Raman Tuning
This chapter describes the Raman Tuning optical application for Cisco NCS 1010.
• Overview of Raman Tuning, on page 1
• Raman Tuning with OTDR Lock, on page 8
Overview of Raman Tuning
Raman Tuning Algorithm calculates and sets the different pump power values across five Raman pumps to
obtain the target Raman Gain on a span. Raman tuning runs in both directions of the span independently at
the node level. Raman tuning requires communication between peer nodes. Hence, OSC communication
between the two nodes is a prerequisite for Raman Tuning.
Raman tuning algorithm uses the following parameters to calculate the pump powers necessary to achieve
the target Raman gain.
• Fiber type
• Fiber length
• Loss on the fiber at each pump wavelength
• Loss on the fiber at the signal wavelength
If you configure a span length value, Raman tuning uses this value.
Raman tuning is disabled by default. Raman tuning is enabled if automatic link bring up is enabled. You can
manually trigger Raman tuning if necessary. The NCS 1010 initiates the tuning process under the following
circumstances:
• During the initial link bring up
• After a fiber cut
• After a power cycle event
• After a line card cold reload event
• After a DFB shut or unshut event
• After an OTS controller shut or unshut event on near end or far end node
• After modification of span length configuration
Raman Tuning
1
Raman Tuning
Overview of Raman Tuning
Raman tuning is traffic impacting. When Raman tuning is in progress, the amplifier on the far end of the span
is turned off to block traffic. The Optical Safety Remote Interlock (OSRI) feature allows turning off the
amplifier on the peer node for Raman tuning. Only the OSC is active on the link while Raman tuning is in
progress.
At the LINE-TX port on the far end of the span, the dedicated Raman probe (DFB) is combined with the
transmitted optical channels. The DFB laser at 191.1 THz is used to perform a link continuity check on the
Raman span for optical safety. The DFB laser is used during Raman tuning.
At the LINE-RX port, five wavelengths between 1424 nm and 1495 nm are inserted in the counter propagating
direction of the signal to provide amplification using the Raman effect for both C and L band optical channels.
The system triggers Raman tuning when a link goes down and comes back up. After completing Raman tuning
successfully, soft reloads, RP reloads, Raman OSRI change, and Raman Force APR change do not retrigger
Raman tuning.
The following table lists and describes the different Raman Tuning Status.
Raman Tuning Status Description
WORKING – MEASUREMENT The algorithm is measuring the span loss on the link.
WORKING – CALCULATION The algorithm is calculating the gain target and
required pump powers.
WORKING – OPTIMIZATION The algorithm is optimizing the pump powers.
TUNED Raman tuning is complete.
BLOCKED The system is unable to perform Raman tuning. This
status can occur because the link is down or the system
detected high Raman Back Reflection.
DISABLED Raman tuning is disabled.
Raman tuning works in the following three modes:
• Auto mode: Raman tuning defines the target gain and sets the pump powers and DFB VOA attenuation
to achieve the target gain overwriting user configuration.
• Gain mode: User defines the gain target and Raman tuning sets the pump powers and DFB VOA
attenuation to achieve the target gain.
• Manual mode: User disables Raman tuning and manually configures the Raman pumps and DFB VOA
attenuation.
When Raman tuning is in progress, the node performing Raman tuning triggers the
RAMAN-TUNE-IN-PROGRESS alarm. From Cisco IOS XR Release 7.9.1, NCS 1010 supports C+L band
networks. In a C+L band configuration, the RAMAN-TUNE-IN-PROGRESS alarm is raised at the C-band
OLT or ILA node performing Raman tuning as well as the far end L-band node. OSRI disables the EDFA
amplifiers on both the C and L band devices in the peer node during Raman Tuning.
Raman Tuning
2
Raman Tuning
Overview of Raman Tuning
Note • If Raman back reflection (BR) is high, Raman tuning turns the Raman pumps off and goes into blocked
state. High BR can damage the optics. When you clear the high BR and BR is at acceptable levels, the
system triggers Raman tuning and turns the Raman pumps on.
• If a Raman span has a span loss value less than 14 dB, Raman tuning goes into the BLOCKED state.
