So far, we have worked with single containers. But in reality, a containerized business application consists of several containers that need to collaborate to achieve a goal. Therefore, we need a way for individual containers to communicate with each other. This is achieved by establishing pathways that we can use to send data packets back and forth between containers. These pathways are called networks. Docker has defined a very simple networking model, the so-called container network model (CNM), to specify the requirements that any software that implements a container network has to fulfill. The following is a graphical representation of the CNM:
The Docker container network model
The CNM has three elements—sandbox, endpoint, and network: