Router for which a logical network address which is not unique to the gateway address in default routing table entries

• US 6,249,523 B1
• Filed: 04/11/1997
• Issued: 06/19/2001
• 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): Patel, Ajit
• Assistant Examiner(s): Phunkulh, Bob A.
• Application Number:
  US08/840,304
• Time in Patent Office: 1,530 Days
• Field of Search: 370/352, 370/355, 370/356, 370/389, 370/392, 370/400, 370/401, 370/402, 370/403, 370/404, 370/405, 395/200.69, 395/200.7, 395/200.71, 395/200.72, 709/239
• 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. Standard TCP/IP protocols can be used to control the asymmetrical network.

Claims

1. An improved router system including a plurality of routers that are interconnected in a network, wherein each router of the plurality of routers has a plurality of links, wherein each router has at least one first link connected to at least one host and has at least one second link connected to the router system, and wherein each router routes packets received through the at least one first link of each router according to each packet'"'"'s logical network address, the improvement comprising:

a first router having a first logical network address associated with the at least one first link of the first router, the first router being enabled with respect to the first logical network address to forward data through the at least one first link of the first router and to forward data between the network and at least one first host connected to the at least one first link of the first router; and

a second router having a second logical network address associated with the at least one first link of the second router, the second router being enabled with respect to the second logical network address to forward data through the at least one first link of the second router to forward data and between the network and at least one second host connected to the at least one first link of the second router, wherein the second logical network address associated with the at least one first link of the second router is the same as, and concurrently enabled with, the first logical network address associated with the at least one first link of the first router, the second logical network address being visible only from the at least one first link of the second router and being used by the at least one second host for determining the second router'"'"'s link address in the at least one first link of the second router.

2. The improved router system of claim 1, wherein the first logical network address associated with the at least one first link of the first router is visible only from the at least one first link of the first router.

3. The improved router system of claim 1, wherein the first logical network address associated with the at least one first link of the first router is used by the at least one host connected to the at least one first link of the first router for determining the first router'"'"'s link address in the at least one first link of the first router.

4. The improved router system of claim 1, wherein the first logical network address associated with the at least one first link of the first router is an Internet Protocol address, and the second logical network address associated with the at least one first link of the second router is an Internet Protocol address.

5. The improved router system of claim 1, wherein the first router has a third logical network address associated with the at least one second link of the first router, and the second router has a fourth logical network address associated with the at least one second link of the second router.

6. The improved router system of claim 5, wherein the third logical network address associated with the at least one second link of the first router is an Internet Protocol address, and the fourth logical network address associated with the at least one second link of the second router is an Internet Protocol address.

7. The improved router system of claim 5, wherein the third logical network address associated with the at least one second link of the first router is different from the fourth logical network address associated with the at least one second link of the second router.

8. The improved router system of claim 1, wherein the at least one second host determines the second router'"'"'s link address in the at least one first link of the second router by using an address resolution protocol (ARP).

9. The improved router system of claim 8, wherein the at least one second host maintains an ARP cache that comprises a mapping between the second logical network address of the second router and second router'"'"'s link address in the at least one first link of the second router.

10. The improved router system of claim 3, wherein the at least one first host determines the first router'"'"'s link address in the at least one first link of the first router by using an address resolution protocol (ARP).

11. The improved router system of claim 10, wherein the at least one first host maintains an ARP cache that comprises a mapping between the first logical network address of the first router and first router'"'"'s link address in the at least one first link of the first router.

12. The improved router system of claim 1, wherein the at least one first host connected to the at least one first link of the first router is associated with a fifth logical network address, and the at least one second host connected to the at least one first link of the second router is associated with a sixth logical network address.

13. The improved router system of claim 12, wherein the fifth logical network address is an Internet Protocol address, and the sixth logical network address is an Internet Protocol address.

14. The improved router system of claim 12, wherein a first packet communicated from the at least one first host to the at least one second host has the fifth logical network address as its source logical network address and the sixth logical network address as its destination logical network address.

15. The improved router system of claim 14, wherein when the first packet is in the at least one first link of the first router, the first packet has the fifth logical network address as its source logical network address, and when the first packet is in the at least one first link of the second router, the first packet has the fifth logical network address as its source logical network address.

16. The improved router system of claim 14, wherein when the first packet is in the at least one first link of the first router, the first packet has the sixth logical network address as its destination logical network address, and when the first packet is in the at least one first link of the second router, the first packet has the sixth logical network address as its destination logical network address.

