Method of monitoring a tandem connection in a multi-protocol label switching (MPLS) telecommunication network

A method of monitoring, in a Multi-Protocol Label Switching network, both a label-switched path and a tandem connection that is part of the label-switched path, the tandem connection comprising a sequence of successive nodes, a first of which is an input node and a last of which is an output node, the method comprising:

• receiving a first packet at the input node, the first packet having a first switching header;
• processing at the input node the first packet to generate a modified version of the first packet that includes within the first packet a recalculated first switching header and a tandem connection header;
• generating at the input node a second packet having a second switching header, wherein the second packet is a duplicate version of the first packet that includes within the second packet the recalculated first switching header;
• sending towards the output node both the first packet and the second packet;
• at the output node, identifying the second packet, and not forwarding the second packet further on the label-switched path;
• and
• at the output node, removing the tandem connection header from the first packet.