Neighbor Discovery for Ethernet Private Line on User Network Interfaces

A transport network device in an optical network, connected over an Ethernet connection to a client layer device, the transport network device transparently mapping Ethernet packets to multiplex units and vice versa, the transport network device comprising:

• a first multitude of ports, where a port of the first multitude of ports is connected by the Ethernet connection to the client layer device;
• a second multitude of ports provided for establishing at least one optical link to at least one other transport network device;
• and
• a link configuration pattern generator coupled to the first and second multitude of ports, said link configuration pattern generator being configured to determine whether a signal is received at the port of the first multitude of ports, and configured to control the port of the first multitude of ports to send a link configuration pattern, the link configuration pattern being one of:
• a predetermined bit sequence, an invalid Ethernet packet and a valid Ethernet packet, wherein an invalid Ethernet packet is a packet that would normally be discarded according to the Ethernet protocol, the link configuration pattern containing a device identifier identifying the transport network device and a port identifier identifying the port of the transport network device.

A client layer device that is coupled over an Ethernet connection to a transport network device, the client layer device comprising:

• a port connected via the Ethernet connection to a port of the transport network device;
• and
• a link configuration pattern generator configured to control the port of the client layer device to send a link configuration pattern, the link configuration pattern being one of:
• a bit sequence, an invalid Ethernet packet and a valid Ethernet packet, the link configuration pattern containing a device identifier identifying the client layer device and a port identifier identifying the port of the client layer device.