17. The improved router system of claim 14, wherein when the first packet is in the at least one first link of the first router, the first packet has the fifth logical network address as its source logical network address, and when the first packet is in the at least one first link of the second router, the first packet has the fifth logical network address as its source logical network address;

and wherein when the first packet is in the at least one first link of the first router, the first packet has the sixth logical network address as its destination logical network address, and when the first packet is in the at least one first link of the second router, the first packet has the sixth logical network address as its destination logical network address.

18. The improved router system of claim 12, wherein a second packet communicated from the at least one second host to the at least one first host has the sixth logical network address as its source logical network address and the fifth logical network address as its destination logical network address.

19. The improved router system of claim 18, wherein when the second packet is in the at least one first link of the second router, the second packet has the sixth logical network address as its source logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the sixth logical network address as its source logical network address.

20. The improved router system of claim 18, wherein when the second packet is in the at least one first link of the second router, the second packet has the fifth logical network address as its destination logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the fifth logical network address as its destination logical network address.

21. The improved router system of claim 18, wherein when the second packet is in the at least one first link of the second router, the second packet has the sixth logical network address as its source logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the sixth logical network address as its source logical network address;

and wherein when the second packet is in the at least one first link of the second router, the second packet as the fifth logical network address as its destination logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the fifth logical network address as its destination logical network address.

22. The improved router system of claim 1, wherein responsive to being enabled with respect to the first logical network address, the first router is capable of responding to an address resolution protocol (ARP) request from the at least one first host connected to the at least one first link of the first router, the response to the ARP request comprising a link address of the first router in the at least one first link of the first router.

23. The improved router system of claim 1, wherein responsive to being enabled with respect to the second logical network address, the second router is capable of responding to an address resolution protocol (ARP) request from the at least one second host connected to the at least one first link of the second router, the response to the ARP request comprising a link address of the second router in the at least one first link of the second router.

24. An improved router system, the router system comprising a plurality of routers that are interconnected in a network, wherein each router of the plurality of routers has a plurality of links, wherein each router has at least one first link, wherein each router routes packets received through the at least one first link of each router, and wherein each router is connected to a CATV head end by at least one second link, the improvement comprising:

a first router of the plurality of routers having a first logical network address, wherein the first logical network address of the first router is associated with at least one first link of the first router, the first router being enabled with respect to the first logical network address to forward data through the at least one first link of the first router and to forward data between the network and at least one first host connected to the at least one first link of the first router; and

a second router of the plurality of routers having a second logical network address that is the same as, and concurrently enabled with, the first logical network address of the first router, wherein the second logical network address of the second router is associated with at least one first link of the second router, the second router being enabled with respect to the second logical network address to forward data between the network and at least one second host connected to the at least one first link of the second router.

25. The improved router system of claim 24, wherein the first logical network address associated with the at least one first link of the first router is visible only from the at least one first link of the first router.

26. The improved router system of claim 24, wherein the first logical network address associated with the at least one first link of the first router is used by the at least one first host connected to the at least one first link of the first router for specifying the first router'"'"'s link address in the at least one first link.

27. The improved router system of claim 24, wherein the first logical network address associated with the at least one first link of the first router is an Internet Protocol address.

28. The improved router system of claim 24, wherein the second logical network address of the second router, which is the same as the first logical network address of the first link of the first router, is associated with the first link of the second router, the second router being further enabled with respect to the second logical network address to forward data through the at least one first link of the second router.

29. The improved router system of claim 28, wherein the second logical network address associated with the at least one first link of the second router is visible only from the at least one first link of the second router.

30. The improved router system of claim 28, wherein the second logical network address associated with the at least one first link of the second router is used by the at least one second host connected to the at least one first link of the second router for specifying the second router'"'"'s link address in the at least one first link of the second router.

31. The improved router system of claim 30, wherein the second logical network address associated with the at least one first link of the second router is an Internet Protocol address.

32. The improved router system of claim 24, wherein the first router has a third logical network address associated with the at least one second link of the first router, and the second router has a fourth logical network address associated with the second link of the second router.

33. The improved router system of claim 32, wherein the third logical network address associated with the at least one second link of the first router is an Internet Protocol address, and the fourth logical network address associated with the at least one second link of the second router is an Internet Protocol address.

