An initial proposal calling for point-to-point 以太网 开关 and 串口服务器s was soon discarded because of several important limitations including: 1) it didn't support handshaking signals; 2) it didn't offer redundancy; and, 3) it offered minimal flexibility for long term growth.

To preserve overall network interoperability and upgrade to a packet-based communications system, the Metro opted to go with TC Communication’s JumboSwitch® Multi-Service 以太网 Platform.

据一位网络经理说, the JumboSwitch was a proven commodity because it had been successfully deployed in similar applications (e.g. 洛杉矶Metrolink, Melbourne Metro Australia and Canadian National Railway) and it provided a unique RS485 interface with handshaking that was required by the upgraded vital controllers. 除了, it supported all of Metro’s additional legacy serial connections to vital controllers as well as 以太网/IP connections to new controllers in the future.

The JumboSwitch’s multi-service TDM / IP /以太网 capability preserved the Metro’s existing legacy network and will enable it to expand or build out the network (and add 以太网 devices such as cameras, IP电话, 等.)在未来几年以自己的速度发展. The JumboSwitch also enabled the Metro to condense three of its existing fiber rings into one fully redundant fiber ring network.

安装完成后, a total of 20 nodes with JumboSwitch 4U chassis units, each populated with two RS232 [4 ports each] and two RS485 [2 ports each to accommodate DB9 connectors] serial interface cards (see Fig 1. 网络框图), will be deployed to link vital controllers and computers at multiple signal houses and stations.

For redundancy, each JumboSwitch unit will have two duplicate Master/Slave cards. 配置, 政府, 监控, and troubleshooting of the JumboSwitch network will be handled by the JumboSwitch’s IP-based network management management system, TCV背影®.