First, the discussion you are referencing (if it is the one I remember seeing a while back) was specific to how NPM sends ICMP packets to nodes, and how many of those packets are used to calculate metrics. This is not to be confused with Cisco IP SLA operations, which are generated and processed between routers. The difference is subtle, but extremely important.
Secondly, ICMP and UDP Jitter operation types have a default of 10 packets sent per operation. You can however change this at will by using the num-packets command in IP SLA template configuration mode. I have entered an excerpt from the Cisco Command Reference for your review below.
It would be safe to assume that the base of the calculation you are referencing in your chart is always the default 10. But I would highly recommend verifying this on your router configuration to ensure that a non-default entry has not been made.
If default, then you can rely on the following:
- 10 packets are sent between routers during each processed IP SLA Jitter-type operation (TCP or UDP)
- Every time stamp in your result-set represents a base of 10
- 60% packet loss = 6 out of 10 packets were lost in transmission (reasons may vary depending on the environment)
To specify the number of packets for a jitter operation in an auto IP Service Level Agreements (SLAs) operation template, use the num-packetscommand in the appropriate submode of the IP SLA template parameters configuration mode. To return to the default, use the no form of this command.
Number of packets to be sent in each operation. Range is 1 to 60000. Default is 10 per operation.
Default is 10 packets.
ICMP jitter configuration (config-icmp-jtr-params)
UDP jitter configuration (config-udp-jtr-params)
This command was introduced.
This command changes the number of packets sent during a jitter operation from the default (10) to the specified number of packets.
You must configure the type of IP SLAs operation, such as User Datagram Protocol (UDP) jitter or ICMP jitter, before you can configure any other parameters of the operation.
Before you can use this command to configure auto IP SLAs operation templates, you must enter the parameters command in IP SLA template configuration mode.
The following example shows how to configure an auto IP SLAs operation template for an ICMP jitter operation to change the number of packets from the default to 20 packets:
Router(config)#ip sla auto template type ip icmp-jitter 1 Router(config-tplt-icmp-jtr)#parameters Router(config-icmp-jtr-params)#num-packets 20 Router(config-icmp-jtr-params)#end Router# show ip sla auto template type ip icmp-jitter IP SLAs Auto Template: 1 Measure Type: icmp-jitter Description: IP options: Source IP: 0.0.0.0 VRF: TOS: 0x0 Operation Parameters: Number of Packets: 20 Inter packet interval: 20 Timeout: 5000 Threshold: 5000 Statistics Aggregation option: Hours of statistics kept: 2 Statistics Distributions options: Distributions characteristics: RTT Distributions bucket size: 20 Max number of distributions buckets: 1 Reaction Configuration: None
ip sla auto template
Begins configuration for an IP SLAs operation template and enters IP SLA template configuration mode.
show ip sla auto template
Displays configuration including default values of an auto IP SLAs operation template.
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Thank you for the information.
I believe my IP SLA operations setting on the router is using default setting -- 10 packets are sent between routers during each processed.
If the base is 10, then the % in the graph should only be showing 10%,20% , etc. ( multiple of 10%. )
And why would I have sth 6%, 8% in the graph?
Thanks in advance