Synchronous/asynchronous system having function of switching path upon fault

A composite asynchronous/synchronous system having the function of switching signal paths at the time of a fault, comprising:

• a synchronous communication system (10) having a path termination office (13B) inserted in a pair of ring-like transmission lines (11 and 12) through cross-connect equipment (61) and including a path switch (17) for switching from a synchronous mode path signal input from one of the ring-like transmission lines to a synchronous mode path signal input from the other line when the path termination office detects that there is a fault included in the synchronous mode path signal in said one transmission line;
• an asynchronous communication system (19), which transmits an asynchronous mode signal and is combined with the synchronous communication system,
• said composite asynchronous/synchronous system being provided with overhead data creation units (41) which are provided in the two connection offices (13A, 13A') connecting said synchronous communication system and said asynchronous communication system by two routes and which create a fault detection signal as path overhead data when a fault detection signal is issued from a fault detection unit (36) of said asynchronous system showing one of suspension of said asynchronous mode signal and a fault in the asynchronous signal, and being provided with
• a path overhead monitor (42) in said path termination office for detecting the fault detection signal in said path overhead sent in the said path signal, and cross-connect control means (64) in the path termination office for changing the cross-connect settings at the cross-connect equipment by the output of the path overhead monitor (42).

A composite asynchronous/synchronous system having the function of switching signal paths at the time of a fault, comprised of

• a synchronous communication system (10) having a path termination office (13B) inserted in a pair of ring-like transmission lines (11 and 12) through cross-connect equipment (61) and including a path switch (17) for switching from a synchronous mode path signal input from one of the ring-like transmission lines to a synchronous mode path signal input from the other transmission line when the path termination office detects a path alarm indication signal AIS showing one of (a) a suspension of the synchronous mode path signal on said one transmission line and (b) a fault in the synchronous path signal on said one transmission line;
• an asynchronous communication system (19) which transmits an asynchronous mode signal and is combined with the synchronous communication system,
• said composite asynchronous/synchronous system including asynchronous system fault notifying means (31) which are provided in each of two connection offices (13A, 13A') connecting said synchronous communication system and said asynchronous communication system by two routes, said asynchronous system fault notifying means sending to said path termination office a fault detection signal when detecting an AIS from said asynchronous communication system showing one of (a) suspension of said asynchronous mode signal and (b) a fault in that asynchronous signal, each of said asynchronous system fault notifying means including an alarm reporting unit (46) which sends said fault detection signal to an existing maintenance center (45) which centrally monitors and controls the overall composite asynchronous/synchronous system, and
• cross-connect means (64) which is provided in said path termination office and which changes the cross-connect settings at the cross-connect equipment (61) in response to a cross-connect setting change command transferred from the maintenance center.