Apparatus and method to monitor communication system status

A method for monitoring a communication system, comprising:

• receiving at a central office a first upstream optical signal at a first frequency;
• said first upstream optical signal formed remotely from the central office by converting an upstream electrical signal;
• transmitting from the central office a downstream optical signal;
• receiving at the central office at least part of a second upstream optical signal, the second upstream optical signal comprising a result of mixing at least part of a downstream electrical signal formed from converting the downstream optical signal;
• and
• monitoring both the first and the second upstream optical signals at the central office to determine a state of the remote node.

A method for monitoring a communication system, comprising:

• receiving at a central office at least part of a first upstream optical signal, the first upstream optical signal comprising a result of converting a first upstream electrical signal;
• transmitting from the central office a downstream optical pilot signal;
• receiving at the central office at least part of a second up stream optical signal, the second upstream optical signal comprising a result of mixing at a remote node:
• at least part of a downstream electrical signal formed from converting the downstream optical pilot signal, and
• at least part of the first upstream electrical signal;
• and
• monitoring both the first and the second upstream optical signals at the central office to determine a state of the remote node, wherein if the first and second upstream signals comprise only the pilot signal, then it is determined that a distribution path downstream of the remote node is inoperable.