C H A P T E R
11
This chapter provides information about configuring Automatic Laser Shutdown (ALS) on the Cisco
7600 Series Ethernet Services Plus (ES+) and Ethernet Services PlusT (ES+T) line cards on the
Cisco 7600 series router.
ALS can be configured on the following Cisco 7600 Series ES+ Extended Transport (ES+XT) line cards and Cisco 7600 Series ES+ Transport (ES+T) line cards:
•
•
•
•
•
•
•
•
76-ES+XT-2TG3CXL
76-ES+XT-4TG3CXL
76-ES+T-2TG
76-ES+T-4TG
76-ES+XC-20G3C
76-ES+XC-20G3CXL
76-ES+XC-40G3C
76-ES+XC-40G3CXL
For more information about the commands in this chapter, see the Cisco IOS Release 12.2 SR Command
References at http://www.cisco.com/en/US/products/ps6922/prod_command_reference_list.html
.
Note Unless otherwise specified, the information provided in this chapter is applicable to ES+XT, ES+T and
ES+XC line cards. ALS is supported on ES+XC line cards from SRE1 release.
Automatic Laser Shutdown (ALS) is a technique used to automatically shut down the output power of the transmitter in case of fiber break according to ITU-T G.664. This is a safety feature that prevents dangerous levers of laser light from leaking out of a broken fiber, provided ALS is provisioned on both ends of the fiber pair.
The sequence of events is as follows. If a fiber is cut, the receiver will detect a Loss Of Signal (LOS).
The ALS agent will turn off the transmitter. The receiver at the far end will then detect an LOS and its
ALS agent will turn off the transmitter. In this way the entire fiber will go dark.
After the fiber is believed to have been repaired, the transmitters can be restarted. To restart, one of the transmitter lasers is turned on (pulsed) for a provisionable amount of time. If the LOS clears at the far-end receiver, the far-end transmitter will be restarted. The near-end will clear its LOS and at this point both transmitters will be on and both LOS alarms will be cleared.
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Chapter 11 Configuring Automatic Laser Shutdown
If a break remains in the fiber, one or both LOS alarms will remain and the transmitters will be disabled.
The near-end transmitter will turn off at the end of its pulse.
There are two types of restart: manual and automatic. In manual restart, you can request a single restart pulse from the ALS agent. In automatic restart, the ALS agent sends a periodic restart pulse; the period is configurable.
ALS functions in the following modes:
•
•
Disabled mode—If mode is disabled, ALS is disabled. LOS will not cause laser shutdown.
Manual restart mode—The laser is turned off when the ALS agent detects an LOS for 500 ms. After
ALS is engaged, a manual command is issued that turns on the laser for the time period of the pulse width. The laser is turned on when the LOS has been cleared for 100 ms.
• Automatic restart mode—The laser is shut down for the time period of pulse spacing when the ALS agent detects a LOS for 500 ms. Then, the laser automatically turns on for the time period of the selected pulse width. If an LOS still exists at that time, the laser is shut down again. This pattern continues until the LOS is cleared for 100 ms; then, the laser will stay on.
5.
6.
7.
3.
4.
1.
2.
enable configure terminal interface tengigabitethernet als als restart { mode | pulse } als restart mode { automatic | manual } als restart pulse { interval 100-20000 | width 2-200 }
Command or Action
Step 1 enable
Example:
Router# enable
Step 2 configure terminal
Purpose
Enables privileged EXEC mode.
• Enter your password if prompted.
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 interface tengigabitethernet
Example:
Router(config)# interface tengigabitethernet
2/1
Enters interface mode.
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Command or Action
Step 4 als
Purpose
Enables ALS.
Example:
Router(config-if)# als
Step 5 als restart { mode | pulse } Request an ALS restart mode.
Example:
Router(config-if)# als restart
Step 6 als restart mode { automatic | manual } Selects the ALS restart mode.
Example:
Router(config-if)# als restart mode automatic
Step 7 als restart pulse { interval 100-20000 | width
2-200 }
Selects the ALS pulse mode.
Example:
Router(config-if)# als restart pulse interval
2000
Use the following commands to verify operation.
Command
Router# show als { all | interface }
Purpose
Displays ALS shutdown status for all or selected interfaces.
The following are examples of ALS configuration commands:
Router(config)# interface t2/1
Router(config-if)# als ?
<cr>
Router(config-if)# als
Router(config-if)# do show running inter t2/1
Building configuration...
Current configuration : 59 bytes
!
interface TenGigabitEthernet2/1
no ip address
als end
Router(config-if)# als ?
restart Specify ALS parameters
<cr>
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Router(config-if)# als restart ?
mode Specify ALS mode
pulse Specify the ALS PULSE
Router(config-if)# als restart mode ?
automatic Select automatic mode
manual Select manual mode
Router(config-if)# als restart mode manual ?
<cr>
Router(config-if)# als restart mode manual
Router(config-if)# als restart pulse ?
interval Specify the width of the ALS PULSE
width Specify the width of the ALS PULSE
Router(config-if)# als restart pulse interv ?
<100-20000> ALS pulse interval in seconds
Router(config-if)# als restart pulse interv 150
Router(config-if)# als restart pulse width ?
<2-200> ALS pulse width in seconds
Router(config-if)# als restart pulse width 100
Router(config-if)# do show runn inter t2/1
Building configuration...
Current configuration : 116 bytes
!
interface TenGigabitEthernet2/1
no ip address
als
als restart mode manual
als restart pulse interval 150 end
Router(config-if)# end
Router# show als ?
all ALS information for all interfaces
interface Interface
Router# show als interface t2/1 ?
| Output modifiers
<cr>
Router# show als interface t2/1
TenGigabitEthernet2/1
Mode ALS_MODE_MANUAL
Pulse Width 100 sec
Pulse Interval 150 sec
Current state ALS_STATE_NORMAL
Router# show als all
TenGigabitEthernet2/1
Mode ALS_MODE_MANUAL
Pulse Width 100 sec
Pulse Interval 150 sec
Current state ALS_STATE_NORMAL
TenGigabitEthernet2/2
Mode ALS_MODE_AUTOMATIC
Pulse Width 100 sec
Pulse Interval 300 sec
Current state ALS_STATE_NORMAL
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Router#
Router# hw-module ?
interface Interface
module Apply command to a module component
subslot Control a component in a subslot
Router# hw-module inter t2/1 ?
als Automatic Laser Shutdown
Router# hw-module inter t2/1 als ?
restart restart ALS for the given inteface
Router# hw-module inter t2/1 als restart ?
<cr>
Router# hw-module inter t2/1 als restart
Router#
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