SDN Controller Cross-Subnet Wi-Fi Service Discovery

The patent introduces a border router as an intermediary device between subnets. The border router captures multicast service discovery packets, converts them to unicast packets, and forwards them to other subnets. This intermediary mechanism enables service discovery across subnets while maintaining the original multicast-based service availability within each subnet, thus resolving the contradiction between service reliability and extendability.

The patent inverts the traditional multicast flooding approach by converting multicast packets to unicast packets at the border router. Instead of flooding multicast packets across all subnets (which causes excessive traffic overhead), the border router sends targeted unicast packets only to the specific subnets where service discovery is needed. This inversion of the packet transmission method achieves service extendability while minimizing network traffic overhead.

The border router acts as a mediator that controls and regulates service discovery traffic between subnets. By capturing multicast packets and converting them to unicast, the border router prevents uncontrolled multicast flooding that would destabilize the network. The intermediary mechanism ensures that service extendability is achieved through controlled, targeted packet transmission rather than uncontrolled flooding, thus maintaining network stability.

The patent implements self-service by enabling devices to automatically perform service discovery without manual configuration. Devices send multicast service discovery packets, and the border router automatically captures, converts, and forwards these packets across subnets. This self-service mechanism maintains ease of operation for end devices while the border router handles the complexity of cross-subnet communication automatically, thus resolving the contradiction between ease of operation and network complexity.