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IP SLA packet loss reported in VNQM, but not from Cisco CLI

pwz over 7 years ago

I have about 10 IP SLA operations (voip udp jitter) running on a Cisco ISR4k router. Up until Monday it experienced only brief packet loss, and always below 5%. A change was made to our voip infrastructure on Saturday, which pushed most of our inbound/outbound calls through this router.

Starting Monday we began seeing high packet loss on our IP SLA operations sourced from this router, which probe to other routers. The packet loss is being reported at 20-80% throughout the day, stopping at night, and resuming the next morning when people show up in the office.

It definitely seems as if the change made has impacted our monitoring, but I'm not seeing higher cpu or memory utilization in NPM. I'd like to be able to correlate the packet loss we're seeing to a CLI output to either prove or disprove the operations are being affected. When I run "show ip sla statistics <operation number>", I only see tail drops and packet skipped counters, though the packet skipped does not increment. Tail drop seems to fluctuate between 0 and as much as 600-700. The CLI output shows no packet loss whatsoever no matter how many times I check.

Am I looking in the wrong place? How does Solarwinds determine packet loss here if the Cisco CLI doesn't show any?

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pwz over 7 years ago in reply to orionfan +2

Yup, we had to add them manually. I forget where I found that information, though it was likely another forum post somewhere here on Thwack. The format you'd need is: ip sla <operation number> udp-jitter…

0 orionfan over 7 years ago

Hi,
How did you get the IP SLA to work on the ISR4K? Did you create the IP SLA manually on the router, and then run the IP SLA Operations Wizard to add it to VNQM? We did a router refresh and are looking at introducing our IP SLA's again.

Thanks!
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0 pwz over 7 years ago in reply to orionfan

Yup, we had to add them manually. I forget where I found that information, though it was likely another forum post somewhere here on Thwack. The format you'd need is:
ip sla <operation number>
udp-jitter <destination ip> <source port> source-ip <your router's ip> codec g711ulaw
threshold <your threshold>
We decided to use 32768 for the source port and g711ulaw as the codec to simulate voice traffic. Once you create the operation, make sure the destination router has "ip sla responder" turned on. After that it should be successful and give you the ip sla info you want. You can then manually enter the node and operation number into solarwinds, where it will begin graphing it as any other operation.
Still waiting for the new VNQM version so we can do this automatically... any day now....
..any day...
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