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Replicated DMR Voice Packets

g8ptn@...
 

For general information, on a recent switch to a new DMR server, an observation was made that DVSwitch does not seem to cope with replicated voice packets.

The effect of the replicated packets is that the outgoing audio stream to DVSM sounds slow.


Whilst it is not desirable to have this situation in the network, my understanding is that the G4KLX software does deal with this by looking at a sequence number in the packets and drops replicated packets and replaces them with silence.


The cause of the replication has been fixed on the network in question, but it highlighted that it is also desirable to drop the replicated packets at the client side if possible.


I am not sure if the feature to drop can only be provided for the homebrew DMR protocol.


Dave (G8PTN)
Pierre Martel
 

I think it is a good idea to have a problem when there is packet duplication, cause the only reason I can think of for the cause of packet duplication is a loop into the network. Now if there is a loop, and the packets keep on being replicated and no one notices, and other loops come and now we would have 3,4,5 time the packet replicated the end result would be network congestion. Bandwidth is not of infinite supply. And looping does degrade network performance. So the best thing is to make sure there is no looping and the 'bug' won't happen. It is not because you can link multiple systems together that it is a good thing to actually link them.





Le ven. 11 déc. 2020 à 08:42, <g8ptn@...> a écrit :

For general information, on a recent switch to a new DMR server, an observation was made that DVSwitch does not seem to cope with replicated voice packets.

The effect of the replicated packets is that the outgoing audio stream to DVSM sounds slow.


Whilst it is not desirable to have this situation in the network, my understanding is that the G4KLX software does deal with this by looking at a sequence number in the packets and drops replicated packets and replaces them with silence.


The cause of the replication has been fixed on the network in question, but it highlighted that it is also desirable to drop the replicated packets at the client side if possible.


I am not sure if the feature to drop can only be provided for the homebrew DMR protocol.


Dave (G8PTN)
g8ptn@...
 

Hi Pierre,

Yes, I agree the situation is not desirable in the network. The actual issue was that packets were being duplicated; I don’t think it was a loop in this case.

Interestingly, I was the only person to spot the issue on DVSwitch and an old Openspot 1. Many stations are using Pi-Star MMDVM hotspots and there were no issues detected since the duplicated frames were being silently dropped.

Dave
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