A method performed by a first
Provider Edge node, PE1, (121), to establish an OAM session, related to traffic service between a first
Customer Edge node, CE1, (111), and a second
Customer Edge node, CE2, (112), which traffic service relate to
data traffic via a Flex-Algo path from PE1 (121) to a second
Provider Edge node, PE2, (122), in a
transport network (100), comprising: sending a first BGP message (13) to PE2 (122), comprising a first Flex-Algo end Segment Identifier, SID, obtaining a second BGP message (14) from PE2 (122), comprising a second Flex-Algo end SID, establishing an OAM session, over the Flex-Algo path between PE1 (121) and PE2 (122), based on the first Flex-Algo END SID and the second Flex-Algo end SID, monitoring the Flex-Algo path towards PE2 (122) of the created session, and when identifying a fault in the Flex-Algo path towards PE2 (122), initiating a switch of the
data traffic to a
backup Flex-Algo path between PE1 (121) and a third
Provider Edge node, PE3, (123). Publ.