A method and apparatus are disclosed for monitoring and signaling a path
restoration using pre-computed restoration paths following a detected
fault on a primary service path in a communications network. A fault
occurring inside the restorable portion of a network in heterogeneous or
multiple network environments can be distinguished from faults occurring
outside the restorable network in accordance with the ANSI Tandem
Connection Maintenance standard, T1.105.05-1994. Path restoration is
activated only when a fault causing path failure occurs inside the
restorable portion of the network. Each conforming node in the restorable
portion of the network has the necessary monitoring, signaling and
cross-connect functionality and databases to participate actively in real
time restoration. Additional non-conforming network elements can be
positioned between the restoration nodes without preventing path
restoration. With the signaling architecture of the present invention,
when an end-node detects a path failure caused by an in-network fault, it
formulates a signaling message for restoring the failed path. The
restoration signaling message is thereafter relayed from one node to
another in the overhead or payload of signaling paths that occupy the
same bandwidth that is subsequently used by the restoration path. Once a
signaling message is transmitted to an adjacent node in the overhead or
payload of a particular signaling path, the node that transmitted the
message makes a cross-connect that replaces the signaling path with a
segment of the restoration path whose set-up was requested in the
transmitted signaling message.