but the IGMP packet wasn't sent yet. So we are receiving answers before we managed to effectly 
join the multicast group.

Here an example (tshark) with is a is_alive query: 

1 0.000000000  10.77.3.105 → 224.0.29.200 UDP 120 1236 → 1236 Len=78   <-- notify is_alive
2 0.000033024  10.77.3.105 → 224.0.29.200 UDP 150 1236 → 1236 Len=108  <-- request is_alive
3 0.007238730  10.77.3.105 → 224.0.29.200 IGMPv2 46 MRG 224.0.29.200   <-- Multicast join

The average delay is around 8ms on a container based install (with 802.1q, and bridges) 
The only solution right now is to wait (50ms) in AsycnNetworkConnector.connect().

After the patch, you should experience something like this: 

1 0.000000000  10.77.3.105 → 224.0.29.200 IGMPv2 46 MRG 224.0.29.200
2 0.043197464  10.77.3.105 → 224.0.29.200 UDP 120 1236 → 1236 Len=78
3 0.043218241  10.77.3.105 → 224.0.29.200 UDP 150 1236 → 1236 Len=108
4 0.046509230   10.77.3.64 → 224.0.29.200 UDP 122 1236 → 1236 Len=80
5 0.047613517   10.77.3.64 → 224.0.29.200 UDP 122 1236 → 1236 Len=80
6 0.049329272   10.77.3.64 → 224.0.29.200 UDP 123 1236 → 1236 Len=81

Yes, first device answers within 3.3ms.. so < 8ms. 

This bug only occurs on host with no other xAAL apps running on the same address/port and only
at startup.




git-svn-id: https://redmine.imt-atlantique.fr/svn/xaal/code/Python/branches/0.7@3145 b32b6428-25c9-4566-ad07-03861ab6144f