Algorithm for backup PE selection
First Claim
1. A method for performing fast reroute (FRR) operations at the edge of a computer network, the computer network having an edge device coupled to a neighboring routing domain, the method comprising:
- identifying a set of multiple possible backup edge devices for an address prefix advertised by a device in the neighboring routing domain;
associating one or more metrics with each of the address prefix'"'"'s identified possible backup edge devices;
detecting a loss of communication between the edge device and the neighboring routing domain;
selecting a preferred backup edge device from the address prefix'"'"'s identified set of possible backup edge devices based on the value of at least one of the metrics associated with the possible backup edge devices;
receiving a data packet at the edge device, the received data packet containing a destination address matching the address prefix;
determining whether the received data packet was previously rerouted in accordance with FRR operations; and
rerouting, in response to determining that the received data packet was not previously rerouted, the received data packet to the preferred backup edge device for forwarding to the neighboring routing domain.
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Abstract
A fast reroute (FRR) technique is implemented at the edge of a computer network. If an edge device detects a node or link failure that prevents it from communicating with a neighboring routing domain, the edge device reroutes at least some data packets addressed to that domain to a backup edge device which, in turn, forwards the packets to the neighboring domain. The backup edge device is not permitted to reroute the packets a second time. According to the inventive technique, the edge device first identifies a group one or more possible backup edge devices and then selects at least one preferred backup edge device from the group. The edge device makes its selection based on the values of one or more metrics associated with the possible backup edge devices. The metrics are input to a novel selection algorithm that selects the preferred backup edge device(s) using a hierarchical selection process or a weighted-metric selection process, or some combination thereof.
65 Citations
33 Claims
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1. A method for performing fast reroute (FRR) operations at the edge of a computer network, the computer network having an edge device coupled to a neighboring routing domain, the method comprising:
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identifying a set of multiple possible backup edge devices for an address prefix advertised by a device in the neighboring routing domain; associating one or more metrics with each of the address prefix'"'"'s identified possible backup edge devices; detecting a loss of communication between the edge device and the neighboring routing domain; selecting a preferred backup edge device from the address prefix'"'"'s identified set of possible backup edge devices based on the value of at least one of the metrics associated with the possible backup edge devices; receiving a data packet at the edge device, the received data packet containing a destination address matching the address prefix; determining whether the received data packet was previously rerouted in accordance with FRR operations; and rerouting, in response to determining that the received data packet was not previously rerouted, the received data packet to the preferred backup edge device for forwarding to the neighboring routing domain. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 15, 16, 17)
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11. A method for performing fast reroute (FRR) operations at the edge of a computer network, the computer network having an edge device coupled to a neighboring routing domain, the method comprising:
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identifying a set of multiple possible backup edge devices for an address prefix; determining whether the address prefix is reachable to the edge device via an interior route; in response to determining that the address prefix is not reachable, determining that none of the address prefix'"'"'s identified possible backup edge devices are to be used as a preferred backup edge device; and in response to determining that the address prefix is reachable, removing from the address prefix'"'"'s identified set of possible backup edge devices any possible backup edge device that is not capable of functioning as a backup edge device, and associating one or more metrics with each of the address prefix'"'"'s identified possible backup edge devices, detecting a loss of communication between the edge device and the neighboring routing domain, selecting the preferred backup edge device from the address prefix'"'"'s identified set of possible backup edge devices based on the value of at least one of the metrics associated with the possible backup edge devices, receiving a data packet at the edge device, the received data packet containing a destination address matching the address prefix, and rerouting, in response to determining that the received data packet was not previously rerouted, the received data packet to the preferred backup edge device for forwarding to the neighboring routing domain. - View Dependent Claims (12)
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18. A network node configured to perform fast reroute (FRR) operations at the edge of a computer network, the network node comprising:
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a processor; a first network interface adapted to receive an address prefix advertised by a device in a neighboring routing domain; a second network interface adapted to receive a data packet containing a destination address matching the address prefix; and a memory adapted to store instructions which are executable by the processor for performing the steps; identifying a set of multiple possible backup edge devices for the address prefix; associating one or more metrics with each of the address prefix'"'"'s identified possible backup edge devices; detecting a loss of communication over the first network interface; selecting a preferred backup edge device from the address prefix'"'"'s identified set of possible backup edge devices based on the value of at least one of the metrics associated with the possible backup edge devices; determining whether the data packet received at the second network interface was previously rerouted in accordance with FRR operations; and rerouting, in response to determining that the received data packet was not previously rerouted, the received data packet to the preferred backup edge device for forwarding to the neighboring routing domain. - View Dependent Claims (19, 20, 21, 22)
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23. A network node configured to perform fast reroute (FRR) operations at the edge of a computer network, the network node comprising:
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a processor; a first network interface configured to receive an address prefix advertised by a device in a neighboring routing domain; a second network interface configured to receive a data packet containing a destination address matching the address prefix; and a memory configured to store instructions which are executable by the processor for performing the steps; identifying a set of multiple possible backup edge devices for the address prefix; determining whether the address prefix is reachable to the network node via an interior route; in response to determining that the address prefix is not reachable, determining that none of the address prefix'"'"'s identified possible backup edge devices are to be used as a preferred backup edge device; and in response to determining that the address prefix is reachable, removing from the address prefix'"'"'s identified set of possible backup edge devices any possible backup edge device that is not capable of functioning as a backup edge device, and associating one or more metrics with each of the address prefix'"'"'s identified possible backup edge devices, detecting a loss of communication over the first network interface, selecting the preferred backup edge device from the address prefix'"'"'s identified set of possible backup edge devices based on the value of at least one of the metrics associated with the possible backup edge devices, and rerouting, in response to determining that the received data packet was not previously rerouted, the received data packet to the preferred backup edge device for forwarding to the neighboring routing domain.
