Dormant backup link for OSPF network protection
First Claim
1. A method of protecting an Open Shortest Path First (OSPF) network against network failures affecting traffic flow between an interior router (IR) and a predetermined primary area border router (ABR) using a back-up link between the IR and a predetermined alternate ABR, the method comprising steps of:
- maintaining the back-up link in a dormant state during normal operations of the network, such that no traffic is forwarded to the back-up link during normal operations of the network; and
activating the back-up link in response to a network failure affecting communications between the IR and the primary ABR, such that traffic can be routed between the IR and the alternate ABR through the back-up link comprising;
detecting the network failure affecting communications between the IR and the primary ABS comprising;
detecting a loss of communications between the IR and the primary ABR;
monitoring a link between the IR and the primary ABR for a predetermined period, to detect recovery of communications;
declaring a link failure if recovery of communications between the IR and the primary ABR is not detected within the predetermined period;
promoting the back-up link to a valid status; and
advertising the back-up as a valid route.
11 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus provides protection against resource failures in Open Shortest Path First (OSPF) networks, without increasing the complexity of the network topology and/or management. An internal router (IR) automatically maintains a back-up link in a dormant state until a network failure affecting communications with a primary adjacent area border router (ABR) is detected. Upon detection of the network failure, the IR activates the back-up link in order to enable traffic flow to an alternate adjacent ABR, which by-passes the network failure. Upon recovery of communications with the primary adjacent ABR, the IR automatically deactivates the back-up link and resumes traffic flow through the primary adjacent ABR. As a result, traffic is forwarded into the back-up link only when communications with the primary adjacent ABR has failed, thereby maintaining simplicity in the network topology, and minimizing network management and administration requirements.
43 Citations
20 Claims
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1. A method of protecting an Open Shortest Path First (OSPF) network against network failures affecting traffic flow between an interior router (IR) and a predetermined primary area border router (ABR) using a back-up link between the IR and a predetermined alternate ABR, the method comprising steps of:
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maintaining the back-up link in a dormant state during normal operations of the network, such that no traffic is forwarded to the back-up link during normal operations of the network; and activating the back-up link in response to a network failure affecting communications between the IR and the primary ABR, such that traffic can be routed between the IR and the alternate ABR through the back-up link comprising; detecting the network failure affecting communications between the IR and the primary ABS comprising; detecting a loss of communications between the IR and the primary ABR; monitoring a link between the IR and the primary ABR for a predetermined period, to detect recovery of communications; declaring a link failure if recovery of communications between the IR and the primary ABR is not detected within the predetermined period; promoting the back-up link to a valid status; and
advertising the back-up as a valid route. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A router adapted for protecting an Open Shortest Path First (OSPF) network against network failures affecting communication with a predetermined adjacent router using a back-up link predetermined alternate router, the router comprising:
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means for maintaining the back-up link to a dormant state during normal operations of the network, such that no traffic is forwarded to the back-up link during normal operations of the network; and means for activating the back-up link in response to a network failure affecting communications with primary router, such that traffic can be routed through the back-up link comprising; means for detecting the network failure affecting communications with the primary adjacent router comprising; means for detecting a loss of communications with the primary adjacent router; means for monitoring a link to the primary adjacent router for a predetermined period, to detect recovery of communications; means for declaring a link failure if recovery of communications with the primary adjacent is not detected within the predetermined period; means for promoting the back-up link to a valid status; and means for advertising the back-up as a valid route. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A computer-readable storage medium encoded with a software program adapted to control a router of an Open Shortest Path First (OSPF) network to protect against network failures affecting communications with a predetermined primary adjacent router using a back-up link to a predetermined alternate router, the computer-readable medium comprising:
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software adapted to control the router to maintain the back-up link in a dormant state during normal operations of the network, such that no traffic is forwarded to the back-up link during normal operations of the network; and software adapted to control the router to activate the back-up link in response to a network failure affecting communication with the primary router, such that traffic can be routed through the back-up link comprising; software adapted to control the router to detect the network failure affecting communications with the primary adjacent router comprising; software adapted to control the router to detect a loss of communications with the primary adjacent router; software adapted to control the router to monitor a link to the primary adjacent router for a predetermined period, to detect recovery of communications; software adapted to control the router to declare a link failure if recovery of communications with the primary adjacent router is not detected within the predetermined period; software adapted to control the router to promote the back-up link to an active status; and software adapted to control the router to advertise the back-up link as a valid route. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification