Optical Access Network Multihoming Resilience
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Solution Overview
Problem
Existing optical access networks lack resilience against failures at the network side termination node, which can disconnect customers from the core network, and require additional signaling links for switchover coordination.
Innovation Solution
Implementing a multihoming approach with two network side termination nodes connected to a single customer side termination node, using a monitoring signal to detect link failures and activate/deactivate transceivers, eliminating the need for additional physical signaling links and ensuring continuous connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protection switching with working and protection fibers is used, then link failure resilience is improved, but device complexity increases due to optical switches and additional fibers
Solution Approach 1:
The invention extracts the optical switch from the network side termination node, removing the complex active component that performed protection switching. Instead, the system uses direct physical redundancy with working and protection fibers connected to separate network side termination nodes, eliminating the need for switching mechanisms while maintaining failure resilience.
Solution Approach 2:
The customer side termination node acts as an intermediary that monitors both working and protection links independently. By having the customer side termination node detect link failures and trigger switchover, the system avoids complex switching devices at the network side while achieving the same protection function.
2Device complexity
If a single network side termination node is used, then device complexity is reduced, but reliability deteriorates because the node itself can fail
Solution Approach 1:
The invention segments the network side termination function across multiple independent nodes. Instead of relying on a single network side termination node, the system uses at least two network side termination nodes, each capable of independently serving the customer side termination node. This segmentation provides redundancy so that if one node fails, the other can take over.
Solution Approach 2:
The system changes the operational state of network side termination nodes from active to standby based on failure detection. The secondary network side termination node remains inactive during normal operation but activates automatically when the primary node fails, changing the system's redundancy parameter from theoretical to actual.
3Reliability
If multihoming with two network side termination nodes is implemented, then reliability is improved, but device complexity increases due to additional transceiver arrangements
Solution Approach 1:
The secondary network side termination node is pre-configured with all necessary transceiver arrangements and connectivity to the customer side termination node, but remains inactive during normal operation. This preliminary preparation allows for instant failover without requiring additional active components, as the standby node is already ready to activate.
Solution Approach 2:
The secondary network side termination node is essentially a copy of the primary node, with identical transceiver arrangements and connectivity capabilities. This copying approach provides redundancy without requiring fundamentally different or more complex equipment, simply duplicating the proven primary node configuration.
4Reliability
If additional physical signaling links are used for switchover coordination, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The existing data communication links between network side termination nodes and customer side termination nodes serve dual purposes: both data transmission and failure detection. The same physical infrastructure used for normal operations is universally utilized for monitoring link status, eliminating the need for separate dedicated signaling links.
Solution Approach 2:
The system implements feedback through the data communication channels themselves, where the absence or presence of data traffic serves as the monitoring signal. When the primary network side termination node stops transmitting, the secondary node detects this feedback and triggers switchover, using the existing communication infrastructure for coordination.
Data Source
AI summary
An optical access network has a first and a second network-side termination node, the first including a first transceiver arrangement connected to a first optical link, configured to send a first signal to a customer side termination node including a transceiver for receiving the first signal, and the second including a second transceiver arrangement connected to a second optical link and configured for sending a second signal to a transceiver of a customer-side termination node via the second link. The transceiver of the customer side termination node has a loopback element emitting a monitoring signal back to the network side termination nodes. Both network-side termination nodes have a link failure detector receiving the monitoring signal.