The NCS 1010 performs a span loss check at system startup to verify if you can use Raman amplification
effectively on the span.
View Raman Tuning Status
You can view the Raman tuning status using show olc raman-tuning command. The following sample is an
output of the show olc raman-tuning command.
RP/0/RP0/CPU0:ios#sh olc raman-tuning
Tue Mar 21 06:11:36.944 UTC
Controller : Ots0/0/0/0
Raman-Tuning Status : TUNED
Tuning Complete Timestamp : 2023-03-20 07:54:00
Estimated Max Possible Gain : 19.8 dB
Raman Gain Target : 16.0 dB
Gain Achieved on Tuning Complete : 15.7 dB
You can view the Raman tuning status for individual controllers using show olc raman-tuning controller
ots r/s/i/p command. The following sample is an output of the show olc raman-tuning controller ots r/s/i/p
command.
RP/0/RP0/CPU0:ios#sh olc raman-tuning controller ots 0/0/0/0
Tue Mar 21 06:13:26.535 UTC
Controller : Ots0/0/0/0
Raman-Tuning Status : TUNED
Tuning Complete Timestamp : 2023-03-20 07:54:00
Estimated Max Possible Gain : 19.8 dB
Raman Gain Target : 16.0 dB
Gain Achieved on Tuning Complete : 15.7 dB
You can view detailed Raman tuning status using show olc raman-tuning details command. The following
sample is an output of the show olc raman-tuning details command.
RP/0/RP0/CPU0:ios#show olc raman-tuning details
Tue Mar 21 06:27:13.302 UTC
Controller : Ots0/0/0/0
Raman-Tuning Status : TUNED
Tuning Complete Timestamp : 2023-03-20 07:54:00
Estimated Max Possible Gain : 19.8 dB
Raman Gain Target : 16.0 dB
Gain Achieved on Tuning Complete : 15.7 dB
Last Run Fail Reason : [ Peer node is unreachable ]
Last Run Fail Timestamp : 2023-03-19 12:20:37
Last Successful Tuning Gain : 15.7 dB
Last Successful Tuning Timestamp : 2023-03-20 07:54:00
You can view detailed Raman tuning status for individual controllers using show olc raman-tuning details
controller ots r/s/i/p command. The following sample is an output of the show olc raman-tuning details
controller ots r/s/i/p command.
Raman Tuning
3
Raman Tuning
Overview of Raman Tuning
RP/0/RP0/CPU0:ios#show olc raman-tuning details controller Ots 0/0/0/0
Tue Mar 21 06:27:58.213 UTC
Controller : Ots0/0/0/0
Raman-Tuning Status : TUNED
Tuning Complete Timestamp : 2023-03-20 07:54:00
Estimated Max Possible Gain : 19.8 dB
Raman Gain Target : 16.0 dB
Gain Achieved on Tuning Complete : 15.7 dB
Last Run Fail Reason : [ Peer node is unreachable ]
Last Run Fail Timestamp : 2023-03-19 12:20:37
Last Successful Tuning Gain : 15.7 dB
Last Successful Tuning Timestamp : 2023-03-20 07:54:00
To view the individual Raman pump information and other parameters, use the show controllers ots r/s/i/p
raman-info command.
