A network node (150, 200) for use in a packet-switched network including a Time-Division Multiplexing, TDM, pseudowire, the network node comprising: a receiver configured to receive at least one packet transmitted over the TDM pseudowire using a structure-agnostic transmission mechanism, wherein a data payload of the at least one packet comprises a framing bit and a TDM data payload; a physical interface configured to output frames to a corresponding customer edge, CE, device; a machine-readable storage medium configured to store a TDM framing type corresponding to the physical interface; a circuit emulation engine that is configured: during periods of normal operation, to transmit frames corresponding to the data payload of the at least one packet to the corresponding CE device over the physical interface, and during periods in which a network error has occurred, to transmit a plurality of frames to the corresponding CE device over the physical interface, wherein the TDM data payload of each frame includes an idle pattern, and a group of framing bits of the plurality of frames defines a framing pattern corresponding to the TDM framing type stored for the physical interface, characterised in that the framing type is predefined by a network operator to be used for the physical interface when the network error has occurred. a receiver configured to receive at least one packet transmitted over the TDM pseudowire using a structure-agnostic transmission mechanism, wherein a data payload of the at least one packet comprises a framing bit and a TDM data payload; a physical interface configured to output frames to a corresponding customer edge, CE, device; a machine-readable storage medium configured to store a TDM framing type corresponding to the physical interface; a circuit emulation engine that is configured: during periods of normal operation, to transmit frames corresponding to the data payload of the at least one packet to the corresponding CE device over the physical interface, and during periods in which a network error has occurred, to transmit a plurality of frames to the corresponding CE device over the physical interface, wherein the TDM data payload of each frame includes an idle pattern, and a group of framing bits of the plurality of frames defines a framing pattern corresponding to the TDM framing type stored for the physical interface, characterised in that the framing type is predefined by a network operator to be used for the physical interface when the network error has occurred. during periods of normal operation, to transmit frames corresponding to the data payload of the at least one packet to the corresponding CE device over the physical interface, and during periods in which a network error has occurred, to transmit a plurality of frames to the corresponding CE device over the physical interface, wherein the TDM data payload of each frame includes an idle pattern, and a group of framing bits of the plurality of frames defines a framing pattern corresponding to the TDM framing type stored for the physical interface, characterised in that the framing type is predefined by a network operator to be used for the physical interface when the network error has occurred.