Sockets Command-response Timeout?

provide an example of a client server app using the System.Net.Sockets class that:

(a) supports multiple client connections

(b) that implements some sort of command-response timeout feature (by that I mean, once a client connects the server sends the client a message [e.g. Message A] and waits without blocking communication with other clients for a response. If a response is not received within a defined period it tries again perhaps and if there is still no response then it disconnects the client. If a response is received then it sends another message [e.g. Message B] and so on....Whilst this is going on the server must be able to accept connections from other clients).

If anybody has done something like this before and is willing to share their knowledge I'd be grateful. I've been trying for ages to get the timeout feature working correctly to no avail. I haven't posted what I have already because frankly it's a mess. I tried an ArrayList of timers (one for each client) that I started and stopped as messages were sent and received, but the timer elapsed event kept firing after I thought it should have stopped which may have something to do with the various threads involved with the asychronous communication I was trying to use (I really dont know).

It's really the server end that I'm having problems with because the client app only has to deal with messages coming from a single source. At this stage I don't care if it's done using synchronous or asychronous communication. I've trawled the web for every example I can find and but I can't find one that implements this kind of command-response timeout with multiple clients - i.e. most of them just show how to listen out (server) and connect (client) and how to send a message, i.e. there's no sequence of messages or timeouts.