Bridge call causing intermittent blurring?

[Robert Passey]

All,

I have recently been experiencing problems with our oversea’s telepresence endpoints when performing MCU calls, the customer is complaining of an intermittent blurring on all oversea endpoints are on a bridge calls, all P2P call are good quality however.

The UK and oversea VPN’s have been designed differently due to the constraints of using a third party bearer, and I believe this to be the cause. However I would like to know if there are any changes I could possible make to the MCU (5310) or endpoints (SX20) to resolve this issue?

On a bridge call I checked the stats of the UK endpoint and this displayed good results;

•          0% packet loss TX
•          0.1% packet loss RX
•          3ms Jitter TX
•          2ms Jitter RX

I then asked the customer to check the stats of the US endpoint packet loss was at a good standard but the jitter values were a cause of concern:

•          0% packet loss TX
•          0.3 packet loss RX
•          1ms jitter TX
•          7ms intermittently raising to 19-24ms jitter on RX

Has anyone seen this type of issue before, and would be able to offer some advice?

Many thanks,

Rob

[Wayne DeNardi]

How's the bandwidth on the connection?  Is it getting congested when the calls are experiencing Jitter?  Do you have QoS configured on your endpoints / LAN / WAN?

What versions of the software are you running on your MCU and SX20s?  I know there was a participants appearing blury issue fixed in one of the new MCU software versions, but that may have only been for the 4200 series MCUs.

Wayne
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[Robert Passey]

Hi Wayne,

The link isn't congested according to the NOC, we have QoS AF21 on WAN, MCU and endpoints.

The MCU is on 5.4 and the endpoints are on TC6.3.

[Wayne DeNardi]

Are you sure it's 5.4 on the MCU?  The latest I can see available is 4.4(3.67).  From memory, it was in the upgrade from 4.4(3.57) to 4.4(3.67) that included a blury fix.

Wayne
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[Robert Passey]

Hi Wayne,

That's right we're on 4.4 (3.57), I have now upgraded to 4.4(3.67) and the symptoms persist.

Thanks again for the info.

Regards,

Rob

[Wayne DeNardi]

Hi Rob,

Some more things to check (if you haven't already:

What's the default bandwidth set at on your MCU, or for the conference you are using?

And, what's the Video format set to on the bridge - it is a SD/HD issue?

The Motion/Sharpness/Balanced tradeoff option as mentioned previously by Nick would be another place to look.  We have most of ours set to "Balanced" if that helps.

The P2P call would be going flat out at whatever bandwidth it can use, so would do High Definition if it can - is your MCU licenced for HD ports, and are HD ports being used for your "blurry" call, or is the "blurriness" because it's being stuck on an SD port?

Wayne
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[Robert Passey]

Hi Wayne, Nick,

Thanks for your help, the matter is now resolved. Networks came back to me confirming that there was an underlying bearer router with an interface at half duplex. As this supports our service by securely tunneling our VPN it didn't cause the usual packet loss and down speeding just increased jitter values.

Many thanks for your support.

Regards,

Rob

[Wayne DeNardi]

Thanks for letting us know the outcome of your troubleshooting Rob.  Hopefully it'll assist others who may have similar issues in the future searching the forums.

Glad to hear it's all fixed.

Wayne
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[Nick Halbert-Lillyman]

I've seen a similar effect, depending on the bandwidth of the call.

Using TP server, a call at 2560kbps would have noticable motion blur/artifacts whereas a point to point call at the same bandwidth would look much better.  Once you increase the call rate to 4Mbps - 6Mbps, it's much less noticable.

What call rate are you using?  You may be able to get some improvement by changing the endpoints and/or MCU to prefer "motion" over "sharpness" or visa versa.