BBB Lag issues and constant reconnects

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Chad Lohmeyer

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Oct 26, 2016, 1:39:46 PM10/26/16
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We have started having trouble with BBB when we use it with our students. We get kicked out many times during a 45 minutes session and we have frequent lag issues with audio and visual items.

We have students that are hardwired to our network (gigabit connection) that are having these issues. They are using the latest version of Google Chrome. 

Does anyone have any suggestions for what we can do?

Thanks,
Chad

Fred Dixon

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Oct 27, 2016, 12:11:09 PM10/27/16
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Hi Chad,

One thing to check is the presentation that is uploaded to the session.  If it contains a very smooth gradient, it sometimes gets converted into a very large SWF file (1000's of individual images) that can cause all the clients to lag, and some to get disconnected.

Can you check on the presentation that was uploaded during the session and see if it has a very smooth gradient background.

If you upload a copy of it to BigBlueButton and everything starts to lag, you have the reason.  You an adjust the number of images that BigBlueButton will allow in a slide by adjusting the setting in bigbluebutton.properties on your server.

See



Let us know if the above helps and, if not, we'll keep digging further.


Regards,... Fred


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Chad Lohmeyer

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Oct 27, 2016, 12:31:37 PM10/27/16
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Hi Fred,

We are not uploading any presentations to BBB. The only feature that we are using is the shared desktop and the camera views. The students that appear on the webcams are frozen 90% of the time in the conference and the shared desktop is very slow, they see updates to the screen about once every 30 seconds. We have around 11 total people in the conference including the teacher.

Thanks,
Chad


On Thursday, October 27, 2016 at 12:11:09 PM UTC-4, Fred Dixon wrote:
Hi Chad,

One thing to check is the presentation that is uploaded to the session.  If it contains a very smooth gradient, it sometimes gets converted into a very large SWF file (1000's of individual images) that can cause all the clients to lag, and some to get disconnected.

Can you check on the presentation that was uploaded during the session and see if it has a very smooth gradient background.

If you upload a copy of it to BigBlueButton and everything starts to lag, you have the reason.  You an adjust the number of images that BigBlueButton will allow in a slide by adjusting the setting in bigbluebutton.properties on your server.

See



Let us know if the above helps and, if not, we'll keep digging further.


Regards,... Fred

On Wed, Oct 26, 2016 at 10:39 AM, Chad Lohmeyer <cmloh...@tsc.k12.in.us> wrote:
We have started having trouble with BBB when we use it with our students. We get kicked out many times during a 45 minutes session and we have frequent lag issues with audio and visual items.

We have students that are hardwired to our network (gigabit connection) that are having these issues. They are using the latest version of Google Chrome. 

Does anyone have any suggestions for what we can do?

Thanks,
Chad

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Chad Pilkey

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Oct 27, 2016, 1:22:54 PM10/27/16
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If you connect to demo.bigbluebutton.org from both inside and outside your network and try desktop sharing and webcams you might be able to narrow down if it's specifically networking related. Also are you seeing "[Tunnelling]" in the lower right corner? You can get frequent disconnects if your users are have to go through port 80 for everything.

Fred Dixon

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Nov 10, 2016, 6:45:12 AM11/10/16
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Hi Chad,

> The students that appear on the webcams are frozen 90% of the time in the conference and the shared desktop is very slow, they see updates to the screen about once every 30 seconds.


We recently encountered a similar case where the desktop sharing was updating very slowing for remove viewers.  The problem turned out to be the upstream bandwidth for the presenter sharing their desktop.

We did a test with the presenter, who said their ISP provided 3 Mbits/sec upstream and 6 Mbits/sec downstream, and were just sharing slides.  At some point, we noticed noticed their audio became momentarily garbled and we asked them to do a quick speed tests (http://speedtest.net).  They were seeing only 0.52 Mbits/sec upload at that time.

