Switching to a protection path without causing packet reordering

摘要

In one embodiment, a working path through a packet switched network is protected by a protection path. In response to a switchover condition, a packet switching device ceases to enqueue packets for sending over the current working path. Packets are enqueue for sending over the protection path, with a delay by a predetermined duration before beginning to dequeue and send of packets over the protection path. A sending packet switching device, by delaying an appropriate predetermined duration, can guarantee that the protection switching operation will not induce packet reordering nor packet loss. This predetermined delay is calculated, possibly based on measurements, of different component delays of sending packets over the working and protection paths. For example, these component delays typically include latency within the sending device, latency of communications between the sending device and the destination, and latency with the destination.

主权项

1. A method, comprising:
sending a plurality of packets from a packet switching device onto a first path to a destination, wherein the first path is network protected by a second path; calculating a predetermine time duration that includes one or more latencies within the packet switching device, one or more latencies between the packet switching device and the destination, and one or more latencies within the destination; in response to an identified protection switching condition, switching from said sending packets over the first path to sending packets from the packet switching device over the second path to the destination after delaying at least the predetermined time duration after the identified protection switching condition, wherein said predetermined time duration is calculated to be at least long enough to guarantee that said packets sent over the second path arrive at a common point within the destination after the last of said packets said sent over the first path.