Patent ID: 8391163

Claim:
A method, comprising: transmitting, from an initiating maintenance end point (MEP), a lock message to lock a circuit, traversing one or more maintenance intermediate points (MIPs) between the initiating MEP and an end MEP, to data plane traffic; transmitting, from the initiating MEP, an in-band packet containing a loopback request to a particular MIP along the circuit using a particular time-to-live (TTL) value in the in-band packet to reach the particular MIP; receiving the in-band packet at the particular MIP; in response to determining that the particular TTL value has expired at the particular MIP, inspecting the in-band packet to discover the loopback request; operating the circuit in loopback mode at the particular MIP in response to the loopback request; transmitting a cease loopback request packet to the particular MIP using the particular TTL value in the cease loopback request packet; receiving the cease loopback request packet at the particular MIP; in response to determining that the particular TTL value has expired for the cease loopback request packet at the particular MIP, inspecting the cease loopback request packet to discover a cease loopback request; and exiting loopback mode at the particular MIP in response to the cease loopback request.