The key point here is its not what the ISP is provide that is important; rather, it's the actual bandwidth that is the key.

For desktop sharing, we recommend that a presenter have (at least) 1.0 Mbits/sec actual bandwidth for upload.  Of course, that's not an absolute number -- the results of what users see will depend also what the presenter is sharing (does their screen update frequently?), how big of an area or full-screen they are sharing, and whether the presenter is also sharing their webcam.

Audio doesn't take much bandwidth, but it is susceptible to network lag, and the more constrained the bandwidth becomes, the more packet lag increase.

The increased packet lag can eventually affect connectivity.   The BigBlueButton client checkes about once each second (a "heartbeat") to make sure it's still connected with the server.  

There is some tolerance for this check, but, like Skype which will disconnect and attempt to reconnect, the BigBlueButton client will attempt to reconnect if the heartbeat fails. 


> We are not uploading any presentations to BBB. The only feature that we are using is the shared desktop and the camera views. 

Is the presenter on a Mac or PC?  On the PC, the desktop sharing support sharing a region of the screen.  Recommend they try selecting a subset of their screen for desktop sharing.

On Mac, the desktop sharing will default to sharing the main screen.  Recommend the presenter reduce the resolution on their main screen before sharing their desktop.

I can't say for certain the above is going to fix the issue -- it does sound like a bandwidth issue and, at some point, when the bandwidth gets too low, there really isn't enough left to share the desktop.  

Is the presenter using desktop sharing to share?  If so, we recommend saving the slides as PDF and uploading them to the presentation area -- this will use far less bandwidth as each client will cache the slides.  If possible, avoid having a high-def image as a background to the slides -- this significantly increases the size of each slide and may also increase the conversion time.   If they can share slides using the built-in presentation capabilities, then for times they need to share their desktop (such as demonstrating an application), use the pause/resume capability of the desktop sharing.

Let us know if the above helps!

Regards,... Fred


On Thu, Oct 27, 2016 at 1:22 PM, Chad Pilkey <capi...@gmail.com> wrote:
If you connect to demo.bigbluebutton.org from both inside and outside your network and try desktop sharing and webcams you might be able to narrow down if it's specifically networking related. Also are you seeing "[Tunnelling]" in the lower right corner? You can get frequent disconnects if your users are have to go through port 80 for everything.


On Thursday, October 27, 2016 at 12:31:37 PM UTC-4, Chad Lohmeyer wrote:
Hi Fred,

We are not uploading any presentations to BBB. The only feature that we are using is the shared desktop and the camera views. The students that appear on the webcams are frozen 90% of the time in the conference and the shared desktop is very slow, they see updates to the screen about once every 30 seconds. We have around 11 total people in the conference including the teacher.

Thanks,
Chad

On Thursday, October 27, 2016 at 12:11:09 PM UTC-4, Fred Dixon wrote:
Hi Chad,

One thing to check is the presentation that is uploaded to the session.  If it contains a very smooth gradient, it sometimes gets converted into a very large SWF file (1000's of individual images) that can cause all the clients to lag, and some to get disconnected.

Can you check on the presentation that was uploaded during the session and see if it has a very smooth gradient background.

If you upload a copy of it to BigBlueButton and everything starts to lag, you have the reason.  You an adjust the number of images that BigBlueButton will allow in a slide by adjusting the setting in bigbluebutton.properties on your server.

See



Let us know if the above helps and, if not, we'll keep digging further.


Regards,... Fred

On Wed, Oct 26, 2016 at 10:39 AM, Chad Lohmeyer <cmloh...@tsc.k12.in.us> wrote:
We have started having trouble with BBB when we use it with our students. We get kicked out many times during a 45 minutes session and we have frequent lag issues with audio and visual items.

We have students that are hardwired to our network (gigabit connection) that are having these issues. They are using the latest version of Google Chrome. 

Does anyone have any suggestions for what we can do?

Thanks,
Chad

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