First let me start with I have very little experience with IP SLA jitter operations. I've used SLA's for awhile for PBR, but that's pretty much it. Cisco defines jitter as (IP SLAs Configuration Guide, Cisco IOS Release 15M&T - Configuring IP SLAs UDP Jitter Operations [Support] - Cisco):
Jitter means inter-packet delay variance. When multiple packets are sent consecutively from source to destination, for example, 10 ms apart, and if the network is behaving ideally, the destination should be receiving them 10 ms apart. But if there are delays in the network (like queuing, arriving through alternate routes, and so on) the arrival delay between packets might be greater than or less than 10 ms. Using this example, a positive jitter value indicates that the packets arrived greater than 10 ms apart. If the packets arrive 12 ms apart, then positive jitter is 2 ms; if the packets arrive 8 ms apart, then negative jitter is 2 ms. For delay-sensitive networks like VoIP, positive jitter values are undesirable, and a jitter value of 0 is ideal.
I've configured an IP SLA sender (branch office 4510) to a responder (HQ 3750) to measure/track jitter and troubleshoot possible congestion across our MPLS circuits between the two sites. VNQM successfully added the preconfigured IP SLA operation but the data I get back just looks like round trip times relabled as "Jitter" by the app unless I'm missing something. On the VNQM homepage under "Latency and Jitter" I have 0 latency with 14ms Jitter. Is this a true positive jitter measurement? Also, for Bidirectional jitter I have a measurement for "Source --> Target" and "Target --> Source". The previous is 20ms with the later being 1ms. How do I read this? Is this a true measurement of the variance Cisco describes or should it be read differently? If it helps, the SLA sender is configured as such:
Entry number: 3
Owner:
Tag: VoIP
Operation timeout (milliseconds): 5000
Type of operation to perform: udp-jitter
Target address/Source address: 1.1.1.1/2.2.2.2
Target port/Source port: 5000/0
Type Of Service parameter: 0x0
Request size (ARR data portion): 32
Packet Interval (milliseconds)/Number of packets: 20/10
Verify data: No
Vrf Name:
Control Packets: enabled
Schedule:
Operation frequency (seconds): 60 (not considered if randomly scheduled)
Next Scheduled Start Time: Start Time already passed
Group Scheduled : FALSE
Randomly Scheduled : FALSE
Life (seconds): Forever
Entry Ageout (seconds): never
Recurring (Starting Everyday): FALSE
Status of entry (SNMP RowStatus): Active
Threshold (milliseconds): 5000
Distribution Statistics:
Number of statistic hours kept: 2
Number of statistic distribution buckets kept: 1
Statistic distribution interval (milliseconds): 20
Enhanced History:
