Routing protocol based redundancy design for shared-access networks

• US 6,839,829 B1
• Filed: 01/18/2000
• Issued: 01/04/2005
• Est. Priority Date: 01/18/2000
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Woundy, Richard M., Thomas, Michael A., Daruwalla, Feisal, Roeck, Guenter E., Forster, James R.
• Primary Examiner(s): Pan, Daniel H.
• Application Number:
  US09/484,189
• Time in Patent Office: 1,813 Days
• Field of Search: 712/28, 712/29, 712/201, 712/225, 713/201, 709/220, 709/201, 709/223, 709/230, 709/245, 709/239, 714/43, 714/13, 714/20, 714/11, 714/10, 725/41, 725/109, 455/435, 370/217, 370/401, 370/402, 370/216, 370/443
• US Class Current: 712/28
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/586 of virtual routers
• CPC Class Codes: H04M 3/08 Indicating faults in circuits or apparatus
• CPC Class Codes: H04N 21/2404 Monitoring of server processing errors or hardware failure error or fault detection G06F11/07; monitoring in general G06F11/30
• CPC Class Codes: H04N 21/4788 communicating with other users, e.g. chatting arrangements for providing for computer conferences, e.g. chat rooms, to substation in data switching networks H04L12/1813; distributed application using peer-to-peer [P2P] networks H04L67/104
• 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 21/6402 Address allocation for clients address allocation in data networks H04L61/50
• CPC Class Codes: H04N 21/64322 IP
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

A protection CMTS is available to immediately service a cable modem should that modem'"'"'s service from a working CMTS fail for any reason. To speed the service transfer (cutover) from the working CMTS to the protection CMTS, the cable modem may preregister with the protection CMTS well before the cutover becomes necessary. The cable modem'"'"'s registration with both the working CMTS and the protection CMTS preferably employs a single IP address, so that the cable modem need not obtain a new IP address during cutover. While the cable modem may register with both the working CMTS and the protection CMTS, the devices are designed or configured so that only the working CMTS injects a host route for the cable modem into the appropriate routing protocol. Only after cutover to the protection CMTS does the protection CMTS inject its host route.

Claims

1. A method implemented on a working CMTS for providing redundancy to a cable network in which the working CMTS has a subnet of IP addresses for assigning to its cable modems and the working CMTS provides normal service to a cable modem and a protection CMTS, which has its own subnet of IP addresses, takes over service to the cable modem should service from the working CMTS become unavailable, the method comprising:

(a) participating in registration of the cable modem to allow servicing of the cable modem by the working CMTS; and

(b) obtaining an IP address for the cable modem, which IP address is obtained from an address space outside the subnet of the working CMTS,

wherein the IP address is used in communications with both the working CMTS and the protection CMTS,

whereby taking over service to the cable modem is performed without re-registering the cable modem or obtaining a new IP address for the cable modem and comprises requesting that the cable modem adjust at least one of the following parameters;

transmission power, transmission frequency, and transmission time slots.

2. The method of claim 1, wherein the working CMTS is a routing CMTS.

3. The method of claim 1, wherein the address space from which the IP address for the cable modem is obtained is outside of the subnet for the protection CMTS.

4. The method of claim 1, further comprising communicating the IP address for the cable modem to the protection CMTS.

5. The method of claim 1, further comprising injecting a host route to the cable modem into a routing protocol.

6. The method of claim 5, wherein injecting the host route comprises providing the host route to one or more aggregation routers servicing the cable network.

7. The method of claim 1, wherein participating in registration of the cable modem comprises specifying at least one of a transmission power, a transmission frequency, and transmission time slots at which the cable modem is to communicate with the working CMTS.

8. The method of claim 1, wherein participating in registration of the cable modem comprises participating in a process to assign the IP address for the cable modem.

9. The method of claim 8, wherein the process to assign the IP address for the cable modem is DHCP, and wherein the working CMTS obtains the IP address while performing a DHCP relay function.

10. The method claim 1, further comprising:

(c) determining that the working CMTS'"'"'s service to the cable modem has or will become unavailable; and

(d) notifying at least one of the cable modem and the protection CMTS that the cable modem should obtain service from the protection CMTS.

11. The method of claim 1, wherein the service provided to the cable modem includes telephony service.

37. The method of claim 1, wherein notifying at least one of the cable modem and the protection CMTS that the cable modem should obtain service from the protection CMTS comprises sending a downstream channel change request to the cable modem.

12. A computer program product comprising a machine readable medium on which is provided program instructions for performing a method implemented on a working CMTS, which method provides redundancy for a cable network in which the working CMTS has a subnet of IP addresses for assigning to its cable modems and the working CMTS provides normal service to a cable modem and a protection CMTS, which has its own subnet of IP addresses, takes over service to the cable modem should service from the working CMTS become unavailable, the program instructions comprising instructions for:

(a) participating in registration of the cable modem to allow servicing of the cable modem by the working CMTS; and

(b) obtaining an IP address for the cable modem, which IP address is obtained from an address space outside of the subnet of the working CMTS,

wherein the IP address is used for communications with both the working CMTS and the protection CMTS,

whereby taking over service to the cable modem is performed without re-registering the cable modem or obtaining a new IP address for the cable modem, and comprises requesting that the cable modem adjust at least one of the following parameters;

transmission power, transmission frequency, and transmission time slots.

