With the rapid development of rail transit, the subway has become an indispensable important means of transport. With years of experience in the design and maintenance of rail transit information and communication, the company has a number of subways such as Beijing Metro Daxing Line, Line 4, Nanjing Metro Line 1, Line 2, Line 3, Line 10 and Airport Line line. It has deployed a large number of large-scale IP bearer networks for rail transit, aggregated data and video transmission services.