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Extremely high jitter in SLA

jzhang135
Level 1
Level 1

Hello,

We recently switched to a T1 connection for a remote site, all of a sudden the Jitter Time in our IP SLA jumped to as high as 77 million (from 1 or 2... not million, just one or two). Does anything look wrong? Here's the config & stat output:

ip sla 10

icmp-jitter 10.xx.xx.xx num-packets 20 interval 40

frequency 600

ip sla schedule 10 life forever start-time now

Round Trip Time (RTT) for       Index 10

Type of operation:              icmpJitter

        Latest RTT: 8 milliseconds

Latest operation start time: *22:36:54.404 UTC Thu Dec 9 2010

Latest operation return code: Over threshold

RTT Values:

        Number Of RTT: 20               RTT Min/Avg/Max: 8/8/11

Latency one-way time:

        Number of Latency one-way Samples: 0

        Source to Destination Latency one way Min/Avg/Max: 0/0/0

        Destination to Source Latency one way Min/Avg/Max: 0/0/0

Jitter Time:

        Number of Jitter Samples: 19

        Source to Destination Jitter Min/Avg/Max: 77815000/77815000/77815000

        Destination to Source Jitter Min/Avg/Max: 77815000/77815000/77815001

Packet Late Arrival: 0

Out Of Sequence: 0

        Source to Destination: 0        Destination to Source 0

        In both Directions: 10

Packet Skipped: 0

Packet Loss: 0

        Loss Period Length Min/Max: 0/0

Number of successes: 0

Number of failures: 1

Operation time to live: Forever

Thank you for any input!

James

3 Replies 3

Joe Clarke
Cisco Employee
Cisco Employee

What version of IOS is this? How many collectors are configured on this device?  Verify that the clock is the same on both the source and the target.  This typically means NTP.

Version 12.3(8r)YH12 (model 1811 remote site), Version 12.4(13r)T11 (model 3825, primary router). There are two IP SLAs configured. The second one (IP SLA 20) is normal. Here's the statistics for the second one to compare. The funny part is the route to the IP address in the IP SLA 20 goes through the first IP address (primary router) in IP SLA 10.

Round Trip Time (RTT) for       Index 20

Type of operation:              icmpJitter

        Latest RTT: 19 milliseconds

Latest operation start time: 13:52:25.339 UTC Mon Dec 13 2010

Latest operation return code: OK

RTT Values:

        Number Of RTT: 20               RTT Min/Avg/Max: 19/19/31

Latency one-way time:

        Number of Latency one-way Samples: 0

        Source to Destination Latency one way Min/Avg/Max: 0/0/0

        Destination to Source Latency one way Min/Avg/Max: 0/0/0

Jitter Time:

        Number of Jitter Samples: 19

        Source to Destination Jitter Min/Avg/Max: 0/0/0

        Destination to Source Jitter Min/Avg/Max: 1/1/1

Packet Late Arrival: 0

Out Of Sequence: 0

        Source to Destination: 0        Destination to Source 1

        In both Directions: 0

Packet Skipped: 0

Packet Loss: 0

        Loss Period Length Min/Max: 0/0

Number of successes: 3

Number of failures: 0

Operation time to live: Forever

The routers' times are not set with NTP. They are set manually, the remote site was about a few minutes off (compared to the primary router). I've manually set it to within 1 second time now. But that didn't fix the issue.

Any other settings that could affect this?

Thanks again for the help!

James

These versions look like boot loader code vs. system IOS.  Please post show versions from both routers.