9-57
Cisco ONS 15454 DWDM Reference Manual, R8.5
78-18343-02
Chapter 9 Node Reference
9.6 Automatic Node Setup
9.6 Automatic Node Setup
Automatic node setup (ANS) is a TCC2/TCC2P function that adjusts values of the variable optical
attenuators (VOAs) on the DWDM channel paths to equalize the per-channel power at the amplifier
input. This power equalization means that at launch, all channels have the same amplifier power,
independent from the input signal on the client interface and independent from the path crossed by the
signal inside the node. This equalization is needed for two reasons:
• Every path introduces a different penalty on the signal that crosses it.
• Client interfaces add their signal to the ONS 15454 DWDM ring with different power levels.
To support ANS, integrated VOAs and photodiodes are provided in the following cards:
• AD-xB-xx.x card express and drop paths
• AD-xC-xx.x card express and add paths
• 4MD-xx.x card add paths
• 32MUX-O card add paths
• 32WSS/40-WSS-C/40-WSS-CE/40-WXC-C add and pass through paths
• 32DMX-O card drop paths
• 32DMX, 40-DMX-C, 40-DMX-CE card input port
• 40-MUX-C card output port
Optical power is equalized by regulating the VOAs. Based on the expected per-channel power, ANS
automatically calculates the VOA values by:
• Reconstructing the different channels paths.
• Retrieving the path insertion loss (stored in each DWDM transmission element).
VOAs operate in one of three working modes:
• Automatic VOA Shutdown—In this mode, the VOA is set at maximum attenuation value. Automatic
VOA shutdown mode is set when the channel is not provisioned to ensure system reliability in the
event that power is accidentally inserted.
• Constant Attenuation Value—In this mode, the VOA is regulated to a constant attenuation
independent from the value of the input signal. Constant attenuation value mode is set on VOAs
associated to aggregated paths.
• Constant Power Value—In this mode, the VOA values are automatically regulated to keep a constant
output power when changes occur to the input power signal. This working condition is set on VOAs
associated to a single channel path.
ANS calculates the following VOA provisioning parameters:
4 Side A 32WSS COM TX to Side A OPT-BST
COM RX
11 Side B 32WSS COM TX to Side B OPT-BST
COM RX
5 Side A 32WSS COM RX to Side A OPT-PRE
COM TX
12 Side B OPT-BST COM TX to Side B OPT-PRE
COM RX
6 Side A 32DMX COM RX to Side A 32WSS DROP TX 13 Side B DCU RX to Side B OPT-PRE DC TX
1
7 Side A 32WSS EXP TX to Side B 32WSS EXP RX 14 Side B DCU TX to Side B OPT-PRE DC RX
1
1. If a DCU is not installed, a 4-dB attenuator loop, +/–1 dB must be installed between the OPT-PRE DC ports.
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