Importance

Loading Importance Indicators...

Abstract

During ISDN signal transmission from a network trunk line (21) to an access line (18), a word (202) provided from the network trunk line is broken into two bytes including a data byte (205) and a performance monitoring byte (206). After signal transmission through common equipment (14) and an access line shelf (10), a line card (12) verifies the composite parity of the data byte and the performance monitoring byte to determine if an ISDN signal transmission error has occurred. During ISDN signal transmission from an access line (18) to a network trunk line (21), the line card (12) forms a data byte (305) by combining pairs of data bits from the access line, and simultaneously forms a performance monitoring byte (306) by combining pairs of performance monitoring bits corresponding to the pairs of data bits. After signal transmission of the data byte and performance monitoring byte through the access line shelf and common equipment, logic (65) is provided to determine if an ISDN signal transmission error has occurred. Thereafter, a word (302) is formed on the network trunk line, the word being made up of two bytes including the data byte and a second byte having a parity bit. The parity bit is set equal to the parity of the word if it is determined that a signal transmission error has not occurred and the parity bit is set opposite of the parity of the word if it is determined that a signal transmission error has occurred.

Loading the Abstract Image...

First Claim