04-18-2022 04:18 PM
Hi,
I have a question on the ip sla icmp-echo operation. If an icmp response that isn't an echo reply (like destination unreachable) is received, will this result in an ip sla timeout return code?
Thanks
CC
Solved! Go to Solution.
04-18-2022 07:50 PM
Not that.
What I said is that, you may have response or not and unreacheble is considered 'not response' and will be counted as timeout.
I build this simples Lab when all routers speaks with each other using OSPF. From R4 to R5 I can ping successfully using loopback interface.
IPSLA was showing successes:
IPSLA operation id: 6
Type of operation: icmp-echo
Latest RTT: 48 milliseconds
Latest operation start time: *23:37:10.011 UTC Mon Apr 18 2022
Latest operation return code: OK
Number of successes: 2
Number of failures: 0
Operation time to live: Forever
Then, I went to R5 and I take the lookback interface off the OSPFprocess. This would cause ping unreachable on R4.
Then, the IP SLA registered the event as timeout and increase the "Number of failures" to 1.
IPSLA operation id: 6
Type of operation: icmp-echo
Latest RTT: NoConnection/Busy/Timeout
Latest operation start time: *23:38:10.011 UTC Mon Apr 18 2022
Latest operation return code: Timeout
Number of successes: 2
Number of failures: 1
Operation time to live: Forever
04-18-2022 06:02 PM
Destination unreacheable is an echo reply somehow.
Ip sla consider sucess and no sucess
04-18-2022 06:35 PM
Hi there,
Thanks for the reply,
icmp echo-reply is a specific response type code. This differs from the the other codes covering unreachable/prohibited etc.
Additionally, depending on the type these can be generated from a host in path rather than the destination host being targeted in the icmp-echo
Are you saying that ANY icmp response is treated as a success for ip sla ?
04-18-2022 07:50 PM
Not that.
What I said is that, you may have response or not and unreacheble is considered 'not response' and will be counted as timeout.
I build this simples Lab when all routers speaks with each other using OSPF. From R4 to R5 I can ping successfully using loopback interface.
IPSLA was showing successes:
IPSLA operation id: 6
Type of operation: icmp-echo
Latest RTT: 48 milliseconds
Latest operation start time: *23:37:10.011 UTC Mon Apr 18 2022
Latest operation return code: OK
Number of successes: 2
Number of failures: 0
Operation time to live: Forever
Then, I went to R5 and I take the lookback interface off the OSPFprocess. This would cause ping unreachable on R4.
Then, the IP SLA registered the event as timeout and increase the "Number of failures" to 1.
IPSLA operation id: 6
Type of operation: icmp-echo
Latest RTT: NoConnection/Busy/Timeout
Latest operation start time: *23:38:10.011 UTC Mon Apr 18 2022
Latest operation return code: Timeout
Number of successes: 2
Number of failures: 1
Operation time to live: Forever
04-18-2022 11:24 PM
IP SLA simple mechanism used to identify far the end is reachable or not in terms of reachability,
if the return code is OK then all is good, if the return code is anything else IP SLA treats as down, based on the action will be triggered.
04-19-2022 01:48 PM
Thanks for the clarification.
Very much appreciated with the effort (LAB setup) to confirm
Thanks
CC
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide