Good news everyone !
One more time, FOG was not faulty but the NETWORK …
After checking again Forums on multicasting and similar problems, I’ve found the solution :
The querier switch must have an IP adress on the subnet …
Once I’ve made the change, I tested a 4 client multicast session : total success !
So I tried with a classroom of 19 clients : in 30 min ( 1.5Gbps/min, max speed with 100Mbits connections ), all images were downloaded !
So, maybe it would be interesting for others to include these advices in the wiki or the troubleshooting Multicast page :
- enable IGMP snooping on VLAN concerned in all switches
Choose 1 "master switch ( for me the all gigabit one under fogserver ) and make the following only for this one :
- assign an IP adress to the VLAN in the switch configuration in the subnet range
- enable IGMP query on the VLAN
- verify the switch has Active Group Addresses
- Enjoy !!!
Thanks again at all the FOG team