Optical Terminal Automatic Protection Switching
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Solution Overview
Problem
Existing automatic protection switching in optical networks fails to efficiently update traffic flow, leading to slow switch-over times and potential traffic interruption or packet loss, especially in scenarios with uni-directional traffic where client devices do not promptly send messages to update Ethernet network MAC address entries.
Innovation Solution
An optical terminal equipped with a controller that detects primary path failures, initiates automatic protection switches to secondary paths, and generates traffic flow update messages, such as Gratuitous ARP or NDP messages, containing client device MAC addresses to update Ethernet network switches without relying on client device activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If automatic protection switching is implemented without traffic flow update mechanisms, then the protection switching can be performed, but the switch-over time increases and traffic interruption occurs
Solution Approach 1:
The patent applies preliminary action by having the protecting OLT prepare and send traffic flow update messages (Gratuitous ARP/NDP) proactively after detecting a failure, before the affected ONTs can send their own update messages. This preliminary update action ensures that Ethernet network switches receive the necessary MAC address information quickly, reducing switch-over time and preventing traffic interruption.
2Device complexity
If client devices are relied upon to send update messages during protection switching, then protocol simplicity is maintained, but traffic flow updates are delayed or lost in uni-directional traffic scenarios
Solution Approach 1:
The patent introduces an intermediary mechanism where the protecting OLT acts as a mediator to send traffic flow update messages on behalf of the affected ONTs. This intermediary approach ensures that Ethernet network switches receive accurate MAC address information even when client devices cannot promptly send updates due to uni-directional traffic conditions or protocol limitations.
3Productivity
If protection switching is performed without updating Ethernet network MAC address entries, then the switching operation is simple, but packet loss occurs due to incorrect MAC address forwarding
Solution Approach 1:
The patent implements feedback by having the protecting OLT send traffic flow update messages containing MAC address information back to Ethernet network switches after performing protection switching. This feedback mechanism ensures that the switches update their MAC address tables with correct information from the new path, preventing packet loss while maintaining fast switching operations.
Data Source
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AI summary
There is described an optical terminal (500) for use in a passive optical network. The optical terminal comprises an optical I/O module (501) for sending and receiving optical data packets along an optical fibre, an electrical I/O module (502) for sending and receiving electrical data packets via an electrical connection, a signal converter (503) operatively connected to the optical and electrical I/O modules for converting the data packets between optical and electrical formats, and a controller (504) for controlling the operation of the I/O modules and the signal converter. The controller is configured to detect a failure of a primary data path (201) in the optical network, initiate an automatic protection switch to a secondary data path (401) for optical data packets, and generate traffic flow update messages to be sent upstream. Each traffic flow update message contains, as a source address, a MAC address of a client device downstream of the terminal.