Bridging and signalling subsystems and methods for private and hybrid communications systems including multimedia systems

• US 5,594,732 A
• Filed: 03/03/1995
• Issued: 01/14/1997
• Est. Priority Date: 03/03/1995
• Status: Expired due to Term

• Current Assignee: Cisco Systems, Inc.
• Original Assignee: Intecom Incorporated
• Inventors: Bell, Robert T., Platt, Richard B.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): TON, DANG T
• Application Number:
  US08/397,986
• Time in Patent Office: 683 Days
• Field of Search: 370/85.13, 370/85.12, 370/85.15, 370/85.6, 370/85.1, 370/60, 370/94.1, 370/94.2, 370/85.4, 370/94.3, 370/110.1, 370/68.1, 370/16, 370/16.1, 370/85.11 , 370/85.3, 370/43, 370/99, 370/108, 340/827, 340/825.05, 340/825.02, 371/8.1, 371/8.2, 371/11.1, 371/11.2, 371/37.7, 395/181.01, 395/181.02, 395/181, 395/183.01
• US Class Current: 370/401
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 2212/00 Encapsulation of packets
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04M 7/1245 where a network other than PSTN/ISDN interconnects two PSTN/ISDN networks
• CPC Class Codes: H04Q 11/0457 Connection protocols
• CPC Class Codes: H04Q 2213/13107 Control equipment for a part of the connection, distributed control, co-processing
• CPC Class Codes: H04Q 2213/13166 Fault prevention
• CPC Class Codes: H04Q 2213/13174 Data transmission, file transfer
• CPC Class Codes: H04Q 2213/13176 Common channel signaling, CCS7
• CPC Class Codes: H04Q 2213/13204 Protocols
• CPC Class Codes: H04Q 2213/13209 ISDN
• CPC Class Codes: H04Q 2213/13215 Code checking, CRC
• CPC Class Codes: H04Q 2213/13216 Code signals, frame structure
• CPC Class Codes: H04Q 2213/13248 Multimedia
• CPC Class Codes: H04Q 2213/1329 Asynchronous transfer mode, ATM
• CPC Class Codes: H04Q 2213/13337 Picturephone, videotelephony
• CPC Class Codes: H04Q 2213/13389 LAN, internet
• CPC Class Codes: H04Q 2213/13396 Signaling in general, in-band signalling

Abstract

A subsystem for communicating a private network signalling message over a packet network and bridges for communicating a Media Access Control (MAC) layer frame over an isochronous channel and for communicating an isochronous signalling frame over a nonisochronous network. The subsystem comprises: (1) an encapsulation circuit, coupled to a transmitting user station, capable of receiving the private network signalling message from the transmitting user station, the encapsulating circuit encapsulating the signalling message within, and adding source and destination addresses to, a routable protocol frame, the source and destination addresses corresponding to addresses of the transmitting user station and a particular receiving user station, the encapsulation circuit queuing the routable protocol frame for transmission over the packet network and (2) a de-encapsulation circuit, coupled to the particular receiving user station, capable of receiving the routable protocol frame, the de-encapsulation circuit extracting the signalling message from the routable protocol frame, the packet network thereby simulating a point-to-point connection between the transmitting and particular receiving user stations to effect node-to-node private network signalling therebetween.

Claims

1. A bridge for communicating a Media Access Control (MAC) layer frame over an isochronous signalling channel, comprising:

a frame reception and storage circuit coupled to a nonisochronous network, said frame reception and storage circuit capable of receiving said MAC layer frame from said nonisochronous network and storing said MAC layer frame in said frame reception and storage circuit; and

a frame encapsulation circuit coupling said frame reception and storage circuit and said isochronous signalling channel, said frame encapsulation circuit capable of encapsulating said stored MAC layer frame into a first frame and queuing said first frame for transmission over said isochronous signalling channel.

2. The bridge as recited in claim 1 wherein said MAC layer frame comprises a cyclical redundancy check (CRC), said frame encapsulation circuit stripping said CRC from said MAC layer frame.

3. The bridge as recited in claim 1 wherein said frame encapsulation circuit is further capable of (a) negotiating a larger maximum frame size by generating and receiving transmit identification (XID) messages over said isochronous signalling channel and (b), if said negotiating is unsuccessful, dividing said stored MAC layer frame into first and second segments, individually encapsulating said first and second segments into said first frame and a second frame, respectively, assigning a segment number to each of said first and second frames and queuing said first and second frames for transmission over said isochronous signalling channel.