13. The computer program product of claim 12, further comprising program instructions for communicating the IP address for the cable modem to the protection CMTS.

14. The computer program product of claim 12, further comprising instructions for injecting a host route to the cable modem into a routing protocol.

15. The computer program product of claim 14, wherein the instructions for injecting a host route comprise instructions for providing the host route to one or more aggregation routers servicing the cable network.

16. The computer program product of claim 12, wherein the instructions for participating in registration of the cable modem comprise instructions for participating in a process to assign the IP address for the cable modem.

17. The computer program product of claim 16, wherein the instructions for obtaining the IP address for the cable modem comprise instructions for performing a DHCP relay function.

18. The computer program product of claim 12, further comprising instructions for:

(c) determining that the working CMTS'"'"'s service to the cable modem has or will become unavailable; and

(d) notifying at least one of the cable modem and the protection CMTS that the cable modem should obtain service from the protection CMTS.

19. A CMTS designed or configured to act as a working CMTS for a cable network including the working CMTS which has a subnet of IP addresses for assigning to its cable modems and provides normal service to a cable modem and a protection CMTS which has its own subnet of IP addresses and takes over service to the cable modem should service from the working CMTS become unavailable, the CMTS comprising:

(a) one or more processors;

(b) memory in communication with at least one of the one or more processors; and

(c) wherein at least one of the one or more processors is configured to store registration data for the cable modem in the memory, and wherein the registration data specifies an IP address for the cable modem, which IP address resides in an address space outside the subnet of the working CMTS, and wherein the IP address is used for communication with both the working CMTS and the protection CMTS,

whereby at least one of the one or more processors is configured to allow taking over service from another CMTS without re-registering the cable modem or obtaining a new IP address for the cable modem, and in doing so to request that the cable modem adjust at least one of the following parameters;

transmission power, transmission frequency, and transmission time slots.

20. The CMTS of claim 19, wherein the CMTS is a routing CMTS.

21. The CMTS of claim 19, wherein at least one of the one or more processors is designed or configured to inject a host route to the cable modem into a routing protocol.

22. The CMTS of claim 19, wherein at least one of the one or more processors is configured to notify at least one of the cable modem and the protection CMTS that the cable modem should obtain service from the protection CMTS when the working CMTS'"'"'s service to the cable modem has become unavailable.

23. A method implemented on a protection CMTS for providing redundancy for a cable network having a working CMTS that has a subnet of IP addresses for assigning to its cable modems and provides normal service to a cable modem and the protection CMTS which has its own subnet of IP addresses and takes over service to the cable modem should service from the working CMTS become unavailable, the method comprising:

(a) determining that the working CMTS'"'"'s service to the cable modem has or will become unavailable; and

(b) taking over service to the cable modem while using an IP address for the cable modem that was also used while the working CMTS was servicing the cable modem,

whereby taking over service to the cable modem is performed without re-registering the cable modem or obtaining a new IP address for the cable modem and comprises requesting that the cable modem adjust at least one of the following parameters;

transmission power, transmission frequency, and transmission time slots,

wherein the IP address for the cable modem resides in an address space located outside the subnet for the working CMTS and also outside the subnet for the protection CMTS.

24. The method of claim 23, wherein determining that the working CMTS'"'"'s service to the cable modem has or will become unavailable comprises receiving a notification to that effect from at least one of the cable modem and the working CMTS.

25. The method of claim 23, fully comprising injecting a host route to the cable modem, through the protection CMTS, into a routing protocol.

26. The method of claim 25, wherein injecting a host route comprises providing the host route to one or more aggregation routers servicing the cable network.

27. A method comprising:

using a first address to enable a first device to communicate with a first CMTS which has a subnet of IP addresses for assigning to its cable modems wherein the first address is assigned by the first CMTS and the first address is outside the first CMTS'"'"'s subnet;

attaching to a second CMTS which has its own subnet of IP addresses; and

using said first address to enable said first device to communicate with said second CMTS and thereby allowing the second device to take over service from said first device,

whereby taking over service to the cable modem is performed without re-registering the cable modem or obtaining a new IP address for the cable modem and comprises requesting that the cable modem adjust at least one of the following parameters;

transmission power, transmission frequency, and transmission time slots.

28. The method of claim 27 further including detaching from said first CMTS.

29. The method of claim 27 wherein said first address is an IP address.

30. The method of claim 29 wherein said first device is a cable modem, and wherein said assigning includes assigning said first IP address to said cable modem.

31. The method of claim 27 wherein said first address is associated with said first device, and wherein said method includes injecting a host route for accessing said first device associated with said first address into a router protocol, said host route including routing information which specifies that said first device may be accessed via said first CMTS using said first address.

32. The method of claim 31 further including injecting a second host route for accessing said first device into said router protocol upon determining that said first device has attached to said second CMTS, said second host route including routing information which specifies that said first device may be accessed via said second CMTS using said first address.

33. The method of claim 32 wherein said first device is a cable modem.

34. The method of claim 27 wherein said address assigning includes receiving said first address from DHCP server.

35. The method of claim 34 further including:

submitting an address request for communicating with said second CMTS; and

receiving said first address from said DHCP device for communicating with said second CMTS.

36. The method of claim 27 further including:

detecting a problem in the communication path between said first device and said first CMTS; and

in response to detection of said problem, detaching from said first CMTS and attaching to a second CMTS using said first address.