We use SolarWinds to monitor our IP SLA operations. I've created several UDP VOIP jitter operations similar to:
ip sla 40001
udp-jitter 10.10.10.10 32768 source-ip 10.11.11.11 codec g711ulaw
threshold 1000
These operations work great, and we have ip sla responder enabled on the opposite side. Recently we noticed a high amount of packet loss in our SolarWinds graphs, but I'm not sure how to correlate that to a statistic on the CLI. This is occurring on multiple paths leaving our voice gateway, so it does not appear to be a single link causing the problem. A statistic output indicates:
VGW#show ip sla statistics 40014
IPSLAs Latest Operation Statistics
IPSLA operation id: 40014
Type of operation: udp-jitter
Latest RTT: 53 milliseconds
Latest operation start time: 12:44:30 GMT Wed Sep 14 2016
Latest operation return code: OK
RTT Values:
Number Of RTT: 676 RTT Min/Avg/Max: 51/53/70 milliseconds
Latency one-way time:
Number of Latency one-way Samples: 0
Source to Destination Latency one way Min/Avg/Max: 0/0/0 milliseconds
Destination to Source Latency one way Min/Avg/Max: 0/0/0 milliseconds
Jitter Time:
Number of SD Jitter Samples: 675
Number of DS Jitter Samples: 675
Source to Destination Jitter Min/Avg/Max: 0/1/6 milliseconds
Destination to Source Jitter Min/Avg/Max: 0/1/17 milliseconds
Over Threshold:
Number Of RTT Over Threshold: 0 (0%)
Packet Loss Values:
Loss Source to Destination: 0
Source to Destination Loss Periods Number: 0
Source to Destination Loss Period Length Min/Max: 0/0
Source to Destination Inter Loss Period Length Min/Max: 0/0
Loss Destination to Source: 0
Destination to Source Loss Periods Number: 0
Destination to Source Loss Period Length Min/Max: 0/0
Destination to Source Inter Loss Period Length Min/Max: 0/0
Out Of Sequence: 0 Tail Drop: 324
Packet Late Arrival: 0 Packet Skipped: 3182
Voice Score Values:
Calculated Planning Impairment Factor (ICPIF): 1
MOS score: 4.34
Number of successes: 37
Number of failures: 0
Operation time to live: Forever
Cisco notes: "Tail drops are an indication that the IP SLA device is stressed beyond its capacity. Reduce the number of operations, packets per second speed by increasing the packet size of the probes and monitor the results."
We have only a few SLA operations on this router (ten total running every 60 seconds), and cpu is holding steady around 10-15%, memory at 40%.
So my question is, would tail drops be translated into packet loss in this scenario? The packets skipped counter has not incremented since I began checking this particular operation.
Throwing packets since 2012