34. The improved router system of claim 32, wherein the third logical network address associated with the second link of the first router is different from the fourth logical network address associated with the at least one second link of the second router.

35. The improved router system of claim 26, wherein the at least one first host determines the first router'"'"'s link address in the at least one first link of the first router by using an address resolution protocol (ARP).

36. The improved router system of claim 35, wherein the at least one first host maintains an ARP cache that comprises a mapping between the first logical network address of the first router and first router'"'"'s link address in the at least one first link of the first router.

37. The improved router system of claim 30, wherein the at least one second host determines the second router'"'"'s link address in the at least one first link of the second router by using an address resolution protocol (ARP).

38. The improved router system of claim 37, wherein the at least one second host maintains an ARP cache that comprises a mapping between the second logical network address of the second router and second router'"'"'s link address in the at least one first link of the second router.

39. The improved router system of claim 24, wherein the at least one first host connected to the at least one first link of the first router is associated with a fifth logical network address, and the at least one second host connected to the at least one first link of the second router is associated with a sixth logical network address.

40. The improved router system of claim 39, wherein the fifth logical network address is an Internet Protocol address, and the sixth logical network address is an Internet Protocol address.

41. The improved router system of claim 39, wherein a first packet communicated from the at least one first host to the at least one second host has the fifth logical network address as its source logical network address and the sixth logical network address as its destination logical network address.

42. The improved router system of claim 41, wherein when the first packet is in the at least one first link of the first router, the first packet has the fifth logical network address as its source logical network address, and when the first packet is in the at least one first link of the second router, the first packet has the fifth logical network address as its source logical network address.

43. The improved router system of claim 41, wherein when the first packet is in the at least one first link of the first router, the first packet has the sixth logical network address as its destination logical network address, and when the first packet is in the at least one first link of the second router, the first packet has the sixth logical network address as its destination logical network address.

44. The improved router system of claim 41, wherein when the first packet is in the at least one first link of the first router, the first packet has the fifth logical network address as its source logical network address, and when the first packet is in the at least one first link of the second router, the first packet has the fifth logical network address as its source logical network address;

and wherein when the first packet is in the at least one first link of the first router, the first packet has the sixth logical network address as its destination logical network address, and when the first packet is inthe at least one first link of the second router, the first packet has the sixth logical network as its destination logical network address.

45. The improved router system of claim 39, wherein a second packet communicated from the at least one second host to the at least one first host has the sixth logical network address as its source logical network address and the fifth logical network address as its destination logical network address.

46. The improved router system of claim 45, wherein when the second packet is in the at least one first link of the second router, the second packet has the sixth logical network address as its source logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the sixth logical network address as its source logical network address.

47. The improved router system of claim 45, wherein when the second packet is in the at least one first link of the second router, the second packet has the fifth logical network address as its destination logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the fifth logical network address as its destination logical network address.

48. The improved router system of claim 45, wherein when the second packet is in the at least one first link of the second router, the second packet has the sixth logical network address as its source logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the sixth logical network address as its source logical network address;

and wherein when the second packet is in the at least one first link of the second router, the second packet has the fifth logical network address as its destination logical network address, and when the second packet in in the at least one first link of the first router, the second packet has the fifth logical network address as its destination logical network address.

49. The improved router system of claim 24, wherein responsive to being enabled with respect to the first logical network address, the first router is capable of responding to an address resolution protocol (ARP) request from the at least one first host connected to the at least one first link of the first router, the response to the ARP request comprising a link address of the first router in the at least one first link of the first router.

50. The improved router system of claim 28, wherein the second logical network address is associated with the at least one first link of the second router, and wherein responsive to being enabled with respect to the second logical network address, the second router is capable of responding to an address resolution protocol (ARP) request from the at least one second host connected to the at least one first link of the second router, the response to the ARP request comprising a link address of the second router in the at least one first link of the second router.

51. A method for assigning the same logical network address to a plurality of routers in a router system, the routers being interconnected in a network, wherein each router of the router system has a plurality of links, the method comprising the steps of:

assigning a first logical network address to a first router for use on at least one first link of the first router, the first router being enabled with respect to the first logical network address to forward data through the at least one first link of the first router and to forward data between the network and at least one first host connected to the at least one first link of the first router; and

assigning a second logical network to a second route for use on at least one first link of the second router, wherein the assigned second logical network address of the second router is the same as, and concurrently enabled with, the assigned first logical network address of the first router, the second router being enabled with respect to the second logical network address to forward data through the at least one first link of the second router and to forward data between the network and at least one second host connected to the first link of the second router.