RP/0/RP0/CPU0:ios#show controllers ots 0/0/0/0 raman-info
Fri Apr 1 06:40:33.849 UTC
Alarm Status:
-------------
Detected Alarms: None
Alarm Statistics:
-----------------
RAMAN-AUTO-POW-RED = 0
RAMAN-1-LOW-POW = 0
RAMAN-2-LOW-POW = 0
RAMAN-3-LOW-POW = 0
RAMAN-4-LOW-POW = 0
RAMAN-5-LOW-POW = 0
RAMAN-1-HIGH-POW = 1
RAMAN-2-HIGH-POW = 0
RAMAN-3-HIGH-POW = 0
RAMAN-4-HIGH-POW = 0
RAMAN-5-HIGH-POW = 0
Parameter Statistics:
---------------------
Raman Safety Control mode = auto
Raman Osri = OFF
Raman Force Apr = OFF
Composite Raman Power = 886.60 mW
RAMAN Pump Info:
---------------------
Instance Wavelength(nm) Power(mW)
1 1424.00 257.60
2 1438.00 255.10
3 1457.00 71.60
4 1470.00 127.50
5 1495.00 170.10
Configured Parameters:
-------------
Raman Safety Control mode = auto
Raman Osri = OFF
Raman Force Apr = OFF
RAMAN Pump Info:
Raman Tuning
4
Raman Tuning
Configure Raman Tuning
---------------------
Instance Power(mW)
1 45.00
2 40.00
3 40.00
4 40.00
5 35.00
The following sample output
Note In the previous output, there are two sections for Raman Pump Info that show different values. The first Raman
Pump Info section displays operational data (current pumps power values). The second Raman Pump Info
section displays Raman Pump Power configuration. In this case, the default pump powers are displayed. Use
the raman-tx-power pumpvaluevalue command to configure individual Raman pump powers.
The Raman tuning application locks the OTDR scan at both fiber ends before the tuning starts, and releases
the lock after the tuning completes. Therefore, when you try to start the OTDR scan when Raman tuning is
running, your request gets rejected. The following example explains the OTDR start request rejection. The
OTDR scan request that has been rejected already does not run automatically after the lock is released, so you
have to create a new request to start the OTDR again.
Configure Raman Tuning
The following configurations are available for Raman Tuning:
Disable Raman Tuning
You can disable Raman tuning for a controller. Use the following commands to disable Raman tuning.
configure
optical-line-control
controller ots Rack/Slot/Instance/Port
raman-tuning disable
commit
end
The following is a sample configuration that disables Raman tuning.
RP/0/RP0/CPU0:ios#configure
RP/0/RP0/CPU0:ios(config)#optical-line-control
RP/0/RP0/CPU0:ios(config-olc)#controller ots 0/0/0/0
RP/0/RP0/CPU0:ios(config-olc-ots)#raman-tuning disable
RP/0/RP0/CPU0:ios(config-olc-ots)#commit
RP/0/RP0/CPU0:ios(config-olc-ots)#end
Enable Raman Tuning
You can enable Raman tuning for a controller. Use the following commands to enable Raman tuning.
configure
optical-line-control
Raman Tuning
5
Raman Tuning
Configure Raman Tuning
controller ots Rack/Slot/Instance/Port
raman-tuning enable
commit
end
The following is a sample configuration that enables Raman tuning.
RP/0/RP0/CPU0:ios#configure
RP/0/RP0/CPU0:ios(config)#optical-line-control
RP/0/RP0/CPU0:ios(config-olc)#controller ots 0/0/0/0
RP/0/RP0/CPU0:ios(config-olc-ots)#raman-tuning enable
RP/0/RP0/CPU0:ios(config-olc-ots)#commit
RP/0/RP0/CPU0:ios(config-olc-ots)#end
Configure Raman Gain Target
You can manually set the desired Raman gain target. Use the following commands to set the Raman gain
target.
configure
optical-line-control
controller ots Rack/Slot/Instance/Port
raman-tuning raman-gain-target value
commit
end
You can configure Target Raman Gain of 8.0 to 25.0 dB in multiples of 0.1 dB. The following is a sample
configuration that configures the Raman gain target to 18 dB.
RP/0/RP0/CPU0:ios#configure
RP/0/RP0/CPU0:ios(config)#optical-line-control
RP/0/RP0/CPU0:ios(config-olc)#controller ots 0/0/0/0
RP/0/RP0/CPU0:ios(config-olc-ots)#raman-tuning raman-gain-target 180
RP/0/RP0/CPU0:ios(config-olc-ots)#commit
RP/0/RP0/CPU0:ios(config-olc-ots)#end
Configure Raman Pump Powers
You can set the Raman pump powers manually. Use the following commands to set the pump powers.
configure
controller ots Rack/Slot/Instance/Port
raman-tx-power pumpvaluevalue
commit
end
The following is a sample configuration that sets the pump power of the first Raman pump to 211 mW.
RP/0/RP0/CPU0:ios#configure
RP/0/RP0/CPU0:ios(config-olc)#controller ots 0/0/0/0
RP/0/RP0/CPU0:ios(config-olc-ots)#raman-tx-power 1 value 21100
RP/0/RP0/CPU0:ios(config-olc-ots)#commit
RP/0/RP0/CPU0:ios(config-olc-ots)#end
Raman Tuning
6
Raman Tuning
Configure Raman Tuning
Configure DFB VOA Attenuation
Raman tuning algorithm changes the DFB VOA to adjust the DFB Tx power depending on the span loss. The
following table lists the DFB TX power for different span loss ranges.
Span DFB TX
Loss Power
14-25 -5 dB
dB
25-33 0 dB
dB
>33 dB 5 dB
Use the following commands to configure DFB VOA attenuation when Raman Tuning is disabled and you
want to configure the DFB manually.
configure
controller dfb Rack/Slot/Instance/Port
tx-voa-attenuation value
commit
end
The following is a sample configuration that sets the DFB VOA attenuation to 10 dB.
RP/0/RP0/CPU0:ios#conf
Wed Jul 6 04:45:47.720 UTC
RP/0/RP0/CPU0:ios(config)#controller dfb 0/0/0/0
RP/0/RP0/CPU0:ios(config-Dfb)#tx-voa-attenuation 100
RP/0/RP0/CPU0:ios(config-Dfb)#commmit
RP/0/RP0/CPU0:ios(config-Dfb)#end
Initiate Raman Tuning
You can trigger Raman tuning manually. Use the following exec command to trigger Raman tuning.
olc start-raman-tuning controller ots Rack/Slot/Instance/Port
The following is a sample configuration that initiates Raman tuning.
RP/0/RP0/CPU0:ios#olc start-raman-tuning controller ots 0/0/0/0
Raman Tuning
7
Raman Tuning
Raman Tuning with OTDR Lock
Raman Tuning with OTDR Lock
Table 1: Feature History
Feature Name Release Information Description
Raman Tuning with OTDR Lock Cisco IOS XR Release 7.10.1 If the OTDR scan and Raman
tuning are performed on the same
fiber simultaneously, the OTDR
reports unexpected results.
In this release, a check is being
implemented to prevent both
operations from running
simultaneously. The Raman tuning
application imposes an OTDR lock
at both ends of the fiber before the
process starts and releases the same
after the tuning is completed.
The OTDR scan and Raman tuning cannot be simultaneously executed on the same fiber. To resolve this
issue, Raman tuning application locks the OTDR at both ends of the fiber before the tuning process starts and
releases the lock after the tuning completes.
If the OTDR scan is in progress, the lock request is rejected and the Raman tuning application retries every
minute to acquire the OTDR lock. The Raman tuning starts only when OTDR scan lock is acquired at both
ends of the fiber. If the Raman tuning application is running, user request to start OTDR scan is rejected. See
Start OTDR.
The following sample shows the blocked status of the Raman Tuning due to OTDR running in remote node.
RP/0/RP0/CPU0:ios#show olc raman-tuning
Tue Feb 28 10:32:12.648 UTC
Controller : Ots0/0/0/0
Raman-Tuning Status : BLOCKED
Blocked Reason Details : [ Raman peer response OSRI ON/OTDR LOCK ON failure ]
Tuning Complete Timestamp : N/A
Estimated Max Possible Gain : N/A dB
Raman Gain Target : N/A dB
Gain Achieved on Tuning Complete : N/A dB
The following sample shows the blocked status of the Raman Tuning due to OTDR running in local node.
P/0/RP0/CPU0:ios#sh olc raman-tuning
Tue Feb 28 10:39:18.055 UTC
Controller : Ots0/0/0/0
Raman-Tuning Status : BLOCKED
Blocked Reason Details : [ Raman local OTDR LOCK ON failure ]
Tuning Complete Timestamp : N/A
Estimated Max Possible Gain : N/A dB
Raman Gain Target : N/A dB
Gain Achieved on Tuning Complete : N/A dB
Raman Tuning
8
