A method in a network device (A or F) for performing Two-Way Active Measurement Protocol, TWAMP, based path discovery, the method comprising the steps of: setting a current hopcount to an initial value of one for a TWAMP test session with a destination Internet Protocol, IP, address of another network device; transmitting, by the network device for the TWAMP test session, a TWAMP test request packet with the destination IP address and with a hopcount in the IP packet set to the current hopcount (S3, S6, 610); if, in response to the step of transmitting, an Internet Control Message Protocol, ICMP, time exceeded message is received by the network device from a transit node, then the transit node is the current hopcount away from the network device on the TWAMP end-to-end, E2E, path being discovered and the network device performs the following, adding an IP address from the ICMP message to a sequence of IP addresses recorded for the TWAMP E2E path (S5, 630), and repeating the step of transmitting with the current hopcount incremented by one as compared to the immediately preceding TWAMP test request packet for this TWAMP test session; and if, in response to the step of transmitting, a TWAMP test reply message is received, then it will have been sent from the another network device and the network device performs the following, transmitting additional TWAMP test request packets for the TWAMP test session and receiving TWAMP test reply messages responsive to respective ones of the TWAMP test request packets; and determining, responsive to the TWAMP test reply messages, a PM that is specific to the sequence of IP addresses of the forward direction TWAMP E2E path traversed by the TWAMP test session. setting a current hopcount to an initial value of one for a TWAMP test session with a destination Internet Protocol, IP, address of another network device; transmitting, by the network device for the TWAMP test session, a TWAMP test request packet with the destination IP address and with a hopcount in the IP packet set to the current hopcount (S3, S6, 610); if, in response to the step of transmitting, an Internet Control Message Protocol, ICMP, time exceeded message is received by the network device from a transit node, then the transit node is the current hopcount away from the network device on the TWAMP end-to-end, E2E, path being discovered and the network device performs the following, adding an IP address from the ICMP message to a sequence of IP addresses recorded for the TWAMP E2E path (S5, 630), and repeating the step of transmitting with the current hopcount incremented by one as compared to the immediately preceding TWAMP test request packet for this TWAMP test session; and repeating the step of transmitting with the current hopcount incremented by one as compared to the immediately preceding TWAMP test request packet for this TWAMP test session; and if, in response to the step of transmitting, a TWAMP test reply message is received, then it will have been sent from the another network device and the network device performs the following, transmitting additional TWAMP test request packets for the TWAMP test session and receiving TWAMP test reply messages responsive to respective ones of the TWAMP test request packets; and determining, responsive to the TWAMP test reply messages, a PM that is specific to the sequence of IP addresses of the forward direction TWAMP E2E path traversed by the TWAMP test session. transmitting additional TWAMP test request packets for the TWAMP test session and receiving TWAMP test reply messages responsive to respective ones of the TWAMP test request packets; and determining, responsive to the TWAMP test reply messages, a PM that is specific to the sequence of IP addresses of the forward direction TWAMP E2E path traversed by the TWAMP test session.