I'm sorry for ignoring the node for so long. I took some days off from work for an exam -.- I've read the whole discussion and I'd like to thank you for your replies.

As above mentioned the UDP packet size is never bigger than 65535 bytes, and the read won't last 10 secs either.

While sending out the hexdump the server will notice the heartbeat and will send a response after it sent the data. The server will always respond to the heartbeat. Also we know for sure, that there is no hexdump which contains only one byte. They have several types and the smallest is around 20 bytes.

The server can do with some delay in receiving the heartbeat. For testing it's fine to set up the timer to send heartbeat in every 9.9 secs.

"The sending of the hexdumps is initiated by the server, when they become available; provided that is within 10 seconds of a heartbeat." It's possible that we start the server and there is no hexdump ready. So it is possible that we have to wait for several minutes for the first hexdump to come. The client continues to send the heartbeats regardless of it receives no data.

I hope I've answered everything that wasn't clear.