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I've been looking into skypes protocol or what people can make out since its a propriety protocol. I've read "An analysis of the skype peer-to-peer internet telephony protocol", though it is old it discusses a certain property which I'm looking to recreate in my own architecture. What I'm interested in is during video a conference, data is sent to one machine (the one most likely with the best bandwidth and processing power) which then redistributes to the other machines.

What is not explained is what happens when the machine receiving and sending the data has unexpectedly dropped out. Of course rather than drop the conference it would be best to find another machine to carry on receiving and distributing the data. Is there any documentation on how this performed on skype or a similar peer-to-peer VoIP?

Basically I'm looking for the fastest method to detect when a "super peer" unexpectedly drops out and quickly migrating operations to another machine.

Tsume
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You need to set a timeout (i.e., limit) and declare that if you don't receive communication within then, the communication is either dead (no path between the peers, reachability issue) or the remote peer is down. There is no other method.

If you have direct tcp or other connection to the super peer, you can catch events telling you the connection dies too. If your communication is relayed, and your framework automatically attempt to find a new route to your target peer, it will either find one or never find out. Hence, the necessity for a timeout.

If none hears about someone for some time, they are finally considered/declared dead.

Jérôme Verstrynge
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