Alain Knaff wrote:
What exactly is "new"? New make of network card? New switch? More than one switch between sender and receiver? Maybe even a router? Is it possibly for you to test each change "one-by-one", to try to identify which particular change brings the problem.
A extra networkcard in the server and 1 switch connected to it (for testing) with 4 machines connected to it (for testing). There are no routers between them.
It looks like the "return" traffic (from the receiver back to the sender) is not working correctly. It's somewhat bizarre, because apparently it did work at the beginning of the transfer (or else the transfer could not have taken place at all, unless you used asynchronous mode)
Indeed weird, only at the end the problem seems to arise. I am not running in asyncrhonous mode.
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From the IP addresses, I assume you are using unicast mode (one single receiver).
It would help if you would tell us more about your network. What devices (switches, routers, etc.) are sitting between your sender and your receiver? What netmasks are involved? Where was the tcpdump observed (on sender? on receiver? on an unrelated box? If so, how was that box connected?) Are you reasonably sure that the trace is complete? (Many switches send unicast traffic only to the port where that machine is connected, unless you use a specifically configured monitoring port. That means that if you used an unrelated box to observe, the trace might be incomplete, depending on how the switch(es) has(ve) been set up)
Alain
Yes, I tried this particular case in unicast mode, to eliminate any possible multicast issues that might arise. I would figure a unicast setup should work, even if the switch has problems with multicasting. The network on networkcard X is a /22 network (255.255.252.0), the network on networkcard Y is a /21 network (255.255.248.0). The tcpdump was done on the sending side/image server, so I should be able to see the return packets in the tcpdump (I see return packets during transferring earlier on). The setup pretty much looks like this right now: server networkcard Y ->| switch |-> machine 1 |-> machine 2 |-> machine 3 |-> machine 4 Kind regards, - Ramon. -- There are really only three types of people: Those who make things happen, those who watch things happen, and those who say, "What happened?" --- ing. R. Bastiaans HPC - Systems Programmer SARA - Computing and Networking Services Kruislaan 415 PO Box 194613 1098 SJ Amsterdam 1090 GP Amsterdam