Avoiding micro-loops in a ring topology of a network
First Claim
1. A method, comprising:
- performing operations in a network including bi-directional communicating packets according to a ring topology by a plurality of packet switching devices, with the plurality of packet switching devices including a particular packet switching device, a first neighbor packet switching device, and a non-neighbor packet switching device, with the particular packet switching device and the first neighbor packet switching device being neighbors in the ring topology via particular communications when active, and with said operations including;
generating, by the particular packet switching device, a particular packet including particular link state information identifying an unavailability of said particular communications; and
sending through the ring topology, by the particular packet switching device to the non-neighbor packet switching device the particular packet causing link state information advertising a high cost of said particular communication to initially propagate neighbor-by-neighbor through the ring topology not from the particular packet switching device but rather neighbor-by-neighbor through the ring topology from the non-neighbor packet switching device including away from the non-neighbor packet switching device towards the particular packet switching device;
wherein the particular packet switching device selectively sends said particular link state information identifying the unavailability of said particular communications to only a single packet switching device of the plurality of packet switching devices in the ring topology that is not a current neighbor of the particular packet switching device, with the single non-neighbor packet switching device being the non-neighbor packet switching device that is a packet switching device furthest away from the particular packet switching device in the ring topology in the direction not through said particular communications with forwarding information to send packets addressed to the first neighbor packet switching device through the particular packet switching device.
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Abstract
In one embodiment, micro-loops are avoided in ring topologies of packet switching devices by changing the order of propagation of link state information concerning failed communications between a particular packet switching device and a neighbor packet switching device. In one embodiment, the particular packet switching device communicates link state information of a high cost of the particular communications (e.g., in the direction from particular to neighbor packet switching devices) such that this link state information will propagate towards the particular packet switching device from at least from the furthest packet switching device in the ring topology that is currently configured to forward packets having a destination address of the neighbor packet switching device through the particular packet switching device.
70 Citations
16 Claims
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1. A method, comprising:
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performing operations in a network including bi-directional communicating packets according to a ring topology by a plurality of packet switching devices, with the plurality of packet switching devices including a particular packet switching device, a first neighbor packet switching device, and a non-neighbor packet switching device, with the particular packet switching device and the first neighbor packet switching device being neighbors in the ring topology via particular communications when active, and with said operations including; generating, by the particular packet switching device, a particular packet including particular link state information identifying an unavailability of said particular communications; and sending through the ring topology, by the particular packet switching device to the non-neighbor packet switching device the particular packet causing link state information advertising a high cost of said particular communication to initially propagate neighbor-by-neighbor through the ring topology not from the particular packet switching device but rather neighbor-by-neighbor through the ring topology from the non-neighbor packet switching device including away from the non-neighbor packet switching device towards the particular packet switching device; wherein the particular packet switching device selectively sends said particular link state information identifying the unavailability of said particular communications to only a single packet switching device of the plurality of packet switching devices in the ring topology that is not a current neighbor of the particular packet switching device, with the single non-neighbor packet switching device being the non-neighbor packet switching device that is a packet switching device furthest away from the particular packet switching device in the ring topology in the direction not through said particular communications with forwarding information to send packets addressed to the first neighbor packet switching device through the particular packet switching device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A particular packet switching device, comprising:
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one or more processing elements; memory; a plurality of interfaces sending and receiving packets; and one or more packet switching mechanisms packet switching packets among said interfaces; wherein the particular packet switching device performs operations, with said operations including; generating a particular packet including tunnel information, and with the particular packet including particular link state information identifying an unavailability of particular communications in a network of a plurality of packet switching devices communicating bi-directionally in and according to a ring topology, with the particular packet switching device and a first neighbor packet switching device being neighbors in the ring topology via said particular communications when active and not neighbors in the ring topology when said particular communications is unavailable; and sending, via a tunnel not passing through said particular communications based on said tunnel information through the ring topology to a non-neighbor packet switching device in the ring topology when said particular communications is unavailable, the particular packet causing link state information advertising a high cost of said particular communication to initially propagate neighbor-by-neighbor through the ring topology not from the particular packet switching device but rather neighbor-by-neighbor through the ring topology away from the non-neighbor packet switching device including in neighbor-exchanged link state information away from the non-neighbor packet switching device towards the particular packet switching device in the direction that is not through said particular communications. - View Dependent Claims (11, 12, 13)
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14. A method, comprising:
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generating, by a particular packet switching device, a particular packet including tunnel information, and with the particular packet including particular link state information identifying a high cost of particular communications between a first neighbor packet switching device and the particular packet switching device in a ring topology, wherein the particular packet switching device and the first neighbor packet switching device are two of a plurality of packet switching devices in a network communicating bi-directionally according to the ring topology, with the particular packet switching device and the first neighbor packet switching device being neighbors in the ring topology via said particular communications when active; and
wherein each of the plurality of packet switching devices exchanges link state information with their current neighbors in the ring topology and updates their respective local forwarding information accordingly; andsending, by the particular packet switching device via a tunnel not passing through said particular communications based on said tunnel information through the ring topology to an intermediate packet switching device of the plurality of packet switching devices in the ring topology and which is not a neighbor of the particular packet switching device in the ring topology when said particular communications is unavailable, the particular packet causing link state information advertising a high cost of said particular communication to initially propagate neighbor-by-neighbor through the ring topology not from the particular packet switching device but rather neighbor-by-neighbor through the ring topology from the intermediate packet switching device including in neighbor-exchanged link state information away from the intermediate packet switching device towards the particular packet switching device in the direction that is not through said particular communications. - View Dependent Claims (15, 16)
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Specification