Methods for dynamically assigning link addresses and logical network addresses

• US 6,208,656 B1
• Filed: 04/11/1997
• Issued: 03/27/2001
• Est. Priority Date: 01/17/1997
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: Hrastar, Scott E., Smith, George Horkan
• Primary Examiner(s): NGO, RICKY QUOC
• Application Number:
  US08/843,061
• Time in Patent Office: 1,446 Days
• Field of Search: 370/392, 370/400, 370/401, 370/409, 370/465, 370/480, 370/431, 370/432, 370/438, 370/437, 370/439, 370/468, 370/475, 348/522, 348/6, 348/7, 375/222, 455/3.1, 455/4.1, 455/5.1
• US Class Current: 370/401
• CPC Class Codes: H04H 20/79 using downlink of the CATV systems, e.g. audio broadcast via CATV network
• CPC Class Codes: H04H 60/84 which are fixed telephone networks
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 12/2856 Access arrangements, e.g. Internet access asynchronous transfer mode networks H04L12/5601; broadband local area networks H04L12/2801; optical access or distribution networks H04Q11/0067; access to open networks H04L12/5691; digital subscriber line end-user equipment and bit-level processing of data on a PSTN-based network H04M11/00; home network gateways H04L12/2834; wireless access networks H04W
• CPC Class Codes: H04L 12/2863 Arrangements for combining access network resources elements, e.g. channel bonding modem pooling H04L25/14; routing of packets H04L45/00; multichannel or multilink protocols H04L69/14
• CPC Class Codes: H04L 12/2872 Termination of subscriber connections
• CPC Class Codes: H04L 12/2874 Processing of data for distribution to the subscribers
• CPC Class Codes: H04L 12/5692 Selection among different networks
• CPC Class Codes: H04L 2101/604 Address structures or formats
• CPC Class Codes: H04L 2101/622 Layer-2 addresses, e.g. medium access control [MAC] addresses
• CPC Class Codes: H04L 41/0213 Standardised network management protocols, e.g. simple network management protocol [SNMP]
• CPC Class Codes: H04L 41/0663 Performing the actions predefined by failover planning, e.g. switching to standby network elements
• CPC Class Codes: H04L 41/0677 Localisation of faults
• CPC Class Codes: H04L 61/50 Address allocation
• CPC Class Codes: H04L 61/5007 Internet protocol [IP] addresses
• CPC Class Codes: H04L 61/5014 using dynamic host configuration protocol [DHCP] or bootstrap protocol [BOOTP]
• CPC Class Codes: H04L 61/5061 Pools of addresses
• CPC Class Codes: H04L 63/08 for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04N 21/25816 : involving client authentication restricting access to computer systems by authenticating users using a predetermined code G06F21/33; cryptographic authentication protocols H04L9/32; networks authentication protocols H04L63/08; authentication in wireless network security H04W12/06
• CPC Class Codes: H04N 21/42676 : for modulating an analogue carrier signal to encode digital information or demodulating it to decode digital information, e.g. ADSL or cable modem
• CPC Class Codes: H04N 21/6118 : involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/6168 : involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/17309 : Transmission or handling of upstream communications

Abstract

An asymmetrical network for coupling customer-premises Internet hosts such as personal computers to the Internet. The head end of a CATV system has a high-bandwidth connection to the Internet. The down link connecting the personal computers to the Internet is the cables provided by the CATV system; the up link is a telephone connection to the head end. A router is connected to the down link by means of an RF modem, to the up link by means of an analog modem, and to a LAN which is connected to the Pcs. The router routes IP packets for the hosts that are received on the CATV cable to the hosts via the LAN; it routes IP packets from the hosts that are destined for the Internet to the head end via the telephone line. The asymmetrical network conserves IP addresses and addresses on the CATV cable by dynamically allocating the IP addresses for an RF modem'"'"'s hosts and an address on the CATV cable for the RF modem in response to a request made by the RF modem via the telephone line. It further saves IP addresses by assigning a non-unique IP address to the router for use inside the LAN. When the CATV system fails, the asymmetrical network automatically begins to use the telephone line as both the up link and the down link, and when the CATV system is restored, the asymmetrical network automatically returns to using the CATV cable as the down link and the telephone line as the up link. A further feature of the asymmetrical network is that the head end components and the RF modem have IP addresses, so that standard TCP/IP protocols can be used to control the asymmetrical network.

