IP SLA Parameters

When configuring IP SLA, there are several parameters that can be used to modify the behavior of the operation. The following context sensitive help shows these parameters for use with the icmp-echo SLA feature:

R1(config-ip-sla)#icmp-echo 192.168.12.2 
R1(config-ip-sla-echo)#?  
IP SLAs Icmp Echo Configuration Commands:
  default            Set a command to its defaults
  exit               Exit operation configuration
  frequency          Frequency of an operation
  history            History and Distribution Data
  no                 Negate a command or set its defaults
  owner              Owner of Entry
  request-data-size  Request data size
  tag                User defined tag
  threshold          Operation threshold in milliseconds
  timeout            Timeout of an operation
  tos                Type Of Service
  verify-data        Verify data
  vrf                Configure IP SLAs for a VPN Routing/Forwarding instance

Some of the most commonly used parameters include:

• frequency - indicates how often the ICMP echo request will be sent out in seconds.
• threshold - specifies after how much time a "reaction event" takes place, such as considering a particular SLA as "down." In simpler terms, for an icmp-echo SLA, it is the amount of time that must pass without a successful ping before the SLA is considered down.
• timeout - the amount of time an IP SLA will wait for a response from its echo request packet.

Typically, for an ICMP echo request SLA, the following should be true:

(frequency seconds ) > (timeout milliseconds ) > (threshold milliseconds )

Otherwise, it may be that the SLA will always fail, even if the link is actually up.

Links:

https://networklessons.com/cisco/ccie-routing-switching/ip-sla-service-level-agreement-on-cisco-ios/

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipsla/command/sla-cr-book/sla_s2.html#wp4194409343

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipsla/command/sla-cr-book/sla_s2.html#wp3249187301

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipsla/command/sla-cr-book/sla_a1.html#wp4022386755