To enable link noise monitoring on a clear channel T1 link on Cisco 10000 series routers, use the t1span  command in controller configuration mode. To disable link noise monitoring, use the no  form of this command. 
                           
                           
                        
                        
                           
                           t1 channel span  {minor-warn | remove | major-warn}  [duration seconds | lcv threshold  [pcv threshold]  [set | clear]] 
                           
                           no t1 channel span  {minor-warn | remove | major-warn}  [duration seconds | lcv threshold  [pcv threshold]  [set | clear]] 
                           
                           
                        
                        
                           Syntax Description
                           
                           
                              
                              
                                 
                                 
                              
                              
                                 
                                    | 
                                          
                                             channel
                                              
                                          
                                        | 
                                          Number that indicates the T1 channel. The range is from 1 to 28.
                                        | 
                                 
                                    | 
                                          minor-warn
                                        | 
                                          Enables minor warning messages for noisy T1 links. 
                                        | 
                                 
                                    | 
                                          major-warn
                                        | 
                                          Enables major warning messages for noisy T1 links.
                                        | 
                                 
                                    | 
                                          remove
                                        | 
                                          Enables removal of noisy T1 links from a multilink bundle.
                                        | 
                                 
                                    | 
                                          
                                             lcv
                                              
                                          
                                             threshold
                                              
                                          
                                        | 
                                          Specifies the line code violation (LCV) threshold value in bit error per second. The valid range on a T1 link is 5 to 1544
                                          seconds. The valid range on an E1 link is 7 to 2048 seconds. 
                                        
                                          
                                             
                                                The default LCV value for minor-warn on a T1 link is 154 seconds and on E1 link is 205 seconds.
                                             
                                             
                                                The default LCV value for major-warn or removal on a TI link is 1544 seconds and on E1 link is 2048 seconds.
                                              | 
                                 
                                    | 
                                          
                                             duration
                                              
                                          
                                             seconds
                                              
                                          
                                        | 
                                          Specifies the number of consecutive seconds that a threshold is exceeded or improved for a condition to occur. The valid range
                                          on a T1/E1 link is 4 to 600 seconds. The default value for T1 and E1 links is 10 seconds.
                                        | 
                                 
                                    | 
                                          
                                             pcv
                                              
                                          
                                             threshold
                                              
                                          
                                        | 
                                          Specifies the number of timeslots in error per second. The valid range on a T1 link is 3 to 320 seconds and on an E1 link
                                          is 8 to 832 seconds.
                                        
                                          
                                             | Note | 
                                                      A T1 link has 24 timeslots and an E1 link has 32 timeslots.
                                                    |  
                                          
                                             
                                                The default path code violation (PCV) value for minor-warn on a T1 link is 145 seconds and on E1 link is 205 seconds.
                                             
                                             
                                                The default PCV value for major-warn or removal on a TI link is 320 seconds and on E1 link is 832 seconds.
                                              | 
                                 
                                    | 
                                          set
                                        | 
                                          (Optional) Specifies the set condition. Set is used as the default when no conditions are given.
                                        | 
                                 
                                    | 
                                          clear
                                        | 
                                          (Optional) Specifies the clear condition.
                                        | 
                              
                           
                           
                        
                        
                           Command Default
                           
                           
                              Link Noise Monitoring on any T1 or E1 link is disabled by default. If enabled without specifying any thresholds, the default
                              values are used as mentioned in the Syntax Description.
                           
                           
                        
                        
                           Command Modes
                           
                           
                              Controller configuration (config-controller)
                           
                           
                        
                        
                           
                           Command History
                           
                              
                              
                                 
                                 
                              
                              
                                 
                                    | 
                                          Release
                                        | 
                                          Modification
                                        | 
                              
                              
                                 
                                    | 
                                          12.2(33)XNE
                                        | 
                                          This command was introduced.
                                        | 
                              
                           
                           
                        
                        
                           Usage Guidelines
                           
                           
                              Note the following when configuring link noise monitoring on T1 and E1 links: 
                           
                           
                           
                              - 
                                 
                                    The major-warn  and remove  keywords cannot be used at the same time; disable one to use the other.
                                  
- 
                                 
                                    If the warn  and remove  keywords are specified without any other options, the LCV and PCV thresholds and duration defaults are used to determine
                                    set (set ) and clear (clear ) conditions. 
                                  
- 
                                 
                                    If the span  command is issued with the set  keyword and the command is not issued again with the clear  keyword, or vice versa, the values configured for the threshold and duration is used for both keywords. 
                                  