4. The bridge as recited in claim 1 wherein said first frame comprises an address field and a control field.

5. The bridge as recited in claim 1 wherein said first frame is a Q.921 Unacknowledged Information frame.

6. The bridge as recited in claim 3 wherein said frame encapsulation circuit is further capable of receiving third and fourth frames from said isochronous signalling channel and de-encapsulating said third and fourth frames to form a MAC layer frame for transmission over said nonisochronous network.

7. The bridge as recited in claim 1 wherein said nonisochronous network is an Ethernet®

network.

8. The bridge as recited in claim 1 wherein said first frame comprises last segment and current segment length fields.

9. The bridge as recited in claim 1 wherein said first frame comprises a total MAC layer frame length field.

10. The bridge as recited in claim 1 wherein said MAC layer frame is an Ethernet®

frame.

11. A method of communicating a Media Access Control (MAC) layer frame over an isochronous signalling channel, comprising the steps of:

receiving said MAC layer frame from a nonisochronous network into a frame reception and storage circuit coupled to said nonisochronous network, said frame reception and storage circuit storing said MAC layer frame in said frame reception and storage circuit; and

encapsulating said stored MAC layer frame into a first frame with a frame encapsulation circuit coupling said frame reception and storage circuit and said isochronous signalling channel, said frame encapsulation circuit queuing said first frame for transmission over said isochronous signalling channel.

12. The method as recited in claim 11 wherein said MAC layer frame comprises a cyclical redundancy check (CRC), said method further comprising the step of stripping said CRC from said MAC layer frame with said frame encapsulation circuit.

13. The method as recited in claim 11 further comprising the steps of:

negotiating a larger maximum frame size by generating and receiving transmit identification (XID) messages over said isochronous signalling channel with said frame encapsulation circuit; and

if said step of negotiating is unsuccessful, dividing said stored MAC layer frame into first and second segments with said frame encapsulation circuit, said frame encapsulation circuit individually encapsulating said first and second segments into said first frame and a second frame, respectively, assigning a segment number to each of said first and second frames and queuing said first and second frames for transmission over said isochronous signalling channel.

14. The method as recited in claim 11 wherein said step of dividing comprises the step of adding an address field and a control field to said first frame.

15. The method as recited in claim 11 wherein said first frame is a Q.921 Unacknowledged Information frame.

16. The method as recited in claim 13 further comprising the step of receiving third and fourth frames from said isochronous signalling channel into said frame encapsulation circuit, said frame encapsulation circuit de-encapsulating said third and fourth frames to form a MAC layer frame for transmission over said nonisochronous network.

17. The method as recited in claim 11 wherein said nonisochronous network is an Ethernet®

network.

18. The method as recited in claim 11 wherein said step of dividing comprises the step of adding last segment and current segment length fields to said first frame.

19. The method as recited in claim 11 wherein said step of dividing comprises the step of adding a total MAC layer frame length field to said first frame.

20. The method as recited in claim 11 wherein said MAC layer frame is an Ethernet®

frame.

21. A bridge for communicating an isochronous signalling frame over a nonisochronous network, comprising:

a frame reception circuit coupled to an isochronous channel, said frame reception circuit capable of receiving said isochronous signalling frame from a subordinate device via said isochronous channel; and

a frame encapsulation circuit coupling said frame reception circuit and said nonisochronous network, said frame encapsulation circuit capable of encapsulating said isochronous signalling frame into a routable protocol frame and queuing said routable protocol frame for transmission over said nonisochronous network to a destination device, said nonisochronous network thereby capable of simulating a point-to-point connection between said subordinate device and said destination device.

22. The bridge as recited in claim 21 wherein said routable protocol is a User Datagram Protocol/Internet Protocol (UDP/IP) frame, said frame encapsulation circuit further capable of setting a source address field of said routable protocol frame equal to an address of said bridge and setting a destination address field equal to an address of said destination device.

