Circuit emulation maintaining transport overhead integrity

A system comprising:

• a first packet node and a second packet node communicatively coupled to form a packet connection in a packet switched network;
• a first time division multiplexed (TDM) node and a second TDM node communicatively coupled to form a first span in a TDM circuit, the first span configured to transport a TDM data transmission, the TDM data transmission comprising user data transmitted in user data paths and transport overhead data;
• and
• a third TDM node and a fourth TDM node communicatively coupled to form a second span in the TDM circuit, wherein
• the packet connection is configured to emulate a selected portion of the user data paths, the emulating comprising:
• identifying a frame in the TDM transmission, the frame comprising:
• (i) an envelope comprising the user data transmitted in user data paths and (ii) the transport overhead data;
• selecting the portion of the user data paths for emulation, comprising:
• selecting one or more user data paths, from among the user data paths in the envelope, based on determining that the selected portion of user data paths is used to carry user data;
• and
• transmitting only a portion of the data in the TDM frame using the packet connection, comprising:
• transmitting the user data included in the selected portion of the user data paths, and the transport overhead data, using the packet connection, wherein the unselected user data paths are not transmitted, and
• the second span is configured to transmit data using TDM while the packet connection is configured to transmit the selected portion of the user data paths and the transport overhead data across the first span.

A packet node in a communication network, comprising:

• a network connection that communicatively couples the packet node to a second packet node and forms a packet connection in the communication network, wherein the communication network further comprises:
• a first time division multiplexed (TDM) node and a second TDM node communicatively coupled to form a first span in a TDM circuit, the first span configured to transport a TDM data transmission, the TDM data transmission comprising user data transmitted in user data paths and transport overhead data;
• and
• a third TDM node and a fourth TDM node communicatively coupled to form a second span in the TDM circuit,
• and wherein
• the packet connection is configured to emulate a selected portion of the user data paths, the emulating comprising:
• identifying a frame in the TDM transmission, the frame comprising:
• (i) an envelope comprising the user data transmitted in user data paths and (ii) the transport overhead data;
• selecting the portion of the user data paths for emulation, comprising:
• selecting one or more user data paths, from among the user data paths in the envelope, based on determining that the selected portion of user data paths is used to carry user data;
• and
• transmitting only a portion of the data in the TDM frame using the packet connection, comprising:
• transmitting the user data included in the selected portion of the user data paths, and the transport overhead data, using the packet connection, wherein the unselected user data paths are not transmitted, and
• the second span in the TDM circuit is operable to transport data using TDM while the packet connection is configured to transmit the selected portion of the user data paths and the transport overhead data across the first span.