Question

I would like to ping many different hosts simultaniously. Does .NET handle this concurrency for me, or must I implement this myself?

For example, the following object internally uses the Async version of ping:

Mypinger.Tracert("microsoft.com");

And I may have a different instance doing the same thing, but to a different host at the same time:

Mypinger.Tracert("google.com");

What prevents the concurrent Async methods from each instance interfering with each other?

What is the limit on the concurrency?

Answer 1

Yes. Use the Async variants of the various methods on the Ping class.

Adapted from the examples in the Ping class documentation:

private void SendPing()
{
    // ...
    Ping pingSender = new Ping();
    pingSender.PingCompleted +=
             new PingCompletedEventHandler(PingCompletedCallback);

    // the async methods don't block,
    // and execution will continue after the following call
    pingSender.SendAsync(address, userToken);
    // ...
}

private void PingCompletedCallback(object sender, PingCompletedEventArgs e)
{
    // ...
    PingReply reply = e.Reply;
    object userToken = e.UserState;
    // ...
}

With regards to your edit and comment, although ICMP communication is typically stateless, ECHO messages (used in pings) maintain connection state, and so know what ping requests triggered a given response. There’s really no limit on concurrency, excluding connection swamping.