Method of using routing protocols to reroute packets during a link failure
First Claim
1. An improved first router that routes packets according to their logical network addresses, the first router being connected between a first link, a second bidirectional link, and a third link and ordinarily receiving packets addressed to a host on the third link via the first link, the improvement comprising:
- a first link failure detector for detecting a failure in the first link; and
a routing protocol message provider which responds to a detected failure by sending a sequence of routing protocol messages on the second bidirectional link, the sequence being responded to by a second router that is accessible via the second bidirectional link and that ordinarily routes packets addressed to the host via the first link, the second router responding to the sequence by routing those packets via the second bidirectional link.
2 Assignments
0 Petitions
Accused Products
Abstract
The preferred embodiment of the present invention is a cable modem apparatus for reliably providing a personal computer access to the Internet through a cable television link and a public switched telephone network link. The invention includes: a cable television link failure detector connected to the cable television link; a message generator connected to the cable television link failure detector, where the message generator is configured to generate at least one message responsive to the cable television link failure detector; and a message transmitter connected to the message generator, where the message transmitter is configured to transmit the at least one message through the public switched telephone network link to cause Internet communications to be communicated to the personal computer through the public switch telephone network link.
-
Citations
42 Claims
-
1. An improved first router that routes packets according to their logical network addresses, the first router being connected between a first link, a second bidirectional link, and a third link and ordinarily receiving packets addressed to a host on the third link via the first link, the improvement comprising:
-
a first link failure detector for detecting a failure in the first link; and
a routing protocol message provider which responds to a detected failure by sending a sequence of routing protocol messages on the second bidirectional link, the sequence being responded to by a second router that is accessible via the second bidirectional link and that ordinarily routes packets addressed to the host via the first link, the second router responding to the sequence by routing those packets via the second bidirectional link. - View Dependent Claims (2)
-
-
3. A method for routing data communicated to a first router from a second router, wherein the first router and the second router are connected by a first link and a second link, said method comprising steps of:
-
routing data through the first link from the second router to the first router during an absence of a failure of the first link;
routing data through the second link from the first router to the second router during the absence of the failure;
detecting, at the first router, the failure of the first link from the second router to the first router;
generating at least one message at the first router responsive to detecting the failure of the first link;
transmitting the at least one message from the first router to the second router through the second link; and
routing data through the second link from the second router to the first router during the failure responsive to receiving the at least one message from the first router along the second link. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
detecting, at the first router, that the failure of the first link has ended, generating a failure ended message at the first router responsive to detecting the failure of the first link has ended; transmitting the failure ended message from the first router to the second router through the second bidirectional link; and
resuming routing of data through the first link from the second router to the first router.
-
-
9. The method of claim 3, wherein the data includes IP packets including IP addresses, and wherein the first router is connected to at least one personal computer, and wherein the second router is connected to the Internet.
-
10. The method of claim 9, wherein the first router is connected through a local area network to a plurality of personal computers.
-
11. The method of claim 3, wherein the first link is a one-way link from the second router to the first router.
-
12. The method of claim 3, wherein the first link is a cable television RF link, and wherein the second bidirectional link is a conventional two-way telephone line.
-
13. The method of claim 3, further including maintaining a routing table for the second router, wherein the routing table is altered responsive to receiving at least one failure messages from the first router.
-
14. A cable modem apparatus for reliably providing a personal computer access to the Internet through a cable television link and a public switched telephone network link, said apparatus comprising:
-
a cable television link failure detector connected to the cable television link;
a message generator connected to said cable television link failure detector, wherein said message generator is configured to generate at least one message responsive to said cable television link failure detector detecting cable television link failures; and
a message transmitter connected to said message generator, wherein said message transmitter is configured to transmit the at least one message through the public switched telephone network link to cause Internet communications to be communicated to the personal computer through the public switch telephone network link by changing IP datagram routing. - View Dependent Claims (15, 16)
-
-
17. A method for routing data communicated to a first router from a second router, wherein the first router and the second router are connected by a first communication path and a second communication path, said method comprising steps of:
-
routing data from the second router to the first router through the first communication path during an absence of a failure of the first communication path;
routing data from the first router to the second router through the second communications path during the absence of the failure;
receiving at the second router at least one message through the second communication path;
determining from the at least one message that the failure of the first communication path has occurred;
changing at least one routing table responsive to receiving the at least one message through the second communication path; and
routing data from the second router to the first router through the second communication path during the failure, responsive to changing at least one table. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
the data includes IP packets including IP addresses;
the first router being connected to at least one personal computer; and
the second router being connected to the Internet.
-
-
28. The method of claim 17, wherein:
-
the first communication path is a cable television RF communication path; and
the second communication path is a telephone line.
-
-
29. The method of claim 17, further including the step of maintaining a routing table for the second router, wherein responsive to determining a change of status of the first communication path the table is changed.
-
30. A method for communicating data to an RF modem from a CATV head end, wherein the RF modem and the CATV head end are connected by an first communication path and a second communication path, the method comprising the steps performed in the RF modem of:
-
receiving data communicated from the CATV head end to the RF modem over the first communication path during an absence of a failure of the first communication path;
transmitting data communicated from the RF modem to the CATV head over the second communication path during the absence of the failure;
determining that the failure of the first communication path has occurred;
notifying the CATV head end to communicate data from the CATV head end to the RF modem over the second communication path; and
receiving data communicated from the CATV head end to the RF modem over the second communication path during the failure responsive to the CATV head end changing IP datagram routing. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
generating at least one routing message; and
communicating at least one routing message to the CATV head end over the second communication path.
-
-
32. The method of claim 31, wherein the first communication path is an RF communication link.
-
33. The method of claim 32, wherein the second communication path is bidirectional.
-
34. The method of claim 33, wherein the second communication path is a public switched telephone network link.
-
35. The method of claim 34, wherein the RF communication link is unidirectional.
-
36. The method of claim 35, wherein the at least one routing message is a routing information protocol (RIP) message.
-
37. The method of claim 31, further comprising the steps performed in the RF modem of:
-
determining that the first communication path has become operational;
notifying the CATV head end to communicate data from the CATV head end to the RF modem over the first communication path; and
receiving data communicated from the CATV head end to the RF modem over the first communication path.
-
-
38. The method of claim 37, wherein the first communication path carries a majority of the data from the CATV head end to the RF modem while the first communication path is operational, and wherein the second communication path carries a majority of the data from the CATV head end to the RF modem while the first communication path has failed.
-
39. The method of claim 38, wherein the first communication path operates at a faster bit rate than the second communication path.
-
40. The method of claim 39, wherein the second communication path carries data from the RF modem to the CATV head end independent of the first communication path failing.
-
41. The method of claim 40, wherein the first communication path is a unidirectional RF communication link and the second communication path is a bidirectional public switched telephone network link.
-
42. The method of claim 41, wherein the at least one routing message is a routing inflation protocol (RIP) message.
Specification