Cisco 7600 Series Ethernet Services Plus (ES+) and Ethernet Services Plus T (ES+T) Line Card Configuration Guide
Configuring Automatic Laser Shutdown
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Table Of Contents

Configuring Automatic Laser Shutdown

Configuring Automatic Laser Shutdown

Restrictions and Usage Guidelines

Verification

Examples


Configuring Automatic Laser Shutdown


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.


Configuring Automatic Laser Shutdown

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.

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.

Restrictions and Usage Guidelines

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.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface tengigabitethernet

4. als

5. als restart {mode | pulse}

6. als restart mode {automatic | manual}

7. als restart pulse {interval 100-20000 | width 2-200}

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:
Router# enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

interface tengigabitethernet

Example:

Router(config)# interface tengigabitethernet 2/1

Enters interface mode.

Step 4 

als

Example:

Router(config-if)# als

Enables ALS.

Step 5 

als restart {mode | pulse}

Example:

Router(config-if)# als restart

Request an ALS restart mode.

Step 6 

als restart mode {automatic | manual}

Example:

Router(config-if)# als restart mode automatic

Selects the ALS restart mode.

Step 7 

als restart pulse {interval 100-20000 | width 2-200}

Example:

Router(config-if)# als restart pulse interval 2000

Selects the ALS pulse mode.

Verification

Use the following commands to verify operation.

Command
Purpose

Router# show als {all | interface}

Displays ALS shutdown status for all or selected interfaces.


Examples

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>
 
 
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
 
 
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#