A bug on the IPSLA measures has been detected on some versions of Cisco IOS 15.X.
An IPSLA bug affecting some versions of Cisco IOS 15.X has been detected resulting in the report of incoherent network delays.
The bug concerns the IPSLA Responder that may be enabled on routers of your operators. The responder implements the measure IPSLA Jitter that calculates the network delays or RTT (Round Trip Time).
Result: an incoherent RTT, which can be fixed at 1ms or variable but with low values. The RTT is the time to reach the target and the time for the target to respond. In the affected versions, it does not match at all.
Example of results with incoherent measures related to Cisco bug:
- A measure with a time to reach and return of 80ms and 100ms gives a 20ms RTT!
- A measure with a constant 1ms RTT, time to reach and return of 80ms and 100ms time!
- A measure between France and Australia with a 10ms RTT!
List of the versions which correct this bug
The Cisco support has confirmed this bug and given the following list of versions not affected by the bug:
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