o enable mac address failed The attempt to enable the MAC address failed on a broadcast circuit with a nonzero Phase IV address. o no such data link Data link specified for this circuit does not exist. o open port failed A port cannot be opened on the specified data link. o open rip port failed The UDP port for RIP (port 520) could not be created. o routing not enabled The Routing module is not in the on state. o subnet address not unique One of the subnet addresses for this circuit is the same as the subnet address for another circuit.