Transparent multiplexer/demultiplexer

• US 5,841,760 A
• Filed: 04/24/1997
• Issued: 11/24/1998
• Est. Priority Date: 04/24/1997
• Status: Expired due to Term

• Current Assignee: Ciena Corporation
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Solheim, Alan Glen, Gagnon, Ronald J., Wight, Mark Stephen, Tatar, Mohammed Ismael, Martin, David Wright, Nicholson, David John, Armstrong, Timothy James
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): Sam, Phirin
• Application Number:
  US08/847,526
• Time in Patent Office: 579 Days
• Field of Search: 370/319, 370/337, 370/501, 370/503, 370/907, 370/535, 370/916, 370/539, 370/538, 370/541, 370/505, 370/536, 370/557, 370/543, 359/118, 359/119, 359/114, 359/115, 359/109, 359/123, 359/128, 359/135, 359/136, 359/139, 359/147
• US Class Current: 370/242
• CPC Class Codes: H04J 2203/0057 Operations, administration and maintenance [OAM]
• CPC Class Codes: H04J 2203/0089 Multiplexing, e.g. coding, scrambling, SONET
• CPC Class Codes: H04J 3/085 for ring networks, e.g. SDH/SONET rings, self-healing rings, meashed SDH/SONET networks
• CPC Class Codes: H04J 3/1611 Synchronous digital hierarchy [SDH] or SONET H04J3/1664 takes precedence for interactions with OTN

Abstract

A configuration for a SONET transport node comprises a pair of transparent mux/demuxs provided at two sites and connected over a high rate span. The T-Muxs provide continuity of all tribs and maintain a lower bit rate linear or ring system through the higher bit rate span. The lower bit rate linear or ring system operates as if it were directly connected without the higher bit rate midsection. For the forward direction of the traffic, the T-Mux comprises a multi-channel receiver for receiving the trib signals and providing for each trib signal a trib SPE and a trib OH. The trib SPEs are multiplexed into a supercarrier SPE and the trib OHs signals are processed to generate a supercarrier OH. A supercarrier transmitter maps the supercarrier SPE and the supercarrier OH into a supercarrier signal and transmits same over the high rate span. Reverse operations are effected for the reverse direction of traffic. With this invention, an entire ring system does not have to be upgraded to a higher line rate due to fiber exhaust on a single span. The invention is particularly applicable to OC-48/OC-12/OC-3 linear and ring networks and the high rate span could be an OC-192 line.

Claims

1. A transparent multiplexer/demultiplexer (T-Mux) for transparently transporting a plurality (K) of trib signals between a first and a second site over a high rate span, each trib signal travelling on a corresponding trib network, comprising:

a multi-channel receiver for receiving a plurality of forward trib signals and delineating each said forward trib input signal into a forward trib data signal and a forward trib operation, administration, maintenance and provisioning (OAM&

P) signal;

means for multiplexing all said forward trib data signals into a forward supercarrier data signal;

means for processing all said forward trib OAM&

P signals and generating a forward supercarrier OAM&

P signal; and

a supercarrier transmitter for mapping said forward supercarrier data signal and said forward supercarrier OAM&

P signal into a forward supercarrier signal and transmitting same over said high rate span, where K is an integer selected according to the rate of each said tributary signal and the rate of said supercarrier signal.

2. A T-Mux as claimed in claim 1, further comprising:

a supercarrier receiver for receiving a reverse supercarrier signal over said high rate span and delineating same into a reverse supercarrier data signal and a reverse supercarrier OAM&

P signal;

means for demultiplexing said reverse supercarrier data signal into a plurality (K) of reverse trib data signals;

means for processing said reverse supercarrier OAM&

P signal into a like plurality (K) of reverse trib OAM&

P signals; and

a multi-channel transmitter for mapping each of said reverse trib data signals and a corresponding one of said reverse trib OAM&

P signals into a reverse trib signal and transmitting each said reverse trib signal over said corresponding network.