- 
                                 
                                    If the span  command is issued without the set  or clear  keywords specified, set  is the default keyword. 
                                  
- 
                                 
                                    The set  and clear  keywords can be specified only if the threshold values for the LCV and/or duration is specified. 
                                  
- 
                                 
                                    The threshold for a clear condition must be less than the threshold for a set condition.
                                  
- 
                                 
                                    The threshold for a warn event must be less than the threshold for a remove event.
                                  
- 
                                 
                                    The duration is calculated in seconds and is the number of consecutive seconds by which either of the thresholds (exceed or
                                    improve) must be surpassed for a condition to occur.
                                  
- 
                                 
                                    For events, the BER on a line should be greater than or equal to (>=) the thresholds for exceed condition. For improve condition,
                                    BER has to be less than (<) the threshold.
                                  
- 
                                 
                                    If the PCV threshold is not configured (using the pcv  keyword and value), this threshold is calculated by the linear extrapolation of the Gaussian probability that is representative
                                    of most noise environments based on the configured LCV threshold. If the LCV threshold is specified, it is not mandatory to
                                    specify the PCV threshold. 
                                  
Examples
                           
                           
                              The following example shows how to generate an exceed event for a minor warning, if the number of LCVs on the T1 line remain
                              above or equal to 20, or the number of PCVs remains above or equal to 10 for 10 continuous seconds. 
                           
                           
Router(config-controller)# t1 1 span minor-warn lcv 20 pcv 10 duration 10 set
                           
                              The following example shows how to generate an improve event for a minor warning, if the number of LCVs on the T1 line remain
                              below 15 or the number of PCVs remain below 8 for 20 continuous seconds. 
                           
                           
Router(config-controller)# t1 1 span minor-warn lcv 15 pcv 8 duration 20 clear
                           
                              The following example shows the same threshold value being used by the set  and clear  conditions, when both keywords are not specified. In this example, the threshold value is 80 for both conditions.
                           
                           
Router(config-controller)# t1 1 span major-warn lcv 150 pcv 100 duration 80
Router(config-controller)# end
Router# show running-config | section controller sonet 7/0/0
controller SONET 7/0/0
 framing SONET
 path 1 controller t3
 clock source internal
controller T3 7/0/0.1
 t1 1 channel-group 0 timeslots 1-24
 t1 1 span minor-warn lcv 150 pcv 100 duration 80 set
t1 1 span minor-warn lcv 150 pcv 100 duration 80 clear
                           
                              The following example shows how the threshold value specified for the clear condition is used by the set condition when set
                              condition is not specified. In this example, the threshold value of 100 specified for the clear condition is used for the
                              set condition.
                           
                           
Router(config-controller)# t1 1 span major-warn lcv 100 pcv 70 duration 100 clear
Router(config-controller)# end
Router# show running-config | section controller sonet 7/0/0
controller SONET 7/0/0
 framing SONET
 path 1 controller t3
 clock source internal
controller T3 7/0/0.1
t1 1 channel-group 0 timeslots 1-24
 t1 1 span minor-warn lcv 100 pcv 70 duration 100 set
 t1 1 span minor-warn lcv 100 pcv 70 duration 100 clear
                           
                              The following is a sample output showing the details of the calculated PCV threshold value. The calculated PCV value is 141:
                           
                           
Router# debug c10k lnm
Router(config-controller)# t1 1 span major-warn lcv 150
Router(config-controller)# end
*Sep 10 20:34:43.923:  T1 extrapolation: pcv_delta=130 lcv_delta=139 factor=140 pcv_const=14
 computed pcv_threshold = 141
*Sep 10 20:34:43.923: CMD for minor-warn set
*Sep 10 20:34:43.923: clear taking set thresholds
*Sep 10 20:34:43.923: T3 7/0/0.1#1 setting values to be sent to LC for WARN ENABLE 3
*Sep 10 20:34:43.923: 
 3, 150, 150, 141, 141, 10, 10, 0, 0, 0, 0, 0, 0
Router# show running-config | section controller sonet 7/0/0
controller SONET 7/0/0
 framing SONET
 path 1 controller t3
 clock source internal
controller T3 7/0/0.1
 t1 1 channel-group 0 timeslots 1-24
 t1 1 span minor-warn lcv 150 pcv 141 duration 10 set
 t1 1 span minor-warn lcv 150 pcv 141 duration 10 clear