Table Of Contents
Serial Link Parameter Monitoring and Control
Information About Serial Link Parameter Monitoring and Control
Major and Minor Monitoring Intervals
snmp-server enable traps if-monitor
Serial Link Parameter Monitoring and Control
This feature monitors parameters on various physical links (PA-4T, PA-4T+, PA-8T-XX, PA-A3-XX, PA-MC-8T1 and PA-MC-8E1) and sends traps/execute control actions based on the values of the monitored parameters. This feature is supported on FSIP.
Feature Specifications for the Serial Link Parameter Monitoring and Control
12.3(1)
This feature was introduced.
For platforms supported in Cisco IOS Release 12.3(1), consult Cisco Feature Navigator.
Finding Support Information for Platforms and Cisco IOS Software Images
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Contents
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Information About Serial Link Parameter Monitoring and Control
Information About Serial Link Parameter Monitoring and Control
To configure Serial Link Parameter Monitoring and Control, you need to understand the following concepts:
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Monitoring
This feature is designed to monitor the occurrences of various parameters on the PA-4T+, PA-8T-232, PA-8T-V35, PA-A3-T3/E3/OC3, PA-MC-8T1/E1, CX-FSIP8 port adapters in Cisco 7500 series routers. The monitoring algorithm counts the occurrences of these error and non-error parameters in a configurable monitoring time interval. It also compares the counts with configured thresholds (low and high); if the count of a parameter exceeds the configured lower threshold, then a trap is sent identifying the corresponding parameter and the interface. If the count of a parameter exceeds the configured higher threshold in the monitoring interval, a trap is sent.
The link is shut down if the restart mechanism is enabled; subsequently, in an attempt to make the link operational again, the link is restarted (after a configurable restart delay). If the link is not brought up this would be considered as a failed restart attempt. Another attempt will be made to restart the link after another restart delay and so on. Also if the high threshold is reached/exceeded again, within the first major monitoring interval since the link was brought up, the link will be shut down again. This would also be considered as a failed restart attempt.
The number of consecutive failed restart attempts could be configured to have an upper limit which when exceeded would cause the link to be shut permanently.
The word trap and notification have been used interchangeably while discussing the traps that are sent when a particular threshold is reached/exceeded. The CISCO-IF-MONITOR-NOTIF MIB will be used to send the traps. Information of the last trap sent from a particular interface could be obtained via this MIB. The MIB would also maintain the total number of traps sent by the SNMP agent (this particular router). This count would be included in the trap sent to the NMS. NMSs should track the value of this object (cIfMonNotifCount) received in each notification. If the difference in the value of this object across two consecutive notifications is more than one, a notification has been delayed, dropped, lost or routed out of sequence. The only reliable way to recover such notifications is via the NOTIFICATION-LOG-MIB. The NMS should preferably configure/create a log in the NOTIFICATION-LOG-MIB to capture notifications sent when a particular threshold is reached/exceeded. If possible, a named log should be created. When a notification loss is detected, the NMS can then poll the log to determine which notification was lost.
Major and Minor Monitoring Intervals
A major monitoring interval consists of a number of minor monitoring intervals. Every minor monitoring interval the parameter count for the last major monitoring interval is compared with the predefined (high or low) thresholds. You can set the number of minor intervals per major interval using the link monitor samples command.
Restart Delay
The restart delay is the amount of time which the software waits before it attempts to restart a link that was shut down. This usually occurs because the high threshold limit for a particular parameter on the link was reached or exceeded in the monitoring interval and the shut down configuration option was enabled (i.e., the restart mechanism is enabled). Another attempt will be made to restart the link after another restart delay if the link was not brought up in the previous attempt.
Restart Attempts
The restart attempt specifies the upper limit on number of allowed consecutive failed restart attempts. The link is shut down if the restart mechanism is enabled and the high threshold has been reached or exceeded; subsequently, in an attempt to make the link operational again, the link is restarted (after a configurable restart delay). If the link is not brought up this would be considered as a failed restart attempt. Another attempt will be made to restart the link after another restart delay and so on. Also, if the high threshold is reached/exceeded again, within the first major monitoring interval since the link was brought up, the link will be shut down again. This would also be considered as a failed restart attempt. The number of back-to-back failed restart attempts could be configured to have an upper limit which when exhausted would cause the link to be shut permanently since no more attempts will be made to restart the link.
The link has to be brought up again if monitoring of parameters on the link needs to be resumed for a link, which is down. If the restart attempts is set to '0' then no attempt will be made to restart the link once it is brought down by the algorithm.
Additional References
For additional information related to Serial Link Parameter Monitoring and Control, refer to the following references:
Related Documents
Additional router configuration commands
Cisco IOS Configuration Fundamentals Command Reference, Release 12.3
Standards
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.
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1 Not all supported standards are listed.
MIBs
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To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
1 Not all supported MIBs are listed.
RFCs
Technical Assistance
Command Reference
This section documents new and modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.3 command reference publications.
New Commands
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debug link monitor
To display the statistics of the executing process, use the debug link monitor command in privileged EXEC mode. To disable debug link monitor, use the no form of this command.
debug link monitor
no debug link monitor
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values.
Command Modes
Privileged EXEC
Command History
Usage Guidelines
This command is used to display the statistics, which are used for debugging the status of the various conditions occurred during execution of the monitoring process.
Examples
The following example enables link monitoring statistics:
Router# debug link monitor%DEBUG-ENABLED Error Rate Link MonitorThe following example disables link monitoring statistics:
Router# no debug link monitor%DEBUG-DISABLED Error Rate Link MonitorRelated Commands
link monitor
To set error rate limits and monitoring interval, use the link monitor command in interface configuration mode. To disable link monitor, use the no form of this command.
link monitor {aborts | crc | disc | drops | flaps | frame-reject | frmr | runts | sabm}
no link monitor {aborts | crc | disc | drops | flaps | frame-reject | frmr | runts | sabm}
link monitor {aborts | crc | disc | drops | flaps | frame-reject | frmr | runts | sabm} interval interval
link monitor {aborts | crc | disc | drops | flaps | frame-reject | frmr | runts | sabm} interval interval threshold high high low low
Syntax Description
Defaults
Command Modes
Global configuration.
Command History
Usage Guidelines
If the Major interval or high/low thresholds are not mentioned then their default values are used. The user will get the option to reset the value to the default or keep it as the previously set value if and only if the user has previously set the value which is something other than the default and the user does not enter the value while changing other parameters.
While configuring thresholds, all three values (interval, high and low threshold) should be configured together otherwise the default will be taken for the ones that are not actually configured. The high threshold should not be less than the lower threshold.
The X.25 parameters can be configured for monitoring only if X.25 is configured on the interface. X25 cannot be configured on the ATM port adaptors. When X.25 encapsulation is disabled, the timers for the configured X.25 parameters will continue to run. However, the parameter values will not be monitored which would imply that traps will not be sent. The user has to explicitly disable monitoring for any parameter in order to completely stop monitoring (which includes stopping the timers).
Examples
The following example shows setting the aborts interval and high and low thresholds:
Router(config-if)#link monitor aborts interval 100 threshold high 300 low 50Router(config-if)#link monitor abortsHigh Threshold current: 300 default: 100Reset the high threshold to the default value? [no]: yesLow Threshold current: 50 default: 10Reset the low threshold to the default value? [no]:Major Interval current: 100 default: 60Reset the major interval to the default value? [no]:link restart
To set the restart delay and restart attempts for the current link, use the link restart command in interface configuration mode. To disable link restart, use the no form of this command.
link restart attempts delay
no link restart
Syntax Description
Defaults
The default restart delay is 300 seconds.
Command Modes
Interface configuration.
Command History
Usage Guidelines
If any parameter (delay or attempts) is not explicitly mentioned, the default will be taken. The user will get the option to reset the value to the default or keep it as the previously set value if and only if the user has previously set the value which is something other than the default and the user does not enter the value while changing other parameters.
If the 'attempts' is configured as 0 then the link will be shut permanently the very first time the high threshold is reached/crossed. The delay value is of no use in this case.
The link has to be brought up again via no shut if monitoring of parameters on the link needs to be resumed for a link, which is brought down permanently by the restart mechanism.
If the link has been brought down by the link monitoring feature and the user enters shut or no link restart before a restart attempt is made, then the restart attempt will not be made and the link will continue to be down.
