After you schedule the operation with the ip sla schedule command, you cannot change the configuration of the operation. To change the configuration of the operation, use the no form of the ip sla global configuration command and reenter the configuration information.
If the operation is in a pending state, you can define the conditions under which the operation makes the transition from pending to active with the ip sla reaction-trigger and ip sla reaction-configuration global configuration commands. When the operation is in an active state, it immediately begins collecting information.
The following time line shows the age-out process of the operation:
W is the time the operation was configured with the ip sla global configuration command.
X is the start time or start of life of the operation (that is, when the operation became “active”).
Y is the end of life as configured with the ip sla schedule global configuration command (life seconds have counted down to zero).
Z is the age out of the operation.
Age out starts counting down at W and Y, is suspended between X and Y, and is reset to its configured size at Y.
The operation to can age out before it executes (that is, Z can occur before X). To ensure that this does not happen, configure the difference between the operation’s configuration time and start time (X and W) to be less than the age-out seconds.
The total RAM required to hold the history and statistics tables is allocated at the time of scheduling the IP SLAs operation. This prevents router memory problems when the router gets heavily loaded and lowers the amount of overhead an IP SLAs operation causes on a router when it is active.
The recurring keyword is supported only for scheduling single IP SLAs operations. You cannot schedule multiple IP SLAs operations using the ip sla schedule command. The life value for a recurring IP SLAs operation should be less than one day. The ageout value for a recurring operation must be “never” (which is specified with the value 0), or the sum of the life and ageout values must be more than one day. If the recurring option is not specified, the operations are started in the existing normal scheduling mode.
The ip sla schedule command is supported in IPv4 networks. This command can also be used when configuring an IP SLAs operation that supports IPv6 addresses.
In the following example, operation 25 begins actively collecting data at 3:00 p.m. on April 5. This operation will age out after 12 hours of inactivity, which can be before it starts or after it has finished with its life. When this operation ages out, all configuration information for the operation is removed (that is, the configuration information is no longer in the running configuration in RAM).
ip sla schedule 25 life 43200 start-time 15:00 apr 5 ageout 43200
In the following example, operation 1 begins collecting data after a 5-minute delay:
ip sla schedule 1 start-time after 00:05:00
In the following example, operation 3 begins collecting data immediately and is scheduled to run indefinitely:
ip sla schedule 3 start-time now life forever
In the following example, operation 15 begins automatically collecting data every day at 1:30 a.m.:
ip sla schedule 15 start-time 01:30:00 recurring