Claims

1. A method employed in an RF (radio frequency) modem for dynamically assigning a link address on an RF cable connection for said RF modem, the link address being used for communication of messages on said RF cable connection, the method comprising the steps performed in said RF modem of:

requesting assignment via a bidirectional link for said link address by sending information including at least one specifier for said RF cable connection to a head end; and

receiving from said head end via the bidirectional link information including said link address, said link address uniquely identifying said RF modem within said RF cable connection.

2. The method of claim 1 wherein said RF cable connection is a communications medium which operates using a link-level protocol.

3. The method of claim 1 wherein said bidirectional link is a communications medium which operates using a link-level protocol.

4. The method of claim 1, wherein said RF cable connection has a plurality of channels multiplexed onto said RF cable connection so that a channel of said plurality of channels is separated by frequency from each other channel of said plurality of channels.

5. The method of claim 4, wherein a plurality of frames are multiplexed onto said channel so that each frame of said plurality of frames only uses said channel for a portion of time that said channel can be used.

6. The method of claim 5, wherein a fixed number of packets, N, are multiplexed into a first frame of said plurality of frames so that an i^th packet of said fixed number of packets is always at a static, computably fixed bit position relative to a header at the start of said first frame, and given that i is an integer between 0 and N+1(0<

i<

N+1).

7. The method of claim 6, wherein a packet of said fixed number of packets comprises a packet payload and a packet header, said packet header comprising a header ID number.

8. The method of claim 7, wherein said link address is used by said RF modem to select said packet payload on said RF cable connection that said RF modem should process, said link address further comprising:

a channel ID used to uniquely select said channel utilized in said RF cable connection by said RF modem;

a pipe ID used to uniquely select a static, computably fixed bit position within said first frame where said RF modem should examine first information communicated in said first frame; and

a link ID used to uniquely identify said packet within said first information communicated in said first frame by matching said link ID to said header ID number, said packet comprising said packet payload that said RF modem should process.

9. The method of claim 1, wherein said bidirectional link is an analog, telephone line connection to a PSTN (Public Switched Telephone Network).

10. The method of claim 1, wherein said at least one specifier for said RF cable connection is a stream ID (STRID) that allows said head end to uniquely identify said RF cable connection that said RF modem is connected to, and allows said head end to assign said link address to said RF modem.

11. The method of claim 1, wherein said step of requesting said assignment by sending information, including said at least one specifier for said RF cable connection, and the step of receiving information, including said link address, are accomplished using a DHCP (Dynamic Host Configuration Protocol).

12. The method of claim 11, wherein at least one vendor-encapsulated-option of a DHCP datagram is used to convey said at least one specifier for said RF cable connection.

13. A method employed in a first RF (radio frequency) modem, the method for obtaining an automated, dynamic assignment of a first link address, the method comprising the steps performed in the first RF modem of:

requesting assignment of the first link address for the first RF modem, the assignment request made by sending first information to at least one server, the first RF modem being one of a plurality of RF modems that are connected to a data network, the data network comprising an RF cable connection, the plurality of RF modems being connected to the RF cable connection, the first link address being one of a plurality of link addresses for the RF cable connection, each RF modem of the plurality of RF modems being uniquely identified in the RF cable connection responsive to being associated with at least one link address of the plurality of link addresses for the RF cable connection; and

receiving second information from the at least one server, the second information comprising the first link address, the first RF modem being associated with the first link address to uniquely identify the first RF modem in the RF cable connection.