23. The bridge as recited in claim 21 wherein said frame encapsulation circuit is further capable of receiving a subsequent routable protocol frame from said destination device via said nonisochronous network, said encapsulation circuit de-encapsulating a subsequent isochronous signalling frame from said routable protocol frame and queuing said isochronous signalling frame for transmission over said isochronous channel.

24. The bridge as recited in claim 21 wherein said routable protocol is a User Datagram Protocol/Internet Protocol (UDP/IP) frame, said frame encapsulation circuit further capable of Setting a UDP source port equal to a link number of said subordinary device.

25. The bridge as recited in claim 21 wherein said routable protocol is a User Datagram Protocol/Internet Protocol (UDP/IP) frame, said frame encapsulation circuit further capable of setting a UDP destination port equal to a well-known call processing port.

26. The bridge as recited in claim 21 wherein said isochronous signalling frame is a Q.921 signalling frame.

27. The bridge as recited in claim 21 wherein said nonisochronous network is an Ethernet®

network.

28. The bridge as recited in claim 21 wherein said frame reception circuit is further capable of validating a frame check sequence number of said isochronous signalling frame.

29. The bridge as recited in claim 21 wherein said reception circuit is coupled to a plurality of subordinate devices via a plurality of isochronous channels.

30. The bridge as recited in claim 21 wherein said nonisochronous network couples a plurality of bridges and destination devices, said nonisochronous network simulating a plurality of point-to-point isochronous channels coupling said plurality of bridges and destination devices.

31. A method of communicating an isochronous signalling frame over a nonisochronous network, comprising the steps of:

receiving said isochronous signalling frame from a subordinate device via an isochronous channel into a frame reception circuit coupled to said isochronous channel; and

encapsulating said isochronous signalling frame, with a frame encapsulation circuit coupling said frame reception circuit and said nonisochronous network, routable protocol frame and queuing said routable protocol frame for transmission over said nonisochronous network to a destination device, said nonisochronous network thereby capable of simulating a point-to-point connection between said subordinate device and said destination device.

32. The method as recited in claim 31 wherein said routable protocol frame is a User Datagram Protocol/Internet Protocol (UDP/IP) frame, said step of encapsulating further comprising the step of setting a source address field of said routable protocol frame equal to an address of said bridge and setting a destination address field equal to an address of said destination device with said frame encapsulation circuit.

33. The method as recited in claim 31 further comprising the step of receiving a subsequent routable protocol frame from said destination device via said nonisochronous network into said frame encapsulation circuit, said encapsulation circuit de-encapsulating a subsequent isochronous signalling frame from said routable protocol frame and queuing said isochronous signalling frame for transmission over said isochronous channel.

34. The method as recited in claim 31 wherein said routable protocol frame is a User Datagram Protocol/Internet Protocol (UDP/IP) frame, said step of encapsulating comprising the step of setting a UDP source port equal to a link number of said subordinate device.

35. The method as recited in claim 31 wherein said routable protocol frame is a User Datagram Protocol/Internet Protocol (UDP/IP) frame, said step of encapsulating comprising the step of setting a UDP destination port equal to a well-known call processing port.

36. The method as recited in claim 31 wherein said isochronous signalling frame is a Q.921 signalling frame.

37. The method as recited in claim 31 wherein said nonisochronous network is an Ethernet®

network.

38. The method as recited in claim 31 wherein said step of receiving comprises the step of validating a frame check sequence number of said isochronous signalling frame.

39. The method as recited in claim 31 wherein said method comprises the step of communicating with a plurality of subordinate devices via a plurality of isochronous channels with said reception circuit.

40. The method as recited in claim 31 wherein said method further comprises the step of communicating with a plurality of bridges and destination devices with said nonisochronous network, said nonisochronous network simulating a plurality of point-to-point isochronous channels coupling said plurality of bridges and destination devices.

41. A subsystem for communicating a private network signalling message over a packet network, comprising:

an encapsulation circuit, coupled to a transmitting user station, capable of receiving said private network signalling message from said transmitting user station, said encapsulation circuit encapsulating said signalling message within, and adding source and destination addresses to, a routable protocol frame, said source and destination addresses corresponding to addresses of said transmitting user station and a particular receiving user station, said encapsulation circuit queuing said routable protocol frame for transmission over said packet network; and

a de-encapsulation circuit, coupled to said particular receiving user station, capable of receiving said routable protocol frame, said de-encapsulation circuit extracting said signalling message from said routable protocol frame, said packet network thereby simulating a point-to-point connection between said transmitting and particular receiving user stations to effect node-to-node private network signalling therebetween.

