Optical backplane system, switching system, and switching system upgrade method

An optical backplane system, wherein the optical backplane system comprises:

• a first upper-level optical interconnection module, a first lower-level optical interconnection module, and a second lower-level optical interconnection module, wherein
• the first upper-level optical interconnection module comprises M1 first interfaces and N1 second interfaces, and connection relationships exist between the M1 first interfaces and the N1 second interfaces;
• the first lower-level optical interconnection module comprises L1 third interfaces and K1 fourth interfaces, and connection relationships exist between the L1 third interfaces and the K1 fourth interfaces;
• the second lower-level optical interconnection module comprises L2 third interfaces and K2 fourth interfaces, and connection relationships exist between the L2 third interfaces and the K2 fourth interfaces;
• the first upper-level optical interconnection module is connected to one of the L1 third interfaces of the first lower-level optical interconnection module by using one of the N1 second interfaces;
• the first upper-level optical interconnection module is connected to one of the L2 third interfaces of the second lower-level optical interconnection module by using another one of the N1 second interfaces;
• and
• the M1 first interfaces, the K1 fourth interfaces, and the K2 fourth interfaces are configured to connect to processing modules, wherein M1, N1, K1, K2, L1, and L2 are integers greater than 1.