Bridging Devices for Cross-Network SSDP Discovery
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Solution Overview
Problem
Devices within separate local area networks using the Simple Service Discovery Protocol (SSDP) cannot communicate with each other due to the protocol's limitations in transmitting traffic between networks, as it is designed for closed networks and internet routers do not route multicast packets effectively.
Innovation Solution
A system comprising bridging devices and a management server that encapsulates SSDP messages into internet protocol packets for transmission between networks, allowing authorized devices to share content across different local area networks by inferring network structures and using filtering rules to manage data exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SSDP messages are transmitted using multicast protocol within a closed local network, then device discovery and communication work effectively, but the messages cannot be routed between separate local area networks
Solution Approach 1:
A gateway device is introduced as an intermediary between separate local area networks. The gateway receives SSDP multicast messages from one network, encapsulates them in unicast IP packets, and forwards them to the target network. This mediator enables cross-network communication while preserving the original SSDP protocol functionality within each network boundary.
Solution Approach 2:
The system segments the communication process into distinct stages: (1) SSDP multicast transmission within the source network, (2) message capture and encapsulation by the gateway, (3) unicast IP packet transmission across networks, and (4) decapsulation and local multicast transmission at the destination network. This segmentation allows each stage to operate with the appropriate protocol for its context.
2Adaptability or versatility
If SSDP messages are encapsulated and forwarded between networks using a gateway, then cross-network communication is enabled, but the system complexity increases with additional devices and protocols
Solution Approach 1:
The gateway device is designed with multi-functionality to reduce overall system complexity. It simultaneously performs SSDP message capture, IP packet encapsulation, routing decisions, and local network transmission. By consolidating these functions in a single device rather than requiring separate specialized components, the system achieves cross-network interoperability without proportionally increasing complexity.
3Loss of information
If all SSDP messages are forwarded between networks, then complete device visibility is achieved, but network traffic congestion and security risks increase
Solution Approach 1:
The gateway implements selective message forwarding based on local quality assessment. It examines each SSDP message's destination address and forwarding rules to determine whether to forward, filter, or block the message. This selective approach ensures that only relevant device discovery messages are transmitted across networks, maintaining device information completeness while preventing traffic congestion and reducing security risks.
Data Source
AI summary
A system is provided comprising a first bridging device associated with a first internet protocol (IP) address having a radio transceiver receiving simple service discovery protocol (SSDP) messages from devices on a first media local area network (LAN), encapsulates and transmits the messages to a second address. The system also comprises a server associated with the second address receiving the messages from the first bridging device. Based on the messages, the server constructs a list of the devices on the first network. Based on a rule, the server forwards at least some of the messages received from the first bridging device to a third address. The system also comprises a second bridging device associated with the third address with a transceiver that receives the messages forwarded to the third address, decapsulates the simple service discovery messages, and wirelessly broadcasts the messages to devices on a second media local area network.