Timeout is the maximum time required for SLA operation to complete - for example the timeout waiting for probe response. Threshold is boundary value measured ove the operation RESULT (e.g. RTT, or jitter value collected during the opearation). Crossing threshold usually means SLA contract violation. Note that these two values apply to DIFFERENT objects.
Timeout is directly used to restart the operation. Threshold is used to activate a response to IP SLA violation, e.g. send SNMP trap or start seconday SLA operation.
You should configure the sla based on Frequency > Timeout > Threshold.
For Cisco.com
Q. What does the term threshold and timeout in IP SLA operation mean?
A. Threshold sets the rising threshold that generates a reaction event and stores history information for an IP SLAs operation.
Timeout sets the amount of time an IP SLAs operation waits for a response from its request packet.
Example:
If you configure Timeout > Threshold, you can see the RTT and if the RTT exceed Threshold, it is a failure. If you configure Threshold > Timeout, if the RTT exceed timeout but less than Threshold, it won't show the RTT but it is still a failure.
So failure is RTT exceed either Timeout or Threshold.
ip sla monitor 1
type echo protocol ipIcmpEcho 115.0.0.1
timeout 500
threshold 20
frequency 10
Rack1R6#show ip sla monitor statistics
Round trip time (RTT) Index 1
Latest RTT: 36 ms
Latest operation start time: *04:12:47.001 UTC Mon Mar 4 2002
Latest operation return code: Over threshold
Number of successes: 0
Number of failures: 6
Operation time to live: Forever
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