I am using Boost's ASIO libraries to establish a UDP connection to a remote server. To make sure the connection is active, every second a keep-alive message is sent to the server.
I have noticed that if I unplug the network cable and reinsert it quickly, the first 2 or 3 keep-alive messages after the reinsert are never sent. I tested this by running wire-shark on the server. I have seen it take up to 5 seconds before the client starts sending out network traffic again.
The client is running under Linux (2.6.2), if that helps.