Patent ID: 7394980

Claim:
A communication network for testing a circuit having a production channel and a spare channel, the communication network comprising: a production channel transponder comprising: production short reach receiver circuitry configured to receive a first short reach signal on the production channel; production long reach transmitter circuitry configured to transmit on the production channel a first long reach signal based on the first short reach signal; production long reach receiver circuitry configured to receive on the production channel a second long reach signal; production short reach transmitter circuitry configured to transmit on the production channel a second short reach signal based on the second long reach signal; the communication network characterized by: a spare channel transponder comprising: generator circuitry configured to generate a test signal; a connector configured to connect the generator circuitry to spare short reach transmitter circuitry; and the spare short reach transmitter circuitry being further configured to transmit on the spare channel the first short reach signal based on the test signal from the generator circuitry over a first patch link to the production short reach receiver circuitry.