3. A transparent multiplexer/demultiplexer (T-Mux) comprising:

a plurality (K) of trib ports, a trib port for receiving a trib SONET OC-N signal from a corresponding trib network and separating same into N trib synchronous payload envelopes (SPE) and N trib overheads (OH), interleaved in a standardized order;

a supercarrier port for generating a supercarrier SONET OC-(N×

K) signal comprising a supercarrier SPE and a supercarrier OH;

a payload manager for multiplexing all said trib SPEs into said supercarrier SPE and providing same to said supercarrier port;

a supercarrier transmit OH processor for generating the bytes of said supercarrier OH and for providing same to said supercarrier port; and

a trib receive OH processor for distinctly manipulating the bytes of each said trib OH and providing same to said supercarrier transmit OH processor,

where K is an integer selected according to the rate of each said tributary signal and the rate of said supercarrier signal and N is the rate of any trib signal as defined by SONET/SDH standards.

4. A T-Mux as claimed in claim 3, further comprising a fault detector for determining a trib error count for each said trib signal and transmitting said trib error count to said supercarrier transmit OH processor.

5. A T-Mux as claimed in claim 3, further comprising a synchronization unit for synchronizing said supercarrier signal and said trib signals.

6. A T-Mux as claimed in claim 4, further comprising a path monitor for determining a path error count and providing said path error count to said fault detector.

7. A T-Mux as claimed in claim 3, wherein said trib receive OH processor comprises:

means for terminating bytes A1-2, J0, Z0, S1, Z1, and Z2 of each said trib OH; and

means for passing through unchanged bytes E1, F1, K1, K2, D4-D12, M1, and E1 of each said trib overhead OH to said supercarrier transmit OH processor.

8. A T-Mux as claimed in claim 7, wherein said trib receive OH processor further comprises means for providing error information on each said trib OH to said fault detector.

9. A T-Mux as claimed in claim 7, wherein said payload manager further comprises means for interchanging, within said supercarrier SPE, STS-1 SPE #1 of each said trib signal with a selected STS-1 SPE#n.

10. A T-Mux as claimed in claim 9, wherein said supercarrier transmit OH processor comprises:

means for generating bytes A1-2, J0, Z0, S1, Z1 and Z2 of said supercarrier OH and mapping same into a respective timeslot of STS-1 OH#1 of said supercarrier OH;

means for processing bytes H1-3 of each said trib OH to update the location pointer for each said STS-1 SPE into said supercarrier SPE; and

means for mapping the bytes of each said trib OH received from said trib receive OH processor into a respective timeslot of said supercarrier OH, according to order of the STS-1 SPEs into said supercarrier SPE.

11. A T-Mux as claimed in claim 10, wherein said supercarrier transmit OH processor further comprises means for processing said trib error count for each said trib signal to generate a line error message (Msg_k) and mapping said error message into the timeslot for the K2 byte of a STS-1 OH different from the STS-1s OH #1, #(1+N) to #(1+K×

N).

12. A T-Mux as claimed in claim 4, wherein said fault detector comprises:

means for processing bytes B1, B2 and B3 for each said trib overhead OH_k and providing said trib error count;

means for comparing said trib error count with a threshold;

means for declaring a signal degrade condition when said trib error count exceeds said threshold; and

means for providing an alarm signal when said trib error count indicates a hard failure condition.

13. A T-Mux as claimed in claim 11, wherein each said trib signal is an OC-48 signal, K=4 and said supercarrier signal is an OC-192 signal.

14. A T-Mux as claimed in claim 11, wherein each said trib signal is one of an OC-12 and an OC-3 signal, K=16 and said supercarrier signal is an OC-192 signal, a first trib port being unequipped.

15. A transparent multiplexer/demultiplexer (T-Mux) comprising:

a supercarrier port for receiving a supercarrier SONET OC-(N×

K) signal and separating same into a supercarrier SPE and a supercarrier OH, wherein said supercarrier SPE comprises N×

K component STS-1 SPEs and said supercarrier OH comprises N×

K corresponding STS-1 OHs, interleaved in a predetermined order;

a plurality (K) of trib ports, a trib port for receiving a trib SPE and a trib overhead (OH), generating therefrom a trib signal and transmitting same over a corresponding trib network;

a payload manager for de-multiplexing said supercarrier SPE into said trib SPEs and providing each trib SPE to a corresponding said trib port;

a trib transmit OH processor for generating the bytes of each said trib OH and providing same to a corresponding trib port; and

a supercarrier receive OH processor for distinctly manipulating the bytes of said supercarrier OH and for providing same to said trib transmit OH processor,

where K is an integer selected according to the rate of each said tributary signal and the rate of said supercarrier signal and N is the rate of any trib signal as defined by SONET/SDH standards.

