Overview
This topic explains the band failure recovery mechanism used in optical networks. It details how the system compensates for power transfer between C-band and L-band signals and ensures stable operation and recovery during a band failure.
A band failure recovery is a mechanism that
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applies dual-band PSD profiles to both C-band and L-band devices to compensate for power transfer caused by Stimulated Raman Scattering (SRS),
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coordinates with agent nodes along the transmission path, and
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manages PSD profile switching and recovery of each node in case of band failure.
Band Failure Recovery in C-band and L-band optical networks
NCS 1010 can be configured to operate in both C-band and L-band wavelengths to increase the capacity of optical fibers. This is achieved by connecting the C-band OLT or ILA line cards to the corresponding L-band OLT or ILA line cards. When C-band and L-band signals travel through the same fiber, SRS causes a transfer of optical power from higher to lower frequencies. This process alters the C-band power profile . BFR compensates for this by applying dual-band PSD profiles to both C-band and L-band devices.
The source OLT node functions as the BFR manager for all nodes in the transmit direction. Other nodes in the path act as BFR agent nodes and report to the manager. The manager node collects information from agent nodes, coordinates failure, and recovery actions.
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When a band fails in a C and L band network, the surviving band experiences a change in optical power due to the absence of SRS.
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The BFR manager sends commands to the agent nodes to switch the PSD profile on the surviving band to a single-band PSD profile.
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After resolving the failure, the BFR manager initiates recovery on each failed band node to ensure there is no traffic impact on the surviving band.