42. The subsystem as recited in claim 41 wherein said routable protocol frame is a User Datagram Protocol/Internet Protocol (UDP/IP) frame.

43. The subsystem as recited in claim 41 wherein said private network signalling message is a Q.931 signalling message.

44. The subsystem as recited in claim 41 wherein said packet network comprises redundant backbones coupling said encapsulation circuit and said de-encapsulation circuit.

45. The subsystem as recited in claim 41 wherein said transmitting user station is capable of creating a user information path via an isochronous channel, said isochronous channel created on an Asynchronous Transfer Mode (ATM) network.

46. The subsystem as recited in claim 41 wherein said particular receiving user station is coupled to a second encapsulation circuit and said transmitting user station is coupled to a second de-encapsulation circuit, said particular receiving user station thereby capable of transmitting a subsequent signalling message to said transmitting user station in response to receipt of said signalling message from said transmitting user station.

47. The subsystem as recited in claim 41 wherein said packet network is free of a transit node.

48. The subsystem as recited in claim 41 wherein a user information path coupling said transmitting and receiving user stations is free of private network signalling messages.

49. The subsystem as recited in claim 41 wherein said packet network comprises a plurality of encapsulation circuit/de-encapsulation circuit pairs, each of said pairs functioning as an addressable node on said packet network.

50. The subsystem as recited in claim 41 wherein said encapsulation and de-encapsulation circuits comprise sequences of executable software instructions.

61. The subsystem as recited in claim 41 wherein said private network signalling message is a QSIG signalling message.

62. The subsystem as recited in claim 41 wherein said transmitting user station is capable of creating a user information path via an isochronous channel, said isochronous channel created on a Public Switched Digital Network (PSDN).

51. A method of communicating a private network signalling message over a packet network, comprising the steps of:

receiving said private network signalling message from a transmitting user station into an encapsulation circuit coupled to said transmitting user station, said encapsulation circuit encapsulating said signalling message within, and adding source and destination addresses to, a routable protocol frame, said source and destination addresses corresponding to addresses of said transmitting user station and a particular receiving user station, said encapsulation circuit queuing said routable protocol frame for transmission over said packet network; and

receiving said routable protocol frame into a de-encapsulation circuit coupled to a particular receiving user station, said de-encapsulation circuit extracting said signalling message from said routable protocol frame, said packet network thereby simulating a point-to-point connection between said transmitting and particular receiving user stations to effect node-to-node private network signalling therebetween.

52. The method as recited in claim 51 wherein said routable protocol frame is a User Datagram Protocol/Internet Protocol (UDP/IP) frame.

53. The method as recited in claim 51 wherein said private network signalling message is a Q.931 signalling message.

54. The method as recited in claim 51 wherein said packet network comprises redundant backbones coupling said encapsulation circuit and said de-encapsulation circuit.

55. The method as recited in claim 51 further comprising the step of creating a user information path via an isochronous channel with said transmitting user station, said isochronous channel created on an Asynchronous Transfer Mode (ATM) network.

56. The method as recited in claim 51 wherein said particular receiving user station is coupled to a second encapsulation circuit and said transmitting user station is coupled to a second de-encapsulation circuit, said method further comprising the step of transmitting a subsequent signalling message from said particular receiving user station to said transmitting user station in response to receipt of said signalling message from said transmitting user station.

57. The method as recited in claim 51 wherein said packet network is free of a transit node.

58. The method as recited in claim 51 wherein a user information path coupling said transmitting and receiving user stations is free of private network signalling messages.

59. The method as recited in claim 51 wherein said packet network comprises a plurality of encapsulation circuit/de-encapsulation circuit pairs, each of said pairs functioning as an addressable node on said packet network.

60. The method as recited in claim 51 wherein said encapsulation and de-encapsulation circuits comprise sequences of executable software instructions.

63. The method as recited in claim 51 wherein said private network signalling message is a QSIG signalling message.

64. The method as recited in claim 51 further comprising the step of creating a user information path via an isochronous channel with said transmitting user station, said isochronous channel created on a Public Switched Digital Network (PSDN).