A method of operating a communication network, wherein the communication network comprises a plurality of electronic devices (100,..., 112) coupled via a plurality of communication links, said plurality of communication links comprising at least one first communication link over a first physical medium and at least one second communication link over a second physical medium, the method comprising: - issuing, at an originator device in the plurality of electronic devices (100,..., 112), a path request message encoded according to ITU-T G.9903 standard directed towards a destination device in the plurality of electronic devices (100,..., 112), - transmitting said path request message from the originator device to the destination device through a first set of intermediate devices via a forward sequence of communication links in said plurality of communication links, - issuing, at the destination device, a path reply message encoded according to ITU-T G.9903 standard directed towards the originator device, and - transmitting said path reply message from the destination device to the originator device through a second set of intermediate devices via a reverse sequence of communication links in said plurality of communication links, wherein transmitting said path request message via a communication link in the forward sequence of communication links comprises setting a respective channel type field (C1-F,..., Cn-F) of the path request message to a value indicative of the physical medium used in said communication link in the forward sequence of communication links, said respective channel type field (C1-F,..., Cn-F) of the path request message being located between a respective metric not supported field (M1-F,..., Mn-F) and a respective link cost field (HOP1-FPLC,..., HOPn-FPLC), and wherein transmitting said path reply message via a communication link in the reverse sequence of communication links comprises setting a respective channel type field (C1-R,..., Cm-R) of the path reply message to a value indicative of the physical medium used in said communication link in the reverse sequence of communication links, said respective channel type field (C1-R,..., Cm-R) of the path reply message being located between a respective metric not supported field (M1-R,..., Mm-R) and a respective link cost field (HOP1-RPLC,..., HOPm-RPLC). - issuing, at an originator device in the plurality of electronic devices (100,..., 112), a path request message encoded according to ITU-T G.9903 standard directed towards a destination device in the plurality of electronic devices (100,..., 112), - transmitting said path request message from the originator device to the destination device through a first set of intermediate devices via a forward sequence of communication links in said plurality of communication links, - issuing, at the destination device, a path reply message encoded according to ITU-T G.9903 standard directed towards the originator device, and - transmitting said path reply message from the destination device to the originator device through a second set of intermediate devices via a reverse sequence of communication links in said plurality of communication links, wherein transmitting said path request message via a communication link in the forward sequence of communication links comprises setting a respective channel type field (C1-F,..., Cn-F) of the path request message to a value indicative of the physical medium used in said communication link in the forward sequence of communication links, said respective channel type field (C1-F,..., Cn-F) of the path request message being located between a respective metric not supported field (M1-F,..., Mn-F) and a respective link cost field (HOP1-FPLC,..., HOPn-FPLC), and wherein transmitting said path reply message via a communication link in the reverse sequence of communication links comprises setting a respective channel type field (C1-R,..., Cm-R) of the path reply message to a value indicative of the physical medium used in said communication link in the reverse sequence of communication links, said respective channel type field (C1-R,..., Cm-R) of the path reply message being located between a respective metric not supported field (M1-R,..., Mm-R) and a respective link cost field (HOP1-RPLC,..., HOPm-RPLC).