Examples
The following example shows the restart delay being set to 60 and the restart attempts to 10:
Router(config-if)#link restart delay 60 attempts 10link monitor samples
To set the number of minor intervals per major interval, use the link monitor samples command in global configuration mode. To disable link monitor samples, use the no form of this command.
link monitor {samples | parameters} interval
no link monitor samples
Syntax Description
interval
Minor intervals per major monitoring interval.
samples
Set the number of minor intervals per major interval.
parameters
Enable Link Monitoring for all configured parameters.
Defaults
The default restart delay is 300 seconds.
Command Modes
Global configuration.
Command History
Usage Guidelines
These commands can be used to fine tune the feature.
Examples
The following example shows setting the number of minor intervals per major interval to 5:
Router(config)#link monitor samples 5show interface link monitor
To show the link monitoring and restart configuration for all configured parameters for that interface., use the show interface link monitor command in EXEC configuration mode.
show interface interface name link {monitor | value}
Syntax Description
Defaults
No default behavior or values.
Command Modes
EXEC configuration.
Command History
Usage Guidelines
Use this command to show the various parameter values in the last major monitoring interval.
Examples
The following example shows the output from link monitoring on a serial interface:
Router#show interface serial 0/0/0 link monitorLINK PARAMETER MONITOR CONFIGURATIONEnabled-Parameter High-Threshold Low-Threshold Monitor-Interval(seconds)aborts 35 13 30crc 10000 10 60input-drops 1000 500 60flaps 3 2 60frame-rejects 100 10 60runts 10000 10 60Restart-Delay(seconds) 60 Restart-Attempts 2Number of Minor intervals per Major interval 5The following example shows the output from link monitoring on a serial interface:
Router#show interface serial 0/0/0 link valueaborts : 0crc : 0input-drops : 0flaps : 0frame-rejects : 0runts : 0show link monitor debug
To show the various statistics of the link monitoring and restart feature, use the show link monitor debug command in global configuration mode.
show link monitor debug
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values.
Command Modes
EXEC configuration.
Command History
Usage Guidelines
The statistics include the IPC messages sent to and received from the VIPs. It also includes the malloc failures, the number of times the link monitoring structure was found NULL, and the number of times the configuration of the RSP was not sent to the VIP during bootup of the VIP.
Examples
The following example shows the output from link monitoring on a serial interface:
Router#show link monitor debugLink Monitor Error StatisticsCONF STRUCTURE FOUND NULL...............0CONF STRUCTURE MALLOC FAIL..............0IPC SENT TOTAL..........................25IPC RECV TOTAL..........................3CCB CMD SENT TOTAL......................94LOVE LETTER RECV TOTAL..................1IPC SEND FAILURE........................1IPC RECV FAILURE........................0CCB CMD SEND FAILURE....................0LOVE LETTER RECV FAILURE................0CONFIG RESEND TO LC FAIL................0CHUNK ELEMENT FREE FAIL.................0CHUNK ELEMENT MALLOC FAIL...............0ELEMENTS IN TRAP QUEUE..................0TRAP FAIL ENQUEUE.......................0WATCHED QUEUE CREATEDCHUNK CREATEDTable 1 describes the significant fields shown in the display.
snmp-server enable traps if-monitor
To enable or disable the generation of a family of traps, use the snmp-server enable traps if-monitor command in global configuration mode. To disable snmp-server enable traps if-monitor, use the no form of this command.
snmp-server enable traps if-monitor
no snmp-server enable traps if-monitor
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values.
Command Modes
Global configuration.
Command History
Usage Guidelines
The if-monitor option enables the if-monitor red/yellow threshold traps for the link monitor feature. To enable the traps for a particular interface, the traps would have to be explicitly enabled on that interface in addition to the global command.
Examples
The following shows using the snmp-server enable traps if-monitor to enable if-monitor traps on all interfaces:
Router(config)#snmp-server enable traps if-monitorsnmp trap if-monitor
To enable the if-monitor traps for a particular interface, use the snmp trap if-monitor command in interface configuration mode. To disable snmp trap if-monitor, use the no form of this command.
snmp trap if-monitor
no snmp trap if-monitor
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values.
Command Modes
Interface configuration.
Command History
Usage Guidelines
Traps will be sent for a particular interface only if both the global and the interface commands are enabled.
Examples
The following shows using the snmp-server enable traps if-monitor to enable if-monitor traps on all interfaces:
Router(if-config)#snmp-server enable traps if-monitor
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