Out-of-band embedded overhead architecture for a transmission network

An interface for formatting a first link having N channels to fit into a second link having N+M channels, wherein N and M are both integers, said first link transmitting first information, each of the first and second links comprising at least one primary data carrier link having a payload portion that normally transmits payload information and an overhead portion that normally transmits overhead information, said interface comprising:

• means for routing the first information to a set of N of the N+M channels of said second link;
• means for adding supplemental overhead information to be transmitted with the first information over said second link;
• and
• means for routing the supplemental overhead information to at least one added overhead channel chosen from the remaining M channels of said second link, said at least one added overhead channel occupying a payload portion of at least one primary rate carrier link of said second link;
• wherein said second link comprises means for transmitting a first sub-link and a second sub-link, wherein each of the first and second sub-links comprises a portion of the N channels of said first link, and wherein said interface further comprises means for generating said supplemental overhead information, said supplemental overhead information comprising signalling bits for controlling the routing of each of the first and second sub-links over said second link.

An interface for formatting a first link having N channels to fit into a second link having N+M channels, wherein N and M are both integers, said first link transmitting first information, each of the first and second links comprising at least one primary rate carrier link having a payload portion that normally transmits payload information and an overhead portion that normally transmits overhead information, said interface comprising:

• means for routing the first information to a set of N of the N+M channels of said second link;
• means for adding supplemental overhead information to be transmitted with the first information over said second link;
• and
• means for routing the supplemental overhead information to at least one added overhead channel chosen from the remaining M channels of said second link, said at least one added overhead channel occupying a payload portion of at least one primary rate carrier link of said second link;
• wherein a portion of said supplemental overhead information is compatible with at least one overhead bit of a SONET link.

An interface for formatting a first link having N channels to fit into a second link having N+M channels, wherein N and M are both integers, said first link transmitting first information, each of the first and second links comprising at least one primary rate carrier link having a payload portion that normally transmits payload information and an overhead portion that normally transmits overhead information, said interface comprising:

• means for routing the first information to a set of N of the N+M channels of said second link;
• means for adding supplemental overhead information to be transmitted with the first information over said second link;
• and
• means for routing the supplemental overhead information to at least one added overhead channel chosen from the remaining M channels of said second link, said at least one added overhead channel occupying a payload portion of at least one primary rate carrier link of said second link;
• wherein said supplemental overhead information comprises a path overhead byte having several overhead bits being used to convey overhead parameter information of the second link, and further wherein said means for routing the supplemental overhead information comprises means for processing said path overhead byte, said several overhead bits comprising a mode switching bit for switching the second link between several signalling modes.

A method for enhancing a first primary rate carrier link having N channels, comprising:

• emulating the first link with a second link having N+M channels, wherein both N and M are integers;
• and
• placing at least one supplemental overhead channel within at least one additionally available channel of the second link;
• wherein when said at least one supplemental overhead channel is placed within said at least one available channel of the second link, said supplemental overhead channel is routed to at least one out-of-band channel of a remaining set of M channels of the second link.

A method for enhancing a first primary rate carrier link having N channels, comprising:

• emulating the first link with a second link having N+M channels, wherein both N and M are integers;
• and
• placing at least one supplemental overhead channel within at least one additionally available channel of the second link;
• said method further comprising assigning one memory to be a first link memory and assigning another memory to be a second link memory, storing bytes of information received from the first link and bytes of information to be transmitted over the first link into said first link memory, and storing bytes of information received from the second link and bytes of information to be transmitted over the second link into said second memory, said method further comprising placing supplemental overhead information into said second link memory, and removing supplemental overhead information from said first link memory.