The line table describes basic identification and runtime fault information on the individual subscriber line. A subscriber line consists of a port on the line card, Customer Premises Equipment (CPE) and a physical line connecting both. Fault monitoring is supported for both ends of the line. Subscriber line information consists of upstream (local port) information as well as downstream (Remote CPE) information. Downstream (ATU-C->ATU-R) information is reported by the individual port of the line card locally. Upstream (ATU-R->ATU-C) information is remote end (CPE) information which can be obtained via heartbeat messages generated by the CPE, other proprietary or standards based mechanisms. This information is proxied by the line card on the C6200 system. Entries in the table with non-assigned port have their mode disabled, so no service is available unless the port is configured and assigned to a subscriber.