I referred about icmp echo from ciscopress pages, still couldn't figure out the use of IP SLA ICMP ECHO in troubleshooting. Can anyone select the most appropriate one from the below options?
a. one way jitter measurement
b. packet-loss detection
c. hop-by-hop response time (I think that this is more related to icmp path echo's function)
d. congestion detection


  • I would select Answer "B". While I am sure there are many uses for this type of SLA, the uses I am familiar with are when you want to track reachability to some remote (non-connected) destination so you can send it frequent-and-repeated pings (via an SLA). If the SLA reports that the pings have stopped receiving a reply you now have knowledge that the remote device/interface is down (or you've lost a route to that destination).

    One use of this could be for use within HSRP. Two routers are running HSRP. Both routers also have uplink connections back into the Core of your network. You might have a requirement that the HSRP Active Router should ONLY be Active contingent upon its reachability to (the IP address of your Internet-facing router). So you could create an SLA that frequently pings Then you would create a "Track Object" that binds/associates this SLA to HSRP. Should your HSRP Active router discover (via the Track Object, that is monitoring the SLA) that is no longer responding to pings it could then significantly reduce its HSRP Priority, allowing the HSRP Standby router to preempt and assume the role of HSRP Active.

  • ICMP Echo Operation
    The ICMP Echo operation measures end-to-end response time between a Cisco router and any devices using IP. Response time is computed by measuring the time taken between sending an ICMP Echo request message to the destination and receiving an ICMP Echo reply.

    In the figure below ping is used by the ICMP Echo operation to measure the response time between the source IP SLAs device and the destination IP device. Many customers use IP SLAs ICMP-based operations, in-house ping testing, or ping-based dedicated probes for response time measurements.


    see https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipsla/configuration/15-mt/sla-15-mt-book/sla_overview-0.html

    see https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipsla/configuration/15-mt/sla-15-mt-book/sla_icmp_echo.html?referring_site=RE&pos=1&page=https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipsla/configuration/15-mt/sla-15-mt-book/sla_overview-0.html

  • Hi Martin Losik, response time and hop-by-hop response time are the same? If yes, the option C would be your choice. Right?

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