P2P connections die quickly under certain circumstances

[pal1000]

Conditions to replicate are rather unusual so please cope with me:

• an application using P2P connectivity is let to operate for a few minutes (5 minutes should be more than enough);
• you may close the P2P application when you want to get to the next step. Wherever you close the P2P application and its active connections won't make a difference;
• pause the VM execution for a few minutes (5 minutes should be more than enough);
• when resuming VM try to repeat the first step and witness the connection failure.

TCP connections seam unaffected. I only tested NAT network.

I reproduced this with ​Sopcast which is a P2P application.

• Install the latest version (4.2.0) in a Windows VM;
• Visit ​cooltvi.com in Internet Explorer and select a channel;
• Allow the ActiveX to run - this would start the live broadcast which is P2P based.

Sopcast requires Direct3D9 for video to render. But this is not required to reproduce this issue, it can very well be reproduced with black screen.

I could reproduce with Windows xp/posready 2009, 7, 8.1 and 10 guests. I tested with AMD PCNET Fast III, Intel PRO 1000 T-Server and MT Desktop, Paravirtualized Network.

I'll post logs if necessary.

[pal1000]

This may be a remnant of 6993.

[pal1000]

VM log with issue

[pal1000]

P2P connections recover if the VM is released from RAM. Any means would do:

• guest force power off;
• guest shutdown;
• guest save state.

When the VM is re-launched P2P connectivity is recovered.

It may also recover by using TCP connections for at least 5 minutes without releasing VM from RAM.

[Valery Ushakov]

Thanks for the report.

What do you mean by:

TCP connections seem unaffected.

Do you mean other TCP connections?

[pal1000]

I think SopCast uses UDP connections though I am not 100% certain. As I said it appears that using only TCP connections for 5 minutes allows P2P connectivity to recover. To be more precise after experiencing this issue I closed Internet Explorer waited a bit then tried again experiencing the same issue, then I watched an M3U8 HLS live stream for 5 minutes in Firefox in that same VM. After this I tried a SopCast stream again and surprisingly it worked with no issues. M3U8 HLS stream runs over HTTP so it's TCP based. ​Here is the Digi24 official live stream which is an M3U8 HLS live stream. This issue can be consistently replicated if steps are followed correctly.