Airport Communication Navigation Dual-Network Mutual Backup System Switching Equipment

Keywords: Communication Equipment Mutual Backup, Dual-Interface Mutual Backup, Dual-Board Mutual Backup, Dual-Machine Mutual Backup, Dual-Network Mutual Backup

In some important remote dispatch and control sites (such as subways, airports, and military facilities), high system reliability is often required. It is common for services to be transmitted over two or more networks, with user terminals automatically selecting the normal transmission network and channel. This necessitates the provision of an automatic service switching system that features high reliability, strong maintainability, and the ability to accept independent control from network management systems of multiple networks, as well as automatic switching based on service interface status. Therefore, the switching equipment is required to use as few active components as possible to reduce the failure rate of the switching equipment itself, and to have multi-network switching interlock functionality!

Common methods for enhancing system reliability include dual-interface (such as dual optical ports, or optical-electrical mutual backup) mutual backup, dual-board mutual backup, dual-machine mutual backup, and dual-network mutual backup. Dual-board mutual backup is mostly used within equipment, such as dual power supply boards, dual main control boards, etc.; dual-machine mutual backup includes cold standby and hot standby; dual-network backup means that each service is transmitted through two networks, and the receiving end selects the better reception, which typically requires user interfaces to be completed through selection and switching equipment.

Common user service interfaces include Ethernet interfaces, narrowband data ports such as V.24/V.35/RS422/RS485, audio interfaces, telephone interfaces, etc. To achieve optimal selection switching and manual forced switching of user ports, different types of interfaces require different handling methods.

For Ethernet interfaces, the method of simultaneous transmission and reception over dual networks is typically adopted. When one network fails, the bandwidth is automatically reduced by half. The switching of narrowband data usually involves sending the same content simultaneously over both networks, with the receiving end automatically receiving data from the first network that has data. For these data channels, line bit errors are not considered; when bit errors occur on the line, a switching command is issued through the network management system. For voice channels, the signaling status is prioritized for judgment; when signaling statuses are the same, it is determined whether voice data is present. If both signaling and data are identical, the default network is preferred. These judgments are typically implemented on digital lines.