16. A T-Mux as claimed in claim 15, further comprising a fault detector for receiving a trib error count for each said trib signal from said supercarrier transmit OH processor, calculating a bit error rate and transmitting said trib error rate to said trib transmit OH processor.

17. A T-Mux as claimed in claim 15, further comprising a synchronization unit for synchronizing said supercarrier signal and said trib signals.

18. A T-Mux as claimed in claim 15, further comprising a path monitor for receiving said bit error rate from said fault detector and providing same to said payload manager.

19. A T-Mux as claimed in claim 15, wherein said supercarrier receive OH processor comprises:

means for terminating bytes A1-2, J0, Z0, S1, Z1, and Z2 of said supercarrier OH; and

means for passing through unchanged bytes E1, F1, K1, K2, D4-D12, M1, and E1 of each said trib overhead OH to said supercarrier transmit OH processor.

20. A T-Mux as claimed in claim 19, wherein said payload manager further comprises means for returning, within said supercarrier SPE, said selected STS-1 SPE #n into said STS-1 SPE#1 of each said trib signal.

21. A T-Mux as claimed in claim 20, wherein said trib transmit OH processor comprises:

means for generating bytes A1-2, J0, Z0, S1, Z1 and Z2 of said trib OH and mapping same into a respective timeslot of each said trib OH;

means for processing bytes H1-3 of each said trib OH to update the location pointer for each said STS-1 SPE into said trib SPE;

means for mapping the bytes of each said trib OH received from said supercarrier receive OH processor into a respective timeslot of said trib OH, according to order of the STS-1 SPEs into said supercarrier SPE.

22. A T-Mux as claimed in claim 21, wherein said supercarrier receive OH processor further comprises means for extracting a line error message (Msg_k) for each said trib signal from the timeslot for the K2 byte of a selected STS-1 OH, different from the STS-1s OH #1, #(1+N) to #(1+K×

N), to generate said trib error count.

23. A T-Mux as claimed in claim 16, wherein said fault detector comprises:

means for processing each said trib error count to generate a bit error rate for each said trib overhead OH;

means for comparing said bit error rate with a threshold for each trib OH;

means for declaring a signal degrade condition when the trib error rate exceeds said threshold; and

means for providing an alarm signal when said trib error rate indicates a hard failure condition.

24. In a plurality (K) of trib systems for transporting trib signals of between a multitude of sites, all trib systems having in common a first and a second site, a method of carrying said trib signals between said first and second site with no change to the provisioning of any of said trib systems, comprising, at said first site, the steps of:

providing a first site rib port for each said trib system, and connecting each said first site trib port to a corresponding trib system T_k over a forward trib span;

at each said first site trib port, receiving a forward trib signal of a trib bit rate and multiplexing all said forward trib signals into a forward supercarrier signal of a supercarrier bit rate comprising OAM&

P information on each said forward trib signal and said forward supercarrier carrier signal;

providing a first site supercarrier port and connecting said first site supercarrier port to said second site over a high rate span and transmitting said forward supercarrier signal from said first site supercarrier port to said second site,

where K is an integer selected according to the rate of each said tributary signal.

25. A method as claimed in claim 24, wherein the bit rate of said supercarrier signal is substantially equal to the sum of the bit rates of all said trib signals.

26. A method as claimed in claim 24, further comprising, at said second site, the steps of:

at said second site, providing a second site supercarrier port and connecting said second site supercarrier port high rate span for receiving said forward supercarrier signal;

demultiplexing said forward supercarrier signal to obtain said forward trib signals, each said forward trib signal comprising said OAM&

P information; and

providing a second site trib port for each said trib system, and connecting each said second site trib port to said corresponding trib system over a trib span and transmitting each said forward trib signal back into said corresponding trib system.