52. The method of claim 51, further comprising the step of:

transmitting the assigned second logical network address to the second router through a second link connected to the router.

53. The method of claim 51, further comprising the step of:

receiving at a CATV head end at least one message through a second link from the second router, wherein each router of the plurality of routers has a second link, and wherein each router of the plurality of routers is connected to the CATV head end through its corresponding second link.

54. The method of claim 53, wherein the received at least one message is an Internet Protocol message.

55. The method of claim 54, wherein the first and second logical network addresses are Internet Protocol addresses.

56. The method of claim 54, wherein the Internet Protocol message includes a Dynamic Host Configuration Protocol (DHCP) message.

57. The method of claim 53, wherein the received at least one message from the second router is an authentication message.

58. The method of claim 53, further comprising step of:

transmitting at least one message from the CATV head end to the second router through the second link of the second router.

59. The method of claim 58, wherein the transmitted at least one message from the CATV head end is an Internet Protocol message.

60. The method of claim 58, wherein the Internet Protocol message includes a Dynamic Host Configuration Protocol (DHCP) message.

61. The method of claim 58, wherein the Internet Protocol message includes an Internet Protocol address for assignment to the second router as the second logical network address.

62. The method of claim 51, wherein the at least one first host connected to the at least one first link of the first router is associated with a fifth logical network address, and the at least one second host connected to the at least one first link of the second router is associated with a sixth logical network address.

63. The method of claim 62, wherein the fifth logical network address is an Internet Protocol address, and the sixth logical network address is an Internet Protocol address.

64. The method of claim 63, wherein a first packet communicated from the at least one first host to the at least one second host has the fifth logical network address as its source logical network address and the sixth logical network address as its destination logical network address.

65. The improved royter system of claim 64, wherein when the first packet is in the at least one first link of the frst router, the first packet has the fifth logical network address as its source logical network addres, and when the first packet is in the at least one first link of the second router, the first packet has the fifth logical network address as its source logical network address.

66. The improved router system of claim 64, wherein when the first packet is in the at least one first link of the first router, the first packet has the sixth logical network address as its destination logical network address, and when the first packet is in the at least one first link of the second router, the first packet has the sixth logical network address as its source logical network address.

67. The improved router system of claim 64, wherein when the first packet is in the at least one first link of the first router, the first packet has the fifth logical network address as its source logical network addres, and when the first packet is in the at least one first link of the second router, the first packet has the fifth logical network address as its source logical network address;

and wherein when the first packet is in the at least one first link of the first router, the first packet has the sixth logical network address as its destination logical network address, and when the first packet is in the at least one first link of the second router, the first packet has the sixth logical network address as its source logical network address.

68. The improved router system of claim 62, wherein a second packet communicated from the at least one second host to the at least one first host has the sixth logical network address as its source logical network address and the fifth logical network address as its destination logical network address.

69. The improved router system of claim 68, wherein when the second packet is in the at least one first link of the second router, the second packet has the sixth logical network address as its source logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the sixth logical network address as its source logical network address.

70. The improved router system of claim 68, wherein when the second packet is in the at least one first link of the second router, the second packet has the fifth logical network address as its destination logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the fifth logical network address as its destination logical network address.

71. The improved router system of claim 68, wherein when the second packet is in the at least one first link of the second router, the second packet has the sixth logical network address as its source logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the sixth logical network address as its source logical network address;

and wherein when the second packet is in the at least one first link of the second router, the second packet has the fifth logical network address as its destination logical network address, and when the second packet is in the at least one first link of the first router, the second packet has the fifth logical network address as its destination logical network address.

72. The method of claim 51, wherein responsive to being enabled with respect to the first logical network address, the first router is capable of responding to an address resolution protocol (ARP) request from the at least one first host connected to the at least one first link of the first router, the response to the ARP request comprising a link address of the first router in the at least one first link of the first router.

73. The method of claim 51, wherein responsive to being enabled with respect to the second logical network address, the second router is capable of responding to an address resolution protocol (ARP) request from the at least one second host connected to the at least one first link of the second router, the response to the ARP request comprising a link address of the second router in the at least one first link of the second router.