Generally speaking, network topology design is divided into two types: single core and dual core.
1. Single-core network topology design
(The picture above shows the router connecting to the external network, but it can also connect to other branches of the company, the same below)
A single-core network means that there is only one core switch in the entire network environment. This topology is suitable for enterprises whose network is not too large and does not rely heavily on the network. Since core equipment, such as CISCO equipment, is relatively expensive, most companies use a single-core network topology design.
However, this design has a fatal flaw and can easily cause a single point of failure. When engineers realized this problem, a second topology was created.
2. Dual-core topology