14. The method of claim 13, wherein the at least one server is connected to the data network.

15. The method of claim 13, wherein the plurality of link addresses for the RF cable connection comprise a plurality of dynamically-assigned link addresses, the plurality of dynamically-assigned link addresses comprising the first link address, the at least one server capable of managing dynamic assignment of the plurality of dynamically-assigned link addresses.

16. The method of claim 13, wherein at any point in time each link address of the plurality of link addresses for the RF cable connection is capable of being associated with only one RF modem of the plurality of RF modems, each link address of the plurality of link addresses for the RF cable connection having a uniquely different value from each other link address of the plurality of link addresses for the RF cable connection.

17. The method of claim 13, wherein, the data network is connected between a head end and each RF modem of the plurality of RF modems and wherein the RF cable connection is connected between the head end and each RF modem of the plurality of RF modems.

18. The method of claim 17, wherein the data network further comprises at least one PSTN (Public Switched Telephone Network) connection, the at least one PSTN connection connected between the head end and each RF modem of the plurality of RF modems.

19. The method of claim 17, wherein the first information is conveyed between the first RF modem and the at least one server through the data network and wherein the second information is conveyed between the first RF modem and the at least one server through the data network.

20. The method of claim 19, wherein the RF cable connection comprises at least one RF link.

21. The method of claim 20, wherein the RF cable connection further comprises at least one modulator and at least one combiner.

22. The method of claim 20, wherein each RF modem of the plurality of RF modems is connected to the at least one RF link.

23. The method of claim 22, wherein the at least one RF link utilizes a link level protocol to convey information.

24. The method of claim 23, wherein the link level protocol is a protocol in which each RF modem of the plurality of RF modems is uniquely identified in the RF cable connection responsive to being associated with at least one link address of the plurality of link addresses for the RF cable connection.

25. The method of claim 23, wherein the first link address is utilized in communicating at least one first message with the first RF modem of the plurality of RF modems, the at least one first message being conveyed through the at least one RF link using the link level protocol, the at least one first message comprising third information communicated above the link level protocol with the first RF modem.

26. The method of claim 25, wherein a second RF modem of the plurality of RF modems is associated with a second link address of the plurality of link addresses to uniquely identify the second RF modem in the RF cable connection, the second link address being utilized in communicating at least one second message with a second RF modem of the plurality of RF modems, the at least one second message being conveyed through the at least one RF link using the link level protocol, the at least one second message comprising fourth information communicated above the link level protocol with the second RF modem.

27. The method of claim 26, wherein the third information communicated above the link level protocol in the first message comprises a first at least one IP datagram and wherein the fourth information communicated above the link level protocol in the second message comprises a second at least one IP datagram.

28. The method of claim 26, wherein the at least one RF link is at least one physical link.

29. The method of claim 28, wherein the RF cable connection has a plurality of channels multiplexed onto the at least one RF link so that each channel of the plurality of channels is separated by frequency from each other channel of the plurality of channels.

30. The method of claim 29, wherein a channel of the plurality of channels is shared by the first RF modem and the second RF modem, the channel being shared so that communication with the first RF modem of the plurality of RF modems occurs during a first portion of time that the channel is capable of being used, the communication with the first RF modem communicating the third information above the link level protocol, the channel further being shared so that communication with the second RF modem of the plurality of RF modems occurs during a second portion of time that the channel is capable of being used, the communication with the second RF modem communicating the fourth information above the link level protocol, the first portion of time being different from the second portion of time.

31. The method of claim 30, wherein a plurality of frames are multiplexed onto the channel so that a frame of the plurality of frames only uses the channel for a third portion of time that the channel is capable of being used, the third portion of time comprising the first portion of time and the second portion of time.

32. The method of claim 31, wherein the first portion of time is at a first position within the third portion of time, the first position being determinable through a first computation, and wherein the second portion of time is at a second position within the third portion of time, the second position being determinable through a second computation.

33. The method of claim 32, wherein the first link address comprises a first identifier for the channel of the plurality of channels and further comprises a second identifier used in the first computation for determining the first position of the first portion of time within the third portion of time.

34. The method of claim 33, wherein the first computation comprises multiplying the second identifier by a fixed amount of time and adding an offset amount related to a header of the frame.

35. The method of claim 32, wherein the second link address comprises a first identifier for the channel of the plurality of channels and further comprises a second identifier used in the second computation for determining the second position of the second portion of time within the third portion of time.

36. The method of claim 35, wherein the second computation comprises multiplying the second identifier by a fixed amount of time and adding an offset amount related to a header of the frame.

37. The method of claim 30, wherein the first link address comprises a first identifier for the channel of the plurality of channels and further comprises a second identifier, the second identifier identifying fifth information in the first portion of time, the identifying comprising a first evaluation of a relationship between the second identifier and the fifth information conveyed on the at least one RF link utilizing the link level protocol, the fifth information comprising the third information.

38. The method of claim 37, wherein the first evaluation comprises a comparison of the second identifier with the fifth information conveyed on the at least one RF link utilizing the link level protocol.

39. The method of claim 30, wherein second link address comprises a first identifier for the channel of the plurality of channels and further comprises a second identifier, the second identifier identifying sixth information in the second portion of time, the identifying comprising a second evaluation of a relationship between the second identifier and the sixth information conveyed on the at least one RF link utilizing the link level protocol, the sixth information comprising the fourth information.

40. The method of claim 39, wherein the second evaluation comprises a comparison of the second identifier with the sixth information conveyed on the at least one RF link utilizing the link level protocol.

41. An apparatus for obtaining an automated, dynamic assignment of a first link address for a first RF (radio frequency) modem, the apparatus comprising:

logic configured to request assignment of the first link address for the first RF modem, the assignment request made by sending first information to at least one server, the first RF modem being one of a plurality of RF modems that are connected to a data network, the data network comprising an RF cable connection, the plurality of RF modems being connected to the RF cable connection, the first link address being one of a plurality of link addresses for the RF cable connection, each RF modem of the plurality of RF modems being uniquely identified in the RF cable connection responsive to being associated with at least one link address of the plurality of link addresses for the RF cable connection; and

logic configured to receive second information from the at least one server, the second information comprising the first link address, the first RF modem being associated with the first link address to uniquely identify the first RF modem in the RF cable connection.

42. The apparatus of claim 41, wherein the at least one server is connected to the data network.

43. The apparatus of claim 41, wherein the plurality of link addresses for the RF cable connection comprise a plurality of dynamically-assigned link addresses, the plurality of dynamically-assigned link addresses comprising the first link address, the at least one server capable of managing dynamic assignment of the plurality of dynamically-assigned link addresses.

44. The apparatus of claim 41, wherein at any point in time each link address of the plurality of link addresses for the RF cable connection is capable of being associated with only one RF modem of the plurality of RF modems, each link address of the plurality of link addresses for the RF cable connection having a uniquely different value from each other link address of the plurality of link addresses for the RF cable connection.

45. The method of claim 41, wherein, the data network is connected between a head end and each RF modem of the plurality of RF modems and wherein the RF cable connection is connected between the head end and each RF modem of the plurality of RF modems.

46. The apparatus of claim 41, wherein the data network further comprises at least one PSTN (Public Switched Telephone Network) connection, the at least one PSTN connection connected between the head end and each RF modem of the plurality of RF modems.

47. The method of claim 45, wherein the first information is conveyed between the first RF modem and the at least one server through the data network and wherein the second information is conveyed between the first RF modem and the at least one server through the data network.

48. The apparatus of claim 47, wherein the RF cable connection comprises at least one RF link.

49. The apparatus of claim 48, wherein the RF cable connection further comprises at least one modulator and at least one combiner.

50. The apparatus of claim 48, wherein each RF modem of the plurality of RF modems is connected to the at least one RF link.

51. The apparatus of claim 50, wherein the at least one RF link utilizes a link level protocol to convey information.

52. The apparatus of claim 51, wherein the link level protocol is a protocol in which each RF modem of the plurality of RF modems is uniquely identified in the RF cable connection responsive to being associated with at least one link address of the plurality of link addresses for the RF cable connection.

53. The apparatus of claim 51, wherein the first link address is utilized in communicating at least one first message with the first RF modem of the plurality of RF modems, the at least one first message being conveyed through the at least one RF link using the link level protocol, the at least one first message comprising third information communicated above the link level protocol with the first RF modem.

54. The apparatus of claim 53, wherein a second RF modem of the plurality of RF modems is associated with a second link address of the plurality of link addresses to uniquely identify the second RF modem in the RF cable connection, the second link address being utilized in communicating at least one second message with a second RF modem of the plurality of RF modems, the at least one second message being conveyed through the at least one RF link using the link level protocol, the at least one second message comprising fourth information communicated above the link level protocol with the second RF modem.

55. The apparatus of claim 54, wherein the third information communicated above the link level protocol in the first message comprises a first at least one IP datagram and wherein the fourth information communicated above the link level protocol in the second message comprises a second at least one IP datagram.

56. The apparatus of claim 54, wherein the at least one RF link is at least one physical link.

57. The apparatus of claim 56, wherein the RF cable connection has a plurality of channels multiplexed onto the at least one RF link so that each channel of the plurality of channels is separated by frequency from each other channel of the plurality of channels.

58. The apparatus of claim 57, wherein a channel of the plurality of channels is shared by the first RF modem and the second RF modem, the channel being shared so that communication with the first RF modem of the plurality of RF modems occurs during a first portion of time that the channel is capable of being used, the communication with the first RF modem communicating the third information above the link level protocol, the channel further being shared so that communication with the second RF modem of the plurality of RF modems occurs during a second portion of time that the channel is capable of being used, the communication with the second RF modem communicating the fourth information above the link level protocol, the first portion of time being different from the second portion of time.

59. The apparatus of claim 58, wherein a plurality of frames are multiplexed onto the channel so that a frame of the plurality of frames only uses the channel for a third portion of time that the channel is capable of being used, the third portion of time comprising the first portion of time and the second portion of time.

60. The apparatus of claim 59, wherein the first portion of time is at a first position within the third portion of time, the first position being determinable through a first computation, and wherein the second portion of time is at a second position within the third portion of time, the second position being determinable through a second computation.

61. The apparatus of claim 60, wherein the first link address comprises a first identifier for the channel of the plurality of channels and further comprises a second identifier used in the first computation for determining the first position of the first portion of time within the third portion of time.

62. The apparatus of claim 61, wherein the first computation comprises multiplying the second identifier by a fixed amount of time and adding an offset amount related to a header of the frame.

63. The apparatus of claim 60, wherein the second link address comprises a first identifier for the channel of the plurality of channels and further comprises a second identifier used in the second computation for determining the second position of the second portion of time within the third portion of time.

64. The apparatus of claim 63, wherein the second computation comprises multiplying the second identifier by a fixed amount of time and adding an offset amount related to a header of the frame.

65. The apparatus of claim 58, wherein the first link address comprises a first identifier for the channel of the plurality of channels and further comprises a second identifier, the second identifier identifying fifth information in the first portion of time, the identifying comprising a first evaluation of a relationship between the second identifier and the fifth information conveyed on the at least one RF link utilizing the link level protocol, the fifth information comprising the third information.

66. The apparatus of claim 65, wherein the first evaluation comprises a comparison of the second identifier with the fifth information conveyed on the at least one RF link utilizing the link level protocol.

67. The apparatus of claim 58, wherein second link address comprises a first identifier for the channel of the plurality of channels and further comprises a second identifier, the second identifier identifying sixth information in the second portion of time, the identifying comprising a second evaluation of a relationship between the second identifier and the sixth information conveyed on the at least one RF link utilizing the link level protocol, the sixth information comprising the fourth information.

68. The apparatus of claim 67, wherein the second evaluation comprises a comparison of the second identifier with the sixth information conveyed on the at least one RF link utilizing the link level protocol.