Method and apparatus for multiplex transmission

A method of multiplex transmission in a transmission network including a high- speed transmission path and low-speed transmission paths, said method comprising the steps of:

• inserting, in response to the detection of a fault on a first low-speed path, alarm information for automatic protection switching (APS) into a predetermined undefined location of the transport overhead of a multiplex signal to be sent to said high-speed path by a first multiplex transmission unit located between said first low-speed path and said high-speed path, said predetermined undefined location being distinct from APS bytes defined in the transport overhead of the multiplex signal;
• receiving the alarm information by a second multiplex transmission unit located between said high-speed path and a second low-speed path;
• and
• inserting said alarm information as APS alarm information into APS bytes of the transport overhead of a multiplex signal to be sent to said second low-speed path by said second multiplex transmission.

A multiplex transmission method in a transmission network including a high speed transmission path and low speed transmission paths, said method comprising the steps of:

• inserting, in response to the detection of a fault on a first low-speed path, alarm information for automatic protection switching (APS) into a predetermined undefined location of the transport overhead of a multiplex signal to be sent to said high-speed path by a first multiplex transmission unit located between said first low-speed path and said high-speed path, said predetermined undefined location being distinct from APS bytes defined in the transport overhead of the multiplex signal;
• receiving the alarm information by a second multiplex transmission unit located between said high-speed path and a second low-speed path;
• and
• inserting, in response to said alarm information, second alarm information into a predetermined defined location of the transport overhead of a multiplex signal to be sent to said second low-speed path by said second multiplex transmission;
• wherein said second alarm information is inserted into a framing section of the multiplex signal of said second low-speed path, and said second alarm information includes a signal which intentionally causes an out of framing failure in said framing section.

A multiplex transmission method in a transmission network including a high-speed transmission path and low speed transmission paths, said method comprising the steps of:

• inserting, in response to the detection of a fault on a first low-speed path, alarm information for automatic protection switching (APS) into a predetermined undefined location of the transport overhead of a multiplex signal to be sent to said high-speed path by a first multiplex transmission unit located between said first low-speed path and said high-speed path, said predetermined undefined location being distinct from APS bytes defined in the transport overhead of the multiplex signal;
• receiving the alarm information by a second multiplex transmission unit located between said high-speed path and a second low-speed path;
• and
• inserting, in response to said alarm information, second alarm information into a predetermined defined location of the transport overhead of a multiplex signal to be sent to said second low-speed path by said second multiplex transmission;
• wherein said second alarm information causes the halt of transmission of the multiplex signal to said second low-speed path.

A method of multiplex transmission carried out by a multiplex transmission unit located between two high-speed paths, said method comprising the steps of:

• inserting an alarm, at the occurrence of a fault on one of said high-speed paths, into a predetermined location of the transport overhead of a multiplex signal to be sent to the other of said high-speed paths, said predetermined location being capable of carrying the alarm by through-transport along said high-speed path;
• and
• sending the resulting multiplex signal to said high-speed path,
• wherein said location of insertion of the alarm is a predetermined undefined area of the transport overhead.