In Figure 1, a campus network consists of a student area and a teacher area.
As the students are more in number, their packets are transmitted through the education network. If access to the education network fails, students packets are transmitted through the backup telecom network. The number of teachers is less than the number of students and has higher network service requirements. When any user, including both teachers and students, attempts to access resources on a specific network, user traffic will be preferentially transmitted through the requested network, which can be education or telecom network. Therefore, the teacher packets are transmitted through the telecom network. If access to the telecom network fails, teacher packets are transmitted through the education network. Teacher and student packets are transmitted through different outbound interfaces, and these outbound interfaces back up each other. Such a network may also be used by a large enterprise.