On Friday 25 April 2003 02:50, Saikrishna Dasari wrote: It looks as if for some reason, the communication between sender and receiver has been cut completely. Maybe some switch getting confused with the udpcast's multicast packets? We had once a case where a 3com switch would block all traffic for 30 seconds, then open up again, and let them pass for another 30 seconds..., and then close again. So every 30 seconds, we would get a flurry of such messages. UDPcast did cope, although the transfer did obviously twice as long as it otherwise would have... Could you check whether devices of two different speeds are connected to the switch (such as 100 Mbps computers, and maybe a 10 Mbps printer?). Try disconnecting all 10 Mbps devices, and check whether the problem still occurs. Udpcast does produce a safe transfer: if packets are dropped, they are retransmitted. However, if the retransmissions also fail, udpcast will eventually consider that receiver as dead, and "drop it" from the list of receivers in order to be able to continue with those receivers that do not suffer from the problem. Alain