Optical Line Terminal Seamless Switchover via Service Synchronization
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Solution Overview
Problem
In protected Passive Optical Networks (PONs), seamless switchover during failures of the active optical link is hindered by the time-consuming process of acquiring information about network services, leading to potential service interruptions, as the failover Optical Line Terminal (OLT) needs to be aware of the services provided by the active OLT and the network topology changes over time.
Innovation Solution
The proposed solution involves the active OLT synchronizing service instance information with the failover OLT and the Aggregation (AGG) network during normal operation, allowing the failover OLT to quickly resume services by retrieving stored information and sending control messages to the AGG network to direct traffic to the failover link, using standard protocols like ERPS or MPLS, thereby minimizing service interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the failover OLT acquires service instance information from the active OLT upon failure, then the switchover can be performed, but the service interruption time increases due to the time-consuming information acquisition process
Solution Approach 1:
The active OLT proactively sends service instance information to the failover OLT before any failure occurs. This preliminary action ensures that the failover OLT already has the necessary information in its memory when a failure happens, eliminating the need for time-consuming information acquisition during the switchover process and thus reducing service interruption time while maintaining reliable service protection
2Speed
If the active OLT synchronizes service instance information to the failover OLT during normal operation, then the failover OLT is prepared for quick switchover, but the system complexity increases due to the additional synchronization mechanism
Solution Approach 1:
The patent uses an intermediary communication mechanism between the active OLT and failover OLT to synchronize service instance information. This intermediary approach allows structured data exchange through defined protocols, enabling automated synchronization without requiring complex manual configuration or management interfaces, thus achieving fast switchover while keeping the system manageable
3Productivity
If the failover OLT retrieves service instance information after failure, then service can be resumed, but the automation level decreases due to the need for post-failure information acquisition
Solution Approach 1:
The active OLT performs preliminary action by automatically sending service instance information to the failover OLT before failure occurs. This ensures the failover OLT has all necessary information pre-loaded in its memory, enabling fully automated service resumption upon failure without requiring any post-failure information acquisition processes, thus maintaining high automation level while improving service resumption efficiency
Data Source
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Figure 5A~5B
AI summary
The present disclosure relates to an optical line terminal, OLT, for a protected passive optical network, PON, connected to an AGG network. A protected PON comprises two OLTs, one an active OLT 110 arranged to connect to one or more optical network terminals, ONTs, 301-303, thereby forming an active link 101, and, a failover OLT 120 arranged to connect to the one or more ONTs 301-303, thereby forming a failover link 102. The OLTs 110 and 120 may be co-located or located in geographically remote locations, and, are respectively connected to the AGG network which allows traffic to and from the ONTs to be routed to a core network. In case of a failure on the active link 101, a seamless switchover ensuring minimal service interruption time should be performed by directing the traffic to and from the ONTs 301-310 from the active link 101 to the failover link 102.