport a large amount of traffic through a network in less time. The core layer is also able to grant the devices in the next layer of the network model, which is the distribution layer inter-connectivity. The devices transport data at a very high speed. Some of the devices on the core layer are expensive routers, which help in the interconnection of networks that are geographically separated.
The core layer is considered the backbone of the network in the Cisco network model. Any fault in the core layer of the network affects the rest layers of the network, which is why speed and latency are a big concern in the core layer of the network in this model. In summary, the core layer of the Cisco three-layer model consists of expensive devices with a high volume of traffic in data transfer and helps to interconnect with the distribution layer.
The distribution layer is like a middle-man in the layers of the Cisco model, meaning that it provides an interconnection between the top layer, which is the core layer, and the lower layer, which is the access layer. The distribution layer carries out the routing protocol function for the network model and performs filtering and wide area network access. The distribution layer decides how data/packets can be transported to the core layer.
The devices at the distribution layer are more of multi-layer switches and some routers, which help in the provision of access lists and filters used in the connection of the core and access layer. So, we can say the policy of a network is defined by the distribution layer.
The distribution layer ensures that packets have a known source and destination address by making the necessary protocols available in the network. The distribution layer is also concerned with the security of the network and firewalls.
The access layer is where the network users can interact with the network with user-end devices. The access layer consists of access switches that are connected to user-end devices. Simply put, the access layer controls the user’s access to the network.
The access layer can implement some access control policies and helps in network segmentation. The access layer can possibly aid workgroups to connect to the distribution layer of the network.
The Cisco three-layer network model is of great advantage over some models that have complexities, as it helps in creating a high-speed performance network with security.