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24. A network node configured to perform fast reroute (FRR) operations at the edge of a computer network, the network node being coupled to a neighboring routing domain, the network node comprising:
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means for identifying a set of multiple possible backup edge devices for an address prefix advertised by a device in the neighboring routing domain; means for associating one or more metrics with each of the address prefix'"'"'s identified possible backup edge devices; means for detecting a loss of communication with the neighboring routing domain; means for selecting a preferred backup edge device from the address prefix'"'"'s identified set of possible backup edge devices based on the value of at least one of the metrics associated with the possible backup edge devices; means for receiving a data packet containing a destination address matching the address prefix; means for determining whether the received data packet was previously rerouted in accordance with FRR operations; and means for rerouting, in response to determining that the received data packet was not previously rerouted, the received data packet to the preferred backup edge device for forwarding to the neighboring routing domain. - View Dependent Claims (25, 26, 27, 28)
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29. A network node configured to perform fast reroute (FRR) operations at the edge of a computer network, the network node being coupled to a neighboring routing domain, the network node comprising:
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means for identifying a set of multiple possible backup edge devices for an address prefix advertised by a device in the neighboring routing domain; means for determining whether the address prefix is reachable to the network node via an interior route; means for determining, in response to determining that the address prefix is not reachable, that none of the address prefix'"'"'s identified possible backup edge devices are to be used as a preferred backup edge device; means for removing, in response to determining that the address prefix is reachable, from the address prefix'"'"'s identified set of possible backup edge devices any possible backup edge device that is not capable of functioning as a backup edge device; means for associating one or more metrics with each of the address prefix'"'"'s identified possible backup edge devices; means for detecting a loss of communication with the neighboring routing domain; means for selecting the preferred backup edge device from the address prefix'"'"'s identified set of possible backup edge devices based on the value of at least one of the metrics associated with the possible backup edge devices; means for receiving a data packet containing a destination address matching the address prefix; and means for rerouting, in response to determining that the received data packet was not previously rerouted, the received data packet to the preferred backup edge device for forwarding to the neighboring routing domain.
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30. A computer network, comprising:
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a first edge device coupled to a neighboring routing domain; and a second edge device coupled to the neighboring routing domain, the second edge device being configured to; identify a set of multiple possible backup edge devices for an address prefix advertised by a device in the neighboring routing domain, the first edge device being identified as one of the possible backup edge devices for the address prefix; associate one or more metrics with each of the address prefix'"'"'s identified possible backup edge devices; detect a loss of communication with the neighboring routing domain; select the first edge device as a preferred backup edge device from among the address prefix'"'"'s identified set of possible backup edge devices based on the value of at least one of the metrics associated with the possible backup edge devices; receive a data packet containing a destination address matching the address prefix; determine whether the received data packet was previously rerouted in accordance with FRR operations; and reroute, in response to determining that the received data packet was not previously rerouted, the received data packet to the first edge device for forwarding to the neighboring routing domain. - View Dependent Claims (31, 32)
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33. A computer-readable medium storing instructions for execution on a processor for the practice of a method of performing fast reroute (FRR) operations at the edge of a computer network, the network having an edge device coupled to a neighboring routing domain, the method comprising:
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identifying a set of multiple possible backup edge devices for an address prefix advertised by a device in the neighboring routing domain; associating one or more metrics with each of the address prefix'"'"'s identified possible backup edge devices; detecting a loss of communication between the edge device and the neighboring routing domain; selecting a preferred backup edge device from the address prefix'"'"'s identified set of possible backup edge devices based on the value of at least one of the metrics associated with the possible backup edge devices; receiving a data packet at the edge device, the received data packet containing a destination address matching the address prefix; determining whether the received data packet was previously rerouted in accordance with FRR operations; and rerouting, in response to determining that the received data packet was not previously rerouted, the received data packet to the preferred backup edge device for forwarding to the neighboring routing domain.
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Specification