Transporting synchronization channel information across a packet network

• US 20060268832A1
• Filed: 05/26/2005
• Published: 11/30/2006
• Est. Priority Date: 05/26/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Mekala, Anantha R., Ogagan, George O.
• Granted Patent: US 7,627,004 B2
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: H04J 3/14 Monitoring arrangements for SDH/SONET rings H04J3/085
• CPC Class Codes: H04J 3/1623 Plesiochronous digital hierarchy [PDH]
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/9042 Separate storage for different parts of the packet, e.g. header and payload
• CPC Class Codes: H04Q 3/0045 involving hybrid, i.e. a mixture of public and private, or multi-vendor systems

Abstract

A technique for preserving information contained in a synchronization channel of a Time Division Multiplexing (TDM) frame across a packet network. Information contained in the synchronization channel of TDM frames is transferred over the packet network by a first gateway device that received the TDM frames. A second gateway device receives the synchronization channel information and places the information in one or more TDM frames. The TDM frames are transferred onto the TDM network.

Claims

1. A method for preserving data contained in a synchronization channel of time division multiplexing (TDM) frames across a packet network, the method comprising:

receiving a TDM frame;

extracting data contained in the synchronization channel of the received TDM frame; and

transferring the extracted data onto the packet network.

2. A method as defined in claim 1 further comprising:

placing the extracted data into a packet; and

transferring the packet onto the packet network.

3. A method as defined in claim 2 wherein the packet is an Asynchronous Transfer Mode (ATM) Adaptation Layer 2 (AAL2) packet.

4. A method as defined in claim 2 further comprising:

(a) generating a cyclic redundancy check (CRC) for the packet; and

(b) placing the CRC into the packet.

5. A method as defined in claim 2 further comprising:

(a) generating a flag that indicates which data contained in the synchronization channel are present in the packet; and

(b) placing the flag into the packet.

6. A method as defined in claim 1 wherein the extracted data is transferred onto the packet network after an amount of extracted data has been placed in a buffer.

7. A method as defined in claim 1 wherein the extracted data is transferred onto the packet network after a predetermined amount of time has elapsed.

8. A method as defined in claim 1 wherein the TDM frame is an E1 frame.

9. A method as defined in claim 1 further comprising;

placing the extracted data into one or more data frames; and

transferring the data frames onto the packet network.

10. A method as defined in claim 9 wherein the data frames are Service Specific Transmission Error Detection (SSTED) frames.

11. A method for processing packets containing synchronization channel data of one or more time division multiplexing (TDM) frames, the method comprising:

receiving a packet containing synchronization channel data of a first TDM frame;

extracting the synchronization channel data from the packet; and

placing the extracted data into a synchronization channel of a second TDM frame.

12. A method as defined in claim 11 further comprising:

transferring the second TDM frame onto a TDM network.

13. A method as defined in claim 11 wherein the first and second frames are E1 frames.

14. An apparatus for preserving data contained in a synchronization channel of time division multiplexing (TDM) frame across a packet network, the apparatus comprising:

a TDM interface configured to receive the TDM frame;

an extractor configured to extract the data contained in the synchronization channel of the received TDM frame; and

an encapsulator configured to;

(a) place the extracted data into a packet, and

(b) forward the packet onto the packet network.

15. An apparatus as defined in claim 14 further comprising:

a buffer accessible to the encapsulator and configured to store the extracted data.

16. An apparatus as defined in claim 15 wherein the packet is forwarded after a predetermined amount of extracted data has been stored in the buffer.

17. An apparatus as defined in claim 14 wherein the packet is forwarded after a predetermined period of time has elapsed.

18. An apparatus for transferring data contained in a synchronization channel of time division multiplexing (TDM) frames onto a packet network, the node comprising:

means for receiving a TDM frame;

means for extracting the data contained in the synchronization channel of the received TDM frame;

means for placing the extracted data into a packet; and

means for forwarding the packet onto the packet network.

19. A system for preserving data contained in a synchronization channel of time division multiplexing (TDM) frames across a packet network, the system comprising:

a first node configured to;

(a) receive a first TDM frame,

(b) extract the data contained in the synchronization channel of the received first TDM frame,

(c) place the extracted synchronization channel data into a packet, and

(d) forward the packet onto the packet network; and

a second node configured to;

(a) receive the packet,

(b) extract the synchronization channel data from the packet, and

(c) place the extracted data into a synchronization channel of a second TDM frame.

20. A computer-readable medium comprising computer-executable instructions for:

receiving a time division multiplexing (TDM) frame containing data in its synchronization channel;

extracting the data contained in the synchronization channel of the received TDM frame;

placing the extracted data into a packet; and

forwarding the packet onto a packet network.