Alcatel

Alcatel Lucent

Stefan Ansorge

Martin Huck

Dieter Beller

Siegfried Beilharz

To restore a failed working path (WP) in a transport network, a restoration request is relayed between adjacent network elements (NENE) and the path set up hop by hop over spare resources by establishing local crossconnections (CCCC) conforming to the request according to routing information locally stored within the network elements. During failure free operation, a low priority path (LPP A) for extra traffic with different signal structure is allowed on the spare resources and pre-empted in the case of a failure. The restoration request is forwarded using the old signal structure of the extra traffic path. Only after reception of a confirmation sent back by the peering node (NE) using the new signal structure, the I/O port () is also reconfigured to the new signal structure.

Transport network restoration method supporting extra traffic

Transmission signals in a transport network are multiplexed from traffic streams respectively representing paths. Each path is identified with a path tag and forwarding information is provided in each network element. Failed paths in the network are restored in that the source network element crossconnects the affected traffic stream to an alternate output port and subsequent network elements receiving this unexpected traffic stream at an input port check the received path tag, determine an appropriate output port based on the tag and the forwarding information, and establish an internal cross-connection between the input port and corresponding output port.

Transport network restoration method

Failures are localized through the use of a Tandem Connection along a segment of a transmission path (P) to be monitored, non-intrusive intermediate Tandem Connection monitors (M), and temporary Tandem Connection sources created along the path segment in the case of a failure (F) in order to forward information about the fault location at least in downstream direction but preferably also in upstream direction. In particular, a failure adjacent network element (N) detects the failure and activates a temporary tandem connection source function (TS, TS). This function creates a valid tandem connection signal and insert therein a failed link identifier (TTI). The network element (N) terminating the tandem connection generates an alarm report including the failed link as indicated by the failed link identifier.

Growing community of inventors

Ohmden, Germany

Stefan Ansorge