VC issues across WAN

[carl_townshend]

Hi All

We have a site in the UK and one in India, we have a 10Mbit MPLS between the 2 sites.

We have Cisco VC equipment running across this link, with QOS enabled all the way through, also by the provider!

We are having intermittant voice and video dropouts between the sites, I did a VC test last week and I also saw it happen! the screen goes scrambed and then goes back to clear! and occassionaly the voice went!

I put ip sla on the core switch in the UK, recorded the following detail!

Is there any other things I should be looking at to sort these issues? should VC be near perfecr across these long distance MPLS links?

Round Trip Time (RTT) for       Index 10
Type of operation: jitter
        Latest RTT: 178 ms
Latest operation start time: 09:16:12.509 UTC Thu Jan 8 2015
Latest operation return code: OK
RTT Values:
        Number Of RTT: 992
        RTT Min/Avg/Max: 176/178/191 milliseconds
Latency One-Way Time:
        Number of Latency one-way Samples: 992
        Source to Destination Latency one way Min/Avg/Max: 86/88/96 milliseconds
        Destination to Source Latency one way Min/Avg/Max: 89/90/101 milliseconds
Jitter Time:
        Number of SD Jitter Samples: 985
        Number of DS Jitter Samples: 986
        Source to Destination Jitter Min/Avg/Max: 0/2/9 milliseconds
        Destination to Source Jitter Min/Avg/Max: 0/2/11 milliseconds
Packet Loss Values:
        Loss Source to Destination: 8           Loss Destination to Source: 0
        Out Of Sequence: 0      Tail Drop: 0
        Packet Late Arrival: 0  Packet Skipped: 0
Voice Score Values
        Calculated Planning Impairment Factor (ICPIF): 1
        Mean Opinion Score (MOS): 4.34
Number of successes: 79
Number of failures: 0
Operation time to live: Forever
 

[Joseph W. Doherty]

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The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

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Posting

To your question whether the VC should be "near perfect", well that depends on whether you SLA's define "near perfect".  Your MPLS vendor should be at least meeting the agreed/contracted SLAs.

You can pursue verification of SLAs are being met, but SLAs also often depend on you meeting your usage agreement too.

I've seen issues where MPLS providers have actual internal issues which you often have to prove to them because most often performance issues are on the user side.  (I agree.)  So, you might also want to carefully review your design, implementation and actual usage.  (Or retain a consultant, with the proper expertise, for such a review.)

[carl_townshend]

should we be getting drop outs though? the latency and jitter looks good!

any more thoughts?

I am thinking of getting a company in to run some voip / video testing etc using some special probes and software ?

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Well you can get drops while latency and jitter look good if there's congestion with shallow buffers/queues.  (On high speed links, drops are often common because of shallow [relatively speaking] buffers/queues.  Your VC is 10Mbps, but what are the physical links being used by your MPLS provider.)

You could get a company in to test.  Assuming they too see the problem(s), what do you do next?  You still may need a consultant anyway.  So the real question is whether you start with additional tests or whether you start with the consultant.  The latter, may also desire some additional testing but such might be more focused than just additional generic testing that only confirms you have an issue.  (Of course, the company that you chose to test, might also consult.  Additional testing first, isn't so bad, but I think you want someone that can focus on how things should be, and test to confirm they are or are not rather than test to confirm there's a problem but don't know how to troubleshoot it